Individual interactions within social groups underpin social structure, though it is not always clear which aspects of these structures are meaningful to the individuals embedded within them. We propose a temporal framework that considers explicitly how–and to what extent–past social structures influence future behaviour. We propose that the magnitude of behavioural sensitivity to different measures of social structure can indicate the relative importance of these measures to individual group members, an idea we refer to as the social sensitivity hypothesis. We use grooming and aggression data from a population of wild vervet monkeys to test predictions derived from this hypothesis. Specifically, we estimate the influence of one global, two triadic (local), and three dyadic network measures on subsequent grooming behaviour. We also test whether the extent of sensitivity is contextual by estimating how it responds to food availability. We show that individuals were most sensitive to past dyadic interactions, particularly prior grooming given and received. Triadic effects, such as sensitivity to grooming partner’s grooming choices, were strongest in contexts with high food availability. In contrast, the impact of aggression was reversed across high and low food contexts. At the global network level, individuals were influenced by past community membership, even after accounting for dyadic and triadic social structures. These findings illustrate how a social sensitivity approach can uncover not just what aspects of social structure matter, but when and in what contexts. By taking a dynamic view of social networks and identifying the structural dimensions individuals are most sensitive to, we can better understand the perceptual and cognitive processes that guide social behaviour, and how these, in turn, influence fitness-relevant outcomes.

Weaver ants, Oecophylla smaragdina, can live in large colonies, are very aggressive, and defend their nesting trees as territories against other colonies. Since territorial fights can be costly, these ants have been hypothesized to use their excrement as territorial markings serving as cues or signals to their own and competing colonies. However, little is known about the spatial patterns of potential mark deposition, how ants decide when and where to defecate, and how ants react to these spots. We let colonies of weaver ants explore an empty arena in the lab and recorded ant positions and mark depositions every 10 seconds over 9 hours, and in 24 frames for 2 hours. We find that 1) ant numbers peak after about 2 hours after which they slowly decline to a stable level, possibly due to an active colony-level exploration behavior, 2) mark deposition slows down after an initial phase after which the rate stays constant, which means that ants do not reduce their marking activity on highly marked areas, 3) marks tend to be laid less in areas with high ant density, indicating that ants favor marking less occupied regions, though they do not strictly avoid laying marks on top of preexisting marks, 4) ants lay marks relatively early in their exploration bout. These results suggest that ants have a strong drive to mark novel areas but do not finely regulate the position and density of marks.

Play in animals can have diverse functions from acquiring information about the environment to development of various behavioural and cognitive skills. For instance, social play may facilitate the development of social relationships, while object play may enable environmental exploration or the development of foraging skills. However, not much is known about how individuals may use objects to initiate social interactions with others. Captive ravens are known to engage in a variety of play behaviours, including social object play. Here I present two studies on object play in a group of individually marked free-flying ravens that has been monitored over 15 years. In the first study, we analysed 3257 focal observations on 163 marked individuals, collected over 9 years. We report the occurrence of object-handling behaviour in adult ravens under free-flying conditions and validate findings from captivity concerning the patterns of object play across age and season. These results suggest that object play has more than one function and serves to gain information about the individual’s physical and social environment. In the second study, we test the hypothesis that ravens may engage in object play to attract the attention of and initiate interactions with other ravens. Analysing 493 play bouts from 51 marked individuals recorded between October 2021 – December 2023, we find support for our hypothesis. These findings suggest that birds with complex social life show primate-like play patterns that shape their social relationships.

Having young that require high levels of parental care is a risky strategy for solitary breeders, as all fitness is lost if the breeder dies before their offspring reach independence. Hence, cooperative breeding and sociality may be favoured by selection in such cases, according to the theory of Assured Fitness Returns (AFR). This is because a breeder that dies during the parental care phase can gain fitness via AFR if the remaining allo-parents in the social group continue rearing their orphaned young.

Here, we propose that AFR may select for group living even in the absence of direct cooperation among adult group members, if neighbours are willing to adopt orphaned young. We test this hypothesis in two closely related communal Chikunia spiders that live in mixed-species colonies. Neither species shows direct cooperation with group members and instead aggressively maintain individual territories.

We ask: 1) Do females adopt, and care for, intra- and inter-specific orphans, thereby providing AFR to deceased mothers? 2) Are females more likely to adopt related young? 3) Are neighbours closely related, allowing for mothers to gain indirect fitness benefits from rearing orphaned young? Our results indicate that AFR via intra-, but not inter-specific, brood adoption may select for communal living in both species, supporting an expansion of the theory of AFR to include selection for non-cooperative group living as well.

Short-term weather events that modify resource distribution can influence animals’ decisions to join or leave a group. While connections to conspecifics may usually provide benefits, such as increased information transfer, they can become irrelevant or even costly when competition increases. Flexibility in social behaviour enables animals to cope with variation in social costs and benefits resulting from changing ecological conditions. We investigated this social flexibility in snowfinches (Montifringilla nivalis), a bird species adapted to alpine habitats where weather can change rapidly. In winter, snowfall and temperature strongly affect food availability and foraging needs. We observed colour-ringed snowfinches at two study sites in the Swiss Alps to understand how individuals adjust their sociality to weather changes and how weather conditions shape their group structures. We assessed social associations by recording which individuals foraged together in groups. We estimated dyadic association probabilities using a model, that accounts for imperfect detection of individuals. Preliminary results suggest that snowfinches exhibit uniformly weak associations under harsher conditions, whereas milder conditions reveal a mix of strong and weak ties, indicating more pronounced social preferences. These findings suggest that in adaptation to alpine environments, social behaviour in snowfinches is context-dependent and variable.

Animal behavior is closely linked to weather conditions, influencing individual fitness, species distributions, and the survival of populations facing climate change. Urban environments, where weather events are often intensified, can pose additional challenges to wildlife. To understand how urban butterflies respond behaviorally to changing weather and weather extremes, we monitored five common species in Bengaluru, India, over the course of a year. In total, 1,011 individuals were observed, and their time spent flying, feeding, resting, and basking was recorded under natural weather conditions. Each of the four activities were analyzed separately using a Generalized Linear Model (GLM) with binomial errors with the proportion of an observation showing that activity as the response variable, and with temperature, rainfall, windspeed, temperature anomaly and slope of the temperature trend over a three-day window as predictors. Across species, feeding activity generally declined as temperature increased, while flight activity increased. Periods following heavy rainfall were associated with greater feeding activity. However, neither temperature anomalies nor extreme conditions such as heat waves or cold spells showed consistent effects, suggesting that these tropical butterflies adjust primarily to short-term weather variation rather than longer-term climatic deviations. Species-specific differences were also apparent: feeding decreased with rising temperature in the Common Four-ring (Ypthima huebneri), Chocolate Pansy (Junonia iphita), Lemon Pansy (Junonia lemonias), and Tawny Coster (Acraea terpsichore), but increased in the Common Grass Yellow (Eurema hecabe). Our findings underscore the role of behavioral flexibility in enabling butterfly species to persist in urban settings under changing climatic conditions. Recognizing such behavioral adaptations is essential for forecasting local distribution shifts and for guiding conservation planning in cities.

Increasing human presence and activities expose wild animals to persistent disturbances. Disturbed populations often become tolerant towards humans, although the underlying mechanisms are poorly understood. We used playback experiments to manipulate perceived level of human disturbance in great tits (Parus major). In the first year, incubating females remained more often on the nest, and parents during brood care exhibited a lower level of vigilance and tended to have shorter return latencies in the human disturbance treatment than in control treatments, demonstrating an increased tolerance. These differences disappeared in the second year. Tolerance was also influenced by distance to roads and the frequency of nest visits by researchers. These results support that behavioural tolerance can quickly emerge by phenotypic plasticity in natural populations, although other mechanisms may also influence behavioural responses after longer exposure to human disturbances resulting in a complex set of processes involved in the spread of tolerance.

The alarming growth of the human population and its development worldwide represent a formidable challenge for wildlife. Urbanised areas featured a range of novel stressors such as habitat alteration, introduced predators, new food sources and human disturbance. Insular species are among the most vulnerable, as their adaptations associated with the ‘Island syndrome’ might represent a disadvantage in facing the drastic changes introduced by urbanisation. Therefore, species will need to adjust aspects of their behaviour to cope with these novel stressors and survive. Of particular interest are the Galápagos Islands, which have been facing significant anthropogenic impacts for the last 30 years due to increased tourism. Our study aims to estimate the impact of urbanisation and wildlife tourism on the behaviour of Galápagos lava lizards, focusing on islands that represent a gradient of urbanisation from highly urbanised to isolated. We hypothesised that Galápagos lava lizards exposed to high levels of urbanisation would show human-induced behavioural adjustments, such as increased scanning activity. Our results suggest that species occurring on highly urbanised islands spent more time active than those on less urbanised islands. At the same time, lizards also showed overall lower levels of vigilance in urban areas. Interestingly, within-species comparisons on Santa Cruz Island elucidated a higher vigilance in highly touristic sites; yet vigilance behaviour was generally still lower than on other islands and probably reflected a positive relationship with population abundance. Social interactions seem to be unaffected by the urbanisation level. Our study demonstrates the influence of urbanisation and tourism on a non-emblematic species of the Galápagos Islands, yet one that is extremely important in the natural ecosystem. We have provided a basis for future and more comprehensive conservation programs since the early 2000s.

While animals rely on behaviour to cope with challenges, the disruption of behavioural processes by stressors can cause cascading consequences at individual and population level. Pollinators and bees provide powerful models to investigate these dynamics, as their behaviour underpins fitness and organization at individual and social level while guaranteeing wide contributions to our society. Here, we illustrate both the power and complexity of using behaviour to assess impacts and emphasise an emerging goal of our research: integrating behavioural knowledge into societal decision-making.

First, we synthetize the limited knowledge on sublethal effects caused to pollinators through a meta-analysis approach: most research focuses on honey bees (78 %) and 71% of the most used pesticides have no reliable sublethal effects data (poorer data for other stressors). We further investigated a range of behavioural paradigms to provide sensitive and ecologically relevant information on pollinator’s health, towards potential adoption in official decision-making processes, like risk assessments. Investigating courtship and reproduction, we demonstrate that a common pesticide (sulfoxaflor) reduces pre-copulatory display (-36%) and sounds (-27%), increases mating duration (+166 %), and finally reduces sperm quantity (-25%) and mating success (43%) in wild bees. Developing ethograms, we aim at quantifying stress-induced behavioural impairment across pollinator species via scalable, reproducible techniques. Investigating bee cognition (i.e., decision-making) and communication, we highlight pathways through which sublethal effects translate into population-level risk, proposing emerging behavioural paradigms that can detect disruptions in social regulations.

By presenting these both preliminary and published lines of evidence, we discuss the position of behaviour as both a primary target of stressors and a critical bridge between experimental research and societal application.

12 12. Chemical communication

Cleaning symbioses typically involve cleaners removing ectoparasites from a larger client species. In marine systems, the stability of cleaning behaviour varies according to the risks, including parasitism and opportunity costs. However, little is known about how fluctuating resources influence the stability of cleaning relationships. Here we studied this question using the rare mammal-mammal cleaning relationship between banded mongooses and warthogs, at our long-term study site in Uganda. In this population, warthogs solicit banded mongooses to remove ticks and other ectoparasites. We analysed cleaning engagement and duration over three years to test whether cleaning interactions were shorter, or less frequent, during periods of high rainfall, when mongoose invertebrate prey are relatively abundant. We also experimentally fed mongooses to test for short term impacts of supplementary feeding on the frequency and duration of cleaning behaviour. Preliminary results show no significant effects of either long- or short-term variation in food availability. However, there was considerable unexplained within-group variation in the propensity of individuals to engage in cleaning. The findings suggest that the mongoose-warthog cleaning relationship is robust to seasonal and short-term variation in food availability. We suggest that cleaning behaviour depends at least in part on levels of intragroup competition in banded mongooses.

Individuals use a subset of the population’s resource base, a phenomenon called individual specialisation. It reveals the presence of among-individual niche variation often explained by sex, age or morphotypes. Among-individual differences in behaviour are related to resource acquisition and/or use, but whether they also mediate individual niche specialisation remains unclear. This integration of personality traits as niche mediators most likely dependents on ecological contexts. Yet, few studies have studied niche specialisation in the context of disturbed environments such as urban habitats. Here, we aim to test whether individuals exhibit behavioural differences leading to individual niche specialisation under urbanisation. We focused on three behaviours (boldness, exploration, docility) and two niche dimensions (microhabitat use via ground vegetation height and diet via δ15N and δ13C isotopic ratio from hair and nail) of two small rodent species, Apodemus sylvaticus (N=190) and A. flavicollis (N=63). All behavioural traits and niche dimensions were repeatable over time. Bolder individuals predominantly used areas with low ground vegetation in non-urban, but not urban, habitats. Bolder individuals fed more on higher trophic level food (i.e. higher δ15N in hair) in non-urban, but not urban, habitats. Our results suggest that personality traits mediate microhabitat and dietary niches, but these effects break down under urbanisation. Urbanisation can alter predator-prey dynamics by reducing predation pressure and diminishing the ecological relevance of traits such as boldness. Our study highlights how individual differences in behaviour are linked to specific food usage and spatial distribution of phenotypes in an ecosystem. The individualised niche framework opens new avenues for understanding how individuals actively change their use of the environment via their intrinsic characteristics, with potentially profound effects on community dynamics and structures.

While numerous studies have documented consistent-individual-differences (CIDs) in boldness-fearfulness relative to predation risk, much less is known about CIDs in fear of other important threats (e.g., pathogens, moving vehicles, pesticides). Although fire is an established and/or growing threat in many places, surprisingly few studies have examined behavioral responses to fire, and even fewer have looked at CIDs in response to fire cues such as smoke, or fire residues such as ash. We addressed this gap by quantifying how animals respond to smoke or ash, and CIDs in these responses in a range of organisms – wolf spiders, terrestrial pillbugs, Hawaiian day geckos and freshwater snails. Most interestingly, we tested for fear generalization (Sih et al. 2023 TREE) – here, the idea that CIDs in fear of smoke or ash might be correlated to CIDs in fear of predators. Our studies are among the first to examine fear generalization in non-humans. Our results quantified a diverse array of behavioral responses to smoke or ash, and revealed evidence in multiple species for both CIDs in response to smoke or ash, and for fear generalization. We briefly discuss factors that might explain or mediate the positive correlation between fear of predators and fear of smoke or ash, and potentially important ecological and evolutionary implications.

Animals exhibit consistent individual differences in behavior, and this variation can shape important ecological interactions, including mutualisms. Marine cleaning mutualisms involve shrimp that remove parasites from larger client fish. In the cleaner shrimp Ancylomenes pedersoni, small groups occupy cleaning stations and interact with a wide diversity of reef fish species. Previously, we have shown that individual cleaners differ in behaviors such as activity level and risk response, which may influence their willingness to interact with certain clients and the quality of service they provide. However, behavioral variation in cleaner shrimp has so far been demonstrated primarily under laboratory conditions and has largely focused on single trait-outcome relationships. Here, we examine how variation across multiple behavioral traits at the individual level influences interaction outcomes at cleaning stations in the wild. Specifically, we tested whether differences in individual cleaner behavior are associated with interaction frequency and the diversity of client species served. To do so, we individually marked 45 cleaners across 27 cleaning stations in Curaçao and recorded video footage of cleaner–client interactions. Cleaners were then collected and subjected to behavioral assays quantifying boldness, activity, and neophobia behavior. Using a behavioral hypervolume framework, we then quantified multidimensional behavioral variation at the individual level and related it to the abundance and diversity of visiting clients. By linking individual behavioral variation to ecological outcomes in the field, this work provides insight into how cleaning mutualisms are structured and maintained, with implications for reef community health.

Movement and information use strategies are identified as key factors influencing the ability of animals to adapt to human-induced global changes. These strategies are found to correlate with personality traits measured under standardized laboratory environments. Here we examine how personality differences might underlie differences between individuals in coping with ongoing rapid environmental changes in Great Knots (Calidris tenuirostris), an endangered long-distance migratory shorebird threatened by loss and degradation of their main coastal refuelling sites halfway between their Northwest Australian nonbreeding area and their eastern Russian mountain tundra breeding grounds. Although the number of sites visited during migration did not correlate with individual exploratory tendencies, birds that were more explorative visited proportionally more new sites during southward migration. At a main staging site where the prey stock of the birds had collapsed, explorative individuals moved on to other staging sites sooner. Explorative individuals, compared with non-explorative individuals, arrived earlier on breeding sites and tended to stay longer there, the latter suggesting successful reproduction. We propose that explorative individuals are better at acquiring environmental information, enabling them to respond faster to environmental changes e.g. sudden food declines. Moving to alternative sites enables them to fuel up faster, and thus arrive earlier on breeding sites which, in turn, helps them to breed successfully. Accordingly, variation in exploratory tendencies within a population could be key to adaptive capacity to rapid human-induced environmental changes in long-distance migratory shorebirds.

Correlations among personality traits, defined as behavioral syndromes, can be shaped both by constraints and correlational selection. In a constraint scenario, potentially driven by gene pleiotropy or mechanistic determinants, the evolution of one behavior will drive changes in correlated behaviors, potentially leading to maladaptive conditions. In an adaptive scenario, syndromes have the potential to be shaped by local selection pressures. When multiple personality traits are considered at once, the two mechanisms could interact, producing hybrid patterns of trait association. We used multivariate Bayesian regression models on six movement behaviors in 23 populations of long term monitored GPS-tagged red deer (Cervus elaphus), distributed across Europe, within the Euromammals project. Behaviors showed high repeatability, and subspace comparisons of the resulting covariation matrices revealed a strongly conserved covariation axis across populations, composed by average speed, occupied space, and intensity of area use. This axis likely indicates a mechanistic constraint emerging from speed requirements in space use change, which persists across populations despite divergent environments. The other three behaviors (diurnality, residence time and time to return to residence) showed high inter-population variability in intensity and direction of their covariation. Through a tensor analysis, we further aimed to investigate whether the variable parts of the movement syndromes were systematically influenced by environmental differences among populations, unveiling a complex scenario in which syndromes’ structure can change across environments while the constrained speed and space use axis anchors the system, compelling other behaviors to adjust around it. These results show how movement syndromes can change their structure in response to the changing environment, but constraints have the potential to influence this response.

Alarm calls are widely used to reliably inform conspecifics about the presence of danger in social species. In some cases, alarm calls also encode information about the category of the threat or the perceived risk. Functional reference describes when an alarm call is specific to a predator label, whether a terrestrial or aerial attack for example, and prompts an appropriate escape response in the receiver of the call. Urgency based systems allow for changes in call parameters, such as rate, to indicate the level of threat by communicating information like distance or size. Long-tailed tits (Aegithalos caudatus) use two different types of call in response to potential threats: the ‘m’ call and the ‘churr’ call. The aim of this study was to test experimentally whether the use of these calls supported either a functionally referential or an urgency based system. We presented breeding pairs with four different types of perched taxidermy models representing different levels of threat and, subsequently, conducted a playback experiment where we manipulated both the urgency of calling and the call type (m or churr). In both experiments we measured parameters reflecting call structure and use, and recorded focal birds’ behavioural responses. During model presentations we found that long-tailed tits had a graded response, increasing their rate of churr calling as the threat posed by the model increased. The m alarm call was very rarely uttered in response to perched models, however, it is produced in response to predators flying overhead. This was reflected in responses to playbacks, where long-tailed tits exhibited classic ‘escape’ behaviours to the m call, yet adopted ‘investigative’ behaviour towards churrs. Collectively, our results indicate that long-tailed tits use a combination of both urgency and referential alarm calling systems, their use depending on the level of threat and its context.

Many social animals live in complex multi-level societies in which there is a hierarchy of organisational units. The costs and benefits derived from interactions between individuals in such systems may depend on their respective levels within that society. Therefore, if the capacity of an actor to recognise the position of social partners within a hierarchy has significant fitness consequences, selection for a recognition mechanism that allows discrimination of different social levels is expected. Here, we take a hierarchical mapping approach to investigate variation in vocal recognition cues across the multi-level society of long-tailed tits Aegithalos caudatus, a cooperative breeder in which helpers exhibit a kin preference in their helping behaviour, and in which inbreeding with close relatives is avoided. We employ a machine learning approach, using a convolutional neural network model to analyse variation in vocal signals across the social hierarchy: individuals, nuclear families, extended families, social groups (composed of kin and non-kin) and residence status (resident or immigrant). We show that long-tailed tit vocal signals encode reliable information about individual and nuclear family status, but that social information content at higher levels in the hierarchy is relatively weak. We relate the outcome of this hierarchical mapping procedure to the behavioural decisions of long-tailed tits in the context of helping and mate choice. We conclude that a knowledge of recognition mechanisms and the resulting ability of individuals to discriminate between categories of social partners is critical for understanding adaptive decision-making in social animals.

In over a thousand avian species, pairs coordinate various vocalizations or sonations to duet. Songbirds may use calls (simple, unlearned vocalizations) and songs (complex and learned vocalizations) to form duets with their partners. We recently described female response-driven song duets in the Galápagos Yellow Warbler (Setophaga petechia aureola) in which females also use their “chip” calls in response to the male song to form another type of duet. While the sister species, Northern Yellow Warbler (S. aestiva), also produces these “chip” call duets, they don’t have song duets. This raises the question: why did the song duets evolve in the Galápagos Yellow Warblers? We observed 10 pairs for 17 hours and recorded 1515 instances of duetting or duet initiation attempts. For each of these vocal events, we narrated the context of the focal pair’s behavior to understand sex roles, the function of duetting, and duet types. More specifically, we investigated associations between duetting and three different contexts: 1) proximity to partner, 2) agonistic encounters, and 3) counter-singing. We found that the majority of the song duets and almost all of the call duets were initiated by males, and duet initiation was more likely to be answered by females. The probability of answering the partner depended on the sex and the context. Females were more likely to answer their partner when they were closeby and counter-singing. No such relationship was present for the male answering. Agonistic encounters were not associated with answering in either sex. Moreover, for the male-initiated duets, the probability of answering with a song rather than a call was higher when the pair was closer to each other. These suggest females may answer their partners to signal territory ownership and association with their partner, and song duets may have evolved for the latter. Moreover, our results emphasize the importance of considering individual roles while evaluating duet functions.

14 14. Animal personality

Passive acoustic monitoring (PAM) is widely used in wildlife research as a non-invasive tool to investigate the presence, abundance, distribution, and behaviour of vocal species across broad temporal and spatial scales. However, the large volume of collected data poses substantial computational challenges, often limiting data processing and analysis. Lemurs, one third of whose species are classified as Critically Endangered by the IUCN, require accurate and timely monitoring of wild populations. Many species inhabit remote forest remnants and exhibit conspicuous vocal behaviour, making them ideal candidates for PAM-based studies.

Here, we investigated the vocal activity of indris (Indri indri) and black-and-white ruffed lemurs (Varecia variegata) using passive acoustic recordings collected in Maromizaha Forest between 2019 and 2023. We first developed a convolutional neural network (CNN) to detect the presence or absence of indris’ songs, loud vocal sequences, across 66,443 ten-minute recordings. The model achieved high performance (accuracy >90%, recall >80%), demonstrating the feasibility of automated song detection through a tailored workflow. Building on this, we applied BirdNET, a CNN originally designed for bird vocalizations, to the automatic detection of loud calls of both lemur species. After manual optimization of model parameters, the selected model reached precision and recall values of approximately 90% for each species and was applied to 55,515 recordings. Finally, we conducted temporal analyses to describe diel and seasonal patterns of vocal activity. Our results show that tools such as BirdNET can be successfully adapted to non-avian taxa, enabling efficient acoustic analyses even with limited computational expertise. Moreover, this study highlights the value of PAM for advancing our understanding of the vocal behaviour of threatened species, with important implications for species detection, monitoring, and conservation planning.

(1) PhD Student, Indian Institute of Science Education and Research, Tirupati, Tirupati, India - (2) Associate Professor, Indian Institute of Science Education and Research, Tirupati, Tirupati, India

Acoustic communication systems are shaped by both signal production and reception. Acoustic character displacement (ACD) describes the divergence of signal structures in closely related sympatric species. Overlap in acoustic space often leads to interference, favouring the evolution of distinct vocal traits. Consequently, receiver recognition of such divergence can predict signal specificity in sympatry.

We investigated ACD and receiver responses in palm squirrels (Funambulus spp.) across two regions of the Western Ghats, India, which are distinguished by their species composition and acoustic overlap. In the Southern Western Ghats (SWG), F. palmarum and F. tristriatus co-occur with overlapping acoustic niches. Whereas, in the Northern Western Ghats (NWG), F. pennantii, vocalising in higher frequencies, co-occurs with F. tristriatus, resulting in lower acoustic overlap. Comparative analyses revealed that call types across various behavioural contexts diverged between sympatric and allopatric populations, consistent with ACD.

To test the biological relevance of this divergence, we conducted playback experiments in which focal individuals were presented with contact calls of sympatric, allopatric and neutral controls. We quantified response latency, response score, and behavioural propensity. Across both regions, squirrels responded most quickly and strongly to sympatric calls followed by allopatric and least to neutral ones. Notably, F. tristriatus exhibited stronger responses in the SWG than in the NWG, suggesting heightened receiver sensitivity in contexts of greater acoustic similarity.

These results demonstrate that acoustic character displacement in Funambulus squirrels involves not merely signal divergence but also context-dependent receiver recognition, indicating strong signal specificity. By integrating signal evolution with behavioural responses, this study highlights how communication systems facilitate species coexistence in complex acoustic communities.

Social species can adapt to changing environments by modulating social behaviour. Modified individual behaviours may translate into group-level effects, such as altered group size and composition. Such a flexible social response can act intragenerationally, enhancing social benefits that may improve fitness under adverse conditions. This flexibility can help species persist in challenging environments. Although the fitness benefits and mechanisms of social plasticity have been studied previously, further research across species with varying mating systems and life histories is needed to fully understand how species-specific traits affect this capacity. We investigated the adaptive nature of intragenerational social plasticity in Cape ground squirrels (Xerus inauris), a longer-lived, arid-adapted, communal breeder. By analyzing 18 years of data on climate, reproduction, survival, group size, and composition, we found that group sizes increased during cold years, driven primarily by higher numbers of adult females per group. Conversely, warm years were associated with an increase in adult males that delayed dispersal and remained in their natal family group. These compositional alterations facilitated group-level benefits during extreme thermal conditions, such as bolstered survival during cold years and improved reproductive output during warm years. Our results demonstrate climate-driven social plasticity in this species, mediated by altered dispersal decisions that ultimately support survival and fecundity under challenging thermal conditions. These findings showcase the potential of intragenerational social plasticity as a rapid response mechanism to climatic variability. As climate change intensifies, it will be crucial that we understand these adaptive behaviours so that we can predict species resilience and guide future conservation efforts.

Climate change is increasing the frequency of hot temperatures and drought, exposing animals to harsher conditions. Altricial young rely on parents to provide them with the additional resources required to match their higher energetic demands under adverse climatic conditions, yet at the same time, costs of providing parental care increase under such conditions, limiting parents’ ability or willingness to do so. In cooperative breeders, the provision of alloparental care by helpers has been proposed to buffer against adverse conditions, mitigating climate change impacts on reproductive success. Here, we test this by investigating how climatic conditions affect offspring provisioning in the endangered purple-crowned fairy-wren (Malurus coronatus). This species is endemic to monsoonal northern Australia, an area characterised by high temperatures and highly variable rainfall within and between years. Nestlings in this species are affected by heat (they have lower condition) and hot, dry conditions (they have shorter telomeres), both of which reduce survival. We show that total nestling provisioning rates are greater in larger groups. In dry conditions, provisioning is enhanced in larger groups, because helpers provide a greater relative contribution of care when conditions are dry. However, when dry conditions coincide with hot temperatures, nestling provisioning effort is no longer increased. Hence in this tropical fairy-wren, the presence of helpers seems to buffer against drought but not heat, since when dry conditions coincide with heat, and (allo)parental care is presumably most costly, adults no longer maintain provisioning effort.

Social complexity during development is predicted to shape behavioural phenotypes in social animals, yet experimental tests isolating ontogenetic effects remain rare. Cleaner fish provide a powerful model to address this question, as their cooperative behaviour and social cognition are well characterised in the wild and laboratory. Here, we experimentally tested how early-life social complexity influences cooperation and cognition in cleaner wrasses Labroides dimidiatus. Juvenile cleaners were raised for five months in mesocosms under two contrasting social environments: low client complexity (three client species with one individual each), and high client complexity (three client species but two with five individuals and one with two individuals). Following the rearing period, cleaners were subjected to a set of behavioural tests assessing both social and asocial cognition. Social cognition tests included feeding against preference (cooperativeness), biological markets, and audience effects. Asocial cognition was assessed using a spatial discrimination task (plus maze) and a detour test. Cleaners raised under high social complexity exhibited significantly higher cooperativeness, feeding against their preference more frequently than individuals raised under low complexity. In contrast, no differences were detected between treatments in audience effects, biological market performance, reversal learning, or asocial cognitive tasks, including spatial discrimination and detour performance. These results suggest that early social complexity selectively enhances cooperative tendencies without broadly altering cognitive performance. Our findings support the idea that social experience during development fine-tunes specific components of social behaviour rather than inducing generalised cognitive changes. This highlights the importance of ontogeny in shaping cooperative strategies and provides evidence for experience-dependent plasticity in social behaviour.

In animal societies, an individual’s social relationships can have profound implications for their realized fitness. In baboons, high social status and close affiliative relationships are thought to offer fertility and/or survival benefits to adult females, potentially by affecting their ability to compete for resources. High ranking females may win conflicts over resources more often than low ranking females while socially connected females may be better tolerated by conspecifics while foraging and learn how to access valuable resources more frequently than less connected females. To test this hypothesis, we drew on data from an eight-month study of 42 female baboons in the Amboseli basin of Kenya to determine whether female rank or sociality predict three outcomes related to feeding competition: i) the number of bites obtained per unit of foraging effort, ii) diet composition, and iii) and the rate of agonistic interactions. Preliminary results suggest that females who are higher ranking and more socially connected feed more frequently on certain high quality foods (e.g., seeds and gum) and receive less directed aggression, including while feeding. These observations suggest that differences in social capital lead to detectable differences in foraging-related outcomes, although notably the relationship between social connectedness and diet composition could be explained by reverse causality if better diets free females to invest more time in affiliative social interactions. Rank and social connection-related dietary differences are only detectable in high rainfall conditions, however, suggesting that social gradients are environmentally context-dependent in female baboons, at least with respect to feeding competition. We thus discuss the implications of intensifying drought for social evolution.

Intrasexual competition is a widespread and pervasive evolutionary selection pressure, especially among group-living species, as individuals compete with conspecifics for limited resources to maximise their survival and reproductive success. Although winning contests often yields clear benefits, such as access to mates or nesting sites, aggressive actions also impose costs, many of which are harder to quantify, including non-lethal injuries and energetic expenditure. Disentangling the fitness consequences of aggression therefore remains challenging, and most studies rely on linking correlations between aggression and fitness outcomes. In particular, the fitness effects of aggression in females are poorly understood. Female competition has historically been overlooked, in part because females typically compete over reproductive or ecological resources and display less intense aggression.

To directly test the effects of aggression on female fitness, we experimentally manipulated female aggression in Drosophila melanogaster. We blocked synaptic transmission of neurons involved in regulating female aggression, thereby reducing female aggression. Using mated females, we quantified their reproductive success under differing levels of competition relative to genetic controls. Similarly, we assayed lifespan under starvation conditions in both manipulated and control unmated females to capture the metabolic costs of aggression.

Our results detect a fitness cost of aggression: females with increased aggression show reduced stress resistance under high competition conditions. However, we found no evidence that more aggressive females benefit through increased reproductive success. The absence of a detectable fitness benefit suggests that female aggression in Drosophila melanogaster may be shaped by intralocus sexual conflict, or alternatively, that the potential advantages may only emerge when measuring female lifetime reproductive success or grand-offspring production.

Parental cooperation is not self-evident, as conflicts often arise over individual contributions. Evolutionary game theory suggests this conflict may be resolved through negotiation, where parents adjust their care level based on their partner’s contribution. However, mathematical negotiation models typically predict low parental cooperation. As these models are not dynamically explicit and mostly neglect stochasticity, we employ individual-based simulations to investigate how parental negotiation strategies evolve and shape care patterns. Our results differ markedly from earlier analytical predictions. Parental negotiation strategies readily evolve, producing four alternative care patterns: uniparental care, sex-biased care and two types of egalitarian biparental care, that occasionally emerge as transitional stages over evolutionary time. Effective cooperation evolved regularly but, contrary to common expectations, always relied on a Tit-for-Tat strategy rather than parental compensation. Our study underscores that diverse cooperative patterns in animals can emerge from sex-specific negotiation strategies, even in the absence of initial sex roles and environmental variation.

Parental care strategies may vary across populations in response to local ecological conditions, yet how such variation influences reproductive outcomes remains poorly understood. In the tawny owl (Strix aluco), morph-specific differences in offspring growth reflect differences in parental effort, but empirical evidence linking behaviour, diet and breeding success across populations is limited. Here, we compare parental care, food provisioning and activity rhythm in two ecologically comparable northern European populations inhabiting mixed boreal forest landscapes in Finland and Sweden.

Parental behaviour was monitored using infrared trail cameras during three breeding seasons (2022-2024) recording adult nest attendance, incubation and brooding bouts and prey delivery before and after hatching. Prey remains were collected and sorted to estimate prey biomass, diet composition and prey diversity. Behavioural and diet metrics were combined into parental effort indices and related to fledging success.

Preliminary analysis indicate that overall parental effort does not differ substantially between populations and is not strongly predicted by habitat composition or prey biomass. Fledging success, however, increases with higher prey diversity, independent of country. Diet composition differs between populations despite comparable overall diversity, suggesting local prey communities have a primary role in defining diet. Diel prey delivery patterns are similar between populations, with strongly nocturnal and overlapping activity rhythms.

These results suggest that while the parental care behaviour is broadly conserved, variation in diet composition and diversity may be more closely linked to reproductive outcomes than parental effort alone. This study highlights the role of ecological context in shaping reproductive strategies across populations.

Parental care enhances offspring fitness but imposes costs on reproduction and survival of caregivers, which favours strategic resource allocation among offspring to maximise fitness. Such decisions should rely on information provided by offspring through signals of quality, dependent on environmental conditions during breeding (linked to food availability and thus, e.g. to carotenoid intake), and signals of need, which reflect individual condition and may be influenced by immunological challenges like ectoparasite infestations. Despite long-standing interest in how offspring traits shape parental behaviour, it remains unclear how parents integrate these different signals when provisioning their brood.

Using carotenoid supplementation to manipulate signals of quality, along with natural variation in ectoparasite load as a proxy for signals of need, we first confirmed that mouth colour reflects carotenoid availability and functions as a signal of quality, while mite load influences begging intensity and thus acts as a signal of need. We then tested whether these signals affect parental behaviour at nest level (i.e. number of feeding trips), whether parents preferentially feed specific nestlings, and whether such favouritism influences nestling condition.

Neither signal type affected the total number of feeding trips, however, parental favouritism depended on nestling quality: control nestlings received a higher proportion of feeds, but only when paired with a carotenoid-treated nestmate. As all nestlings reached similar body condition despite of provisioning bias, this pattern may indicate that parents favour lower-quality nestlings to maximise overall brood viability, but only when within-brood quality differences exist. Overall, these results suggest that signals of quality, rather than signals of need, determine parental favouritism, which is flexible and context-dependent, potentially providing parents an advantage in the parent-offspring conflict.

Fitness is shaped by the pace of reproduction and the trade-offs in parental investment allocated between current and future offspring. Using a unique and comprehensive 11-year longitudinal dataset comprising 362 pregnancies from 117 wild female mandrills (Mandrillus sphinx), we investigated how reproductive strategies influence maternal investment decisions and their consequences for both current and future reproductive outcomes. Our findings reveal that when females shift investment away from current infant care to prioritize a new gestation, they face elevated mother-infant behavioral conflict. This conflict significantly increases the likelihood of fetal loss, thereby reducing short-term reproductive success. The mother-infant conflict appears to act as a physiological or behavioral barrier to efficiently reallocating maternal resources toward the developing fetus. Alternatively, it may trigger a strategic termination of pregnancy, serving as an adaptive response to mitigate the fitness costs associated with short inter-birth intervals, such as the risk of losing a dependent infant. Notably, females who experienced fetal loss subsequently demonstrated higher long-term reproductive success compared to those who carried an infant to term but whose offspring died at a young age. These results uncover a previously hidden adaptive mechanism that appears to regulate the timing of female reproduction in a way that maximizes lifetime fitness. Understanding how mother-offspring conflict influences reproductive scheduling in mandrills provides valuable comparative insight into how analogous conflicts might have shaped human reproductive strategies, including decisions around pregnancy spacing, investment allocation, and the occurrence of pregnancy loss under specific ecological or social conditions. This comparative approach enhances our understanding of the evolutionary continuity and divergence in reproductive strategies across primates.

In sequential hermaphrodites, individuals function as one sex early in life and the other sex later in life, creating a unique optimization problem. It remains an open question whether selection has favored individuals that function well as both sexes (Hypothesis 1) or whether there is sexual antagonism such that individuals that function well as one sex function poorly as the other (Hypothesis 2). Here, we test these two alternatives by investigating personality and plasticity of parental effort across male-to-female sex change in the clown anemonefish, Amphiprion percula. Clown anemonefish live in small social groups consisting of a dominant breeding pair and a limited number of non-breeders. The breeding pair exhibits biparental care, with both sexes investing time in tending to clutches. In the event of the death of the breeding female, the male will change sex to become the new dominant breeding female, while the largest resident non-breeder will become the breeding male. To test our two hypotheses, we conducted a year-long field study in Kimbe Bay, Papua New Guinea. We removed breeding females from 15 groups, experimentally inducing 15 cases of sex change; females naturally disappeared from more groups, resulting in 4 more cases of sex change. We measured parental effort by filming and scoring one-hour parental care videos of individuals before sex change when they were functioning as a male and after sex change when they were functioning as a female. Our results illustrate and quantify individual personality and plasticity of parental effort across sex change using reaction norms and mixed model analysis, respectively. This study is the first to investigate personality and plasticity in parental effort across sex change, providing new insights into sexual antagonism and how selection operates across life history stages.

Changing climates, anthropogenic disturbances, and invasive species may impact the predictability of resource availability. Consequently, species may be faced with increased uncertainty of reward (e.g., inability to predict foraging outcomes due to incomplete information), impacting their ability to make optimal foraging decisions. Neophobia (aversion to novelty) has been proposed to enable animals to cope with uncertain predation risks, but it remains unclear whether this also applies to uncertain rewarding contexts. We address this with in-situ supplementation experiments in a wild population of eastern chipmunks (Tamias striatus) in the Montagnes Vertes reserve (Estrie, Quebec), where beech bark disease is rapidly impacting resource availability due to the invasive beech scale (Cryptococcus fagisuga). Daily access to feeders containing ad-libidum novel food was manipulated over three phases, such that all feeders were initially accessible in a temporally predictable manner, followed by half remaining predictable and half becoming temporally unpredictable, followed by all feeders becoming predictable again. We assessed neophobia (latencies to enter the novel feeders) and exploitation (change in visitation rate and seed consumption) based on feeder predictability. Chipmunks did not alter their seed consumption or daily visitation rate across phases, regardless of feeder treatments. Chipmunks also seemed to generalize feeder accessibility, visiting all feeders marginally more when the predictable feeders were open during the mixed predictability phase. Given that temporal fluctuations of resource abundance shape population dynamics and individual differences in exploration profiles in this species, this work highlights how individual behavioural differences may result in nuanced population-level consequences of anthropogenically introduced species or altered resources.

Pollinator foraging behavior generates acoustic cues accompanying flower visitation, yet the ecological relevance of these signals for plant-pollinator interactions remains poorly understood. Flying pollinators produce species-specific acoustic signatures reflecting visitation patterns and movement dynamics. Here, we test whether pollinator-generated sounds act as biologically meaningful cues capable of modulating floral responses, thus influencing pollinator behavior.

This study is embedded within the “Good Vibes” project (funded by HFSP) and focuses on natural populations of snapdragon (Antirrhinum litigiosum) in Valencia (Spain). Pollinator surveys conducted over two flowering seasons identified the solitary bee, Rhodanthidium sticticum, as the dominant pollinator. Its acoustic emissions were recorded during flight and used to play back realistic pollinator soundscapes under controlled phytotron conditions.

Plants were exposed to different acoustic treatments: silence, pink noise, playback of R. sticticum flight sounds, and playback of Bombus terrestris flight sounds, a secondary flower visitor, capable of nectar robbing. Nectar traits were measured after sound exposures of different durations. Plants exposed to R. sticticum sounds showed a significant increase in glucose, fructose, and sucrose concentrations after ten minutes. In contrast, pink noise, silence, and B. terrestris sounds did not induce such increases, and nectar sugar concentration decreased over time.

In addition, behavioral experiments showed that pollinators display a higher probability of feeding and ingest larger volumes when offered nectar mimicking the sugar concentrations produced by plants following playback of the primary pollinator. These results indicate that sound-induced modulation of nectar rewards can influence pollinator feeding decisions and may contribute to increased visitation persistence and fidelity, pointing to a sound-mediated feedback loop in plant-pollinator interaction.

The consumption of palm hearts by wild primates is rarely documented although palms are widespread in tropical forests. In the Brazilian Atlantic Forest, black-horned capuchin monkeys (Sapajus cucullatus) have been observed extracting the heart of the juçara (Euterpe edulis), a destructive behaviour that results in the death of this keystone and Largely Depleted species. The decision to exploit this resource appears to reflect an adaptive trade-off, involving substantial effort to obtain a food rich in water and fibre but low in energy. In this study, we investigated whether capuchins consume juçara palm hearts as an alternative resource during periods of preferred food scarcity, and whether palm heart extraction follows an optimisation process balancing the costs (i.e. number of leaves removed) and benefits (i.e. palm heart mass). We also evaluated palm heart selection and extraction efficiency in relation to sex and age class. We found a strong seasonal pattern, with 94% of extraction events occurring during the dry season, and the study group predating up to 67 juçaras in a single day. E. edulis palm heart emerged as a key dietary resource during this period, contributing substantially to herbivory when frugivory was reduced. Adult and subadult males accounted for most extraction events, targeting larger palms to maximize energetic return, whereas juveniles predated smaller palms with limited reward, and females rarely engaged in palm heart extraction. Observations of immature individuals attending extraction events suggest that social learning contributes to this behaviour, which may have a cultural dimension. Overall, palm heart consumption in S. cucullatus appears to be an opportunistic, seasonally constrained fallback strategy. It is now essential to determine whether this adaptive behaviour, even in a preserved environment, may have negative consequences on juçara populations, under current and future scenarios of habitat degradation and climate change.

There is often a discrepancy between animal behaviour observed in the wild and in laboratory settings, and this is particularly striking in discounting tasks. Animals devalue delayed food rewards by half after mere seconds in laboratory discounting tasks, yet regularly invest considerable amounts of time searching for and exploiting food items in natural environments. This divergence in behaviour has led to questions regarding the degree to which these laboratory discounting tasks are ecologically valid. We addressed this question using theoretical predictions and empirical tests. We will present predictions from a state-dependent dynamic programming model showing that steep rejection for delayed rewards is an artefact of an artificial testing environment, where animals can afford to be more selective due to reduced competition, reduced predation risk, and higher food availability. We will then support the model’s predictions with empirical data from a study of free-living grey squirrels (Sciurus carolinensis). We used an ecologically relevant investment measure, the maximum depth to which they would dig for a food reward and investigated how performance in this task was related to natural caching behaviour. As predicted by the model, we found that squirrels invested considerable time and effort into the ecologically relevant digging task conducted in their natural environment. We further found that squirrels who invested more in the task invested significantly more time digging and covering their food caches, and significantly less time eating during the October caching peak, prioritising the future over more immediate outcomes. Our results provide important empirical evidence of a link between temporal preferences and caching behaviour and further illustrate that animals’ performance in discounting tasks aligns with natural foraging behaviour when tested in ecologically relevant ways.

Globally, coral reefs are shifting to algae-dominated states, compromising biodiversity and ecosystem services. Nowhere is this transition unfolding faster than in the Caribbean, where it is imperative to identify and protect key drivers of reef resilience. One such potential driver is the cleaner goby Elacatinus evelynae, which removes ectoparasites from a diverse pool of client fish. In the Indo-Pacific, similar cleaning mutualisms involving cleaner wrasses increase fish abundance and richness around cleaning stations, driven by clients’ demand for such services and the reduced predation risk observed in these areas. As many of their clients are herbivorous, cleaners may also indirectly curb algal overgrowth by concentrating grazing activity. However, evidence for such community-level effects and trophic cascades is scarce in the Caribbean, where reefs present a different backdrop: they are more degraded, less diverse, and host a distinct assemblage of herbivores. In Curaçao, Netherlands Antilles, we explored how the presence of cleaner gobies alters fish community composition and perceived predation risk, and whether this alters herbivore concentrations and grazing near cleaning stations. Over one year, we removed all cleaner gobies from 8 out of 16 patch reefs and monitored biodiversity, fish biomass, grazing behaviour, and other ecological effects using stationary Stereo-Video Systems, Stereo-DOV surveys, Structure-from-Motion modelling, parasite traps, and algae deployments. Our results suggest that reefs with cleaner gobies not only host higher fish and herbivore abundance but may drive shifts in grazing behaviour. We present, for the first time in the Caribbean, evidence that herbivores feed further from the reef when E. evelynae are present. Given the sharp decline of the region’s reefs and herbivore populations, our findings illuminate a potential much-needed pathway aiding the limitation of algal growth and strengthening reef resilience in the region.

Juvenile birds develop in a social environment where communication is key, both within the family and later in broader social contexts. It has therefore been proposed that mothers may prenatally prepare their offspring for these environments through maternal effects, such as the allocation of hormones to eggs. Previous studies suggest that higher maternal androgen allocation may be favoured in more competitive social environments, but comparative evidence remains scarce. Here, we investigated whether interspecific variation in sociability is associated with prenatal maternal hormone allocation in birds. We conducted a comparative study using published data on yolk hormone concentrations (testosterone, androstenedione, oestradiol, and corticosterone) across avian species (24 ≤ n ≤ 144, depending on the hormone considered). For each species, we compiled information on social traits (coloniality during breeding, winter gregariousness, cooperative breeding), life-history characteristics (clutch size, female body mass, developmental mode), and ecological traits (nest type). Phylogenetically controlled Bayesian mixed models were used to test whether social traits predict maternal hormone allocation. Our analyses show that colonial species transfer more androgens to eggs than non-colonial species, consistent with previous evidence and with the hypothesis that prenatal androgen exposure facilitates development in competitive social environments. In contrast, colonial species allocate less oestradiol, which may be linked to the regulation of social signals, for example via effects on juvenile coloration. Additionally, species breeding in closed nests transfer more corticosterone than species with open nests. Overall, our results suggest that maternal hormone allocation to eggs covaries with species-specific social environments, potentially shaping offspring phenotypes in ways that are adaptive to postnatal conditions.

The capacity of animals to navigate highly complex spatial environments is critical for their reproduction and survival, as it enables them to find food, locate mates, patrol and return to their territories and home ranges, and migrate to (seasonal) habitats. To provide and gather information about dynamic targets, animals commonly make use of social information provided by others, and a particularly widespread example of such social information transfer is the production and use of trails. Trails are paths in the environment, created through sequential acts that alter the substrate and provide information to others. We focus on additive trails, in which material such as pheromones, or mucus are added to the environment. Trails provide many adaptive benefits to the trail producer (and follower), from eased movement, guidance to resources, to information transfer of innate states. However, trails are costly to produce, and can be eavesdropped on by predators or parasites.

The multifaceted usages of trail following make it a common foraging, mate search and/or navigation strategy in many different taxa. Perhaps the most intriguing aspect of trail use is the addition of directionality information to a trail that aids in determining the direction in which it was laid. However, adding directionality to trails is non-trivial. Trail directionality has rarely been described, and elucidation of the mechanism behind directionality is even rarer. The relative rarity of this apparently overwhelmingly useful trait is highly puzzling.

We present a conceptual review of the use of additive terrestrial and (semi-) aquatic chemical trails, and use this as the basis from which to build a taxonomy of trail functions. We review occurrences and functions of, and means to experimentally investigate trail-following across taxa. This review aims to reinvigorate this fascinating aspect of behavioural ecology, and provide a firm footing from which to explore further.

Intrasexual competition for mates among males may favor male traits that disrupt the sexual signals of females. Across many animals females attract males using chemical sexual signals (sex pheromones), a modality that is public and susceptible to manipulation. For example, Latrodectus tredecimguttatus, black widow spider females deposit sex pheromone onto their webs that slowly converts to mate-attracting volatiles. Upon arrival, a male courts the female by bundling up her web with his own silk. The bundled up web is no longer attractive to rival mates. To determine the mechanism behind the loss of attractiveness, we tested three alternative hypotheses: 1. Mechanical reduction hypothesis: Bundling of the female web physically reduces the available evaporation surface for the pheromone. 2. Chemical inhibition hypothesis: Male silk contains pheromones that biochemically suppresses the conversion and release of mate-attractants. 3. The deterrence signal hypothesis: the addition of a rival-deterring ‘anti-aphrodisiac’ pheromone despite female pheromone emission. To test these hypotheses, we presented males in dual choice olfactometers with the scent of female webs that were either intact, experimentally bundled up (mechanical control), bundled up by males, or derived from unattractive immature females. Furthermore, we chemically extracted these webs and analyzed them using high-resolution liquid chromatography coupled with mass spectrometry (HR-LC-MS). We employed targeted and non-targeted metabolomics to compare pheromone conversion rates and identify potential male-derived pheromone candidates. Our results support the hypothesis that a male pheromone renders female webs unattractive beyond simple mechanical occlusion. Our study sheds light on how male-male competition results in modification of intersexual signals at the cost of females.

Olfaction is a powerful driver of sexual communication in many mammalian taxa, including primates. While previous research has examined the rate at which individuals deposit odours (i.e., scent-marking), less is known about the behavioural responses these cues elicit. We hypothesised that olfaction contributes to primate reproduction by facilitating mate attraction and mediating competition. Accordingly, we expected breeding males to show stronger responses to scent marks deposited by breeding females. We studied a group of wild saddleback tamarins (Leontocebus weddelli). During behavioural follows, we recorded responses to each scent-marking event observed. Responses were classified as investigatory (sniffing or licking the mark) or overmarking (depositing a new scent mark that blends with or covers the previous one). We found that the breeding female received significantly more responses to her scent marks than any other group member (z = 5.25, p < 0.01). Breeding males also responded with overmarking to other males less often than they overmarked the breeding female’s scent marks (z = –2.31, p = 0.021). The observed sex bias in responses may reflect the fact that males are more attentive to the scent marks of the breeding female, perhaps gathering information on fertility and communicating their association with the female through overmarking. Our findings reveal sex-specific differences in scent-marking responses, highlighting a reproductive role for olfactory communication. Together, our results contribute to recognising primate olfaction as a potentially important target of sexual selection.

Sea lamprey (Petromyzon marinus) rely on chemical cues to mediate their anadromous life history, especially during their terminal spawning phase to coordinate migration and reproduction. Ovulated females locate mates using a multi-component sex pheromone released continuously across male gills and pulsed chemical cues in milt (fish semen). Both odors guide female discrimination among potential mates. Sea lamprey milt contains chemical cues that broadly attracts adults across multiple maturation stages and sexes. Spermine was identified as a component of the milt-derived pheromone that activated a receptor in the olfactory epithelium and attracted specifically ovulated females but not males or migratory females, indicating other compounds mediate broader attraction to milt. To test this hypothesis and search for additional bioactive components in milt, we used mass spectrometry and detected C14 and C20 ceramide, which are ubiquitous lipids involved in membrane dynamics and cellular signaling, in the seminal plasma of milt at biologically relevant concentrations, but not in other waterborne sources. Sub-picomolar concentrations of these ceramides stimulated the adult sea lamprey olfactory system in electro-olfactogram recordings. Flume assays revealed C14 and C20 ceramide attracted migratory and mature male and female lamprey. Ready-to-spawn females may use milt-derived cues to identify actively spawning males, whereas males and migratory females, which are limited to a single spawning season, may use it to locate the lek-like aggregations with ongoing reproduction and nesting habitat. Based on chemical, physiological, and behavioral evidence, this study expands the known fish pheromone repertoire to include ceramides, highlighting the relevance of lipid-based signaling in vertebrate reproductive ecology. These findings may also inform strategies for managing invasive sea lamprey in the Laurentian Great Lakes and conserving imperiled populations in their native range.

The evolution of cooperative breeding is often attributed to factors facilitating increased inclusive fitness benefits such as family living and genetic monogamy. Yet, many species of cooperatively breeding birds live in groups with low relatedness and/or have extraordinarily high levels of extra-pair paternity (EPP). The resulting extrapair young (EPY) can alter the patterns of relatedness of the group and change the cost and benefits associated with cooperation. Patterns of relatedness within the group can also affect patterns of EPP; individuals in groups with high-relatedness should seek extra-pair copulations (EPC) outside of their group, while individuals in groups with low-relatedness can seek EPC with group members. To explore these relationships, we study the variegated fairywren, Malurus lamberti, a cooperatively breeding bird with multiple breeding pairs that have low intragroup relatedness and have high levels of EPP. We compared the patterns of EPP of females in different social roles and with varying relatedness to group members. We found no significant difference between the proportion of young sired by EPP for dominate females and subordinate females. While the majority of EPP by dominate females was due to extragroup EPP, subordinate females had a similar proportion of EPP resulting from extragroup EPP and withingroup EPP. Moreover, the proportion of extragroup EPY increased as average relatedness between the female and the male group members increased. Lastly, females in incestuous pairs only had EPY. These results provide insights into how females’ social landscapes influence mating patterns in a complex cooperative system.

Animal social networks have profound effects on fitness, yet they are difficult to observe and quantify in the wild. Here, we show that microbial transmission can be used to reconstruct the social networks of wild rock hyraxes (Procavia capensis) across multiple temporal scales. We collected fecal samples from marked individuals and performed shotgun metagenomic sequencing. From these data, we assembled microbial genomes, identifying a high proportion of previously undescribed bacterial taxa. For bacterial species present in multiple individuals, we reconstructed phylogenetic relationships and inferred cases of strain transmission, revealing long-term social associations. For example, a male that had dispersed from its natal group continued to share most of its bacterial strains with members of its previous group. Applying a similar approach to DNA viruses instead captured short-term transmission patterns: the same male predominantly shared viral strains with members of its current group. Together, these results demonstrate that different classes of microbes capture distinct temporal layers of animal social networks. More broadly, they highlight a central role for social interactions in structuring microbiomes at the levels of individuals, groups, and populations, with important implications for ecology and evolution.

About 50 years ago, Rohwer developed the “badge of status” hypothesis to explain variation in plumage coloration in wintering Harris’s sparrows. The idea is simple: if traits like the intensity, size, or hue of color patches positively correlates with an individual’s fighting ability, they can function as signals reducing the need for costly aggressive contests. Since then, hundreds of studies have tested this hypothesis, expanding it across taxa across the phylogenetic tree and broadening its scope into the status signaling hypothesis. While common patterns have emerged, the complexity of the phenomenon has also become evident. The diversity of signals, pigments, sensory systems, and social interactions has resulted in many ways to test the hypothesis. It has also become clear that signaling may not only be condition-dependent, but may also reflect genetic quality or exploit sensory biases. Finally, we are only now uncovering the biochemical and physiological mechanisms of color traits, which often vary among taxa. Thus, although the badge of status hypothesis initially found support, its general validity has become unclear, to the point that even textbook examples—such as the house sparrow bib size—have been challenged. This calls for a re-evaluation of the hypothesis. Here, we present the results of a meta-analysis across bird species re-evaluating the correlation between dominance and badges of status, which reveals high heterogeneity, publication bias, and mixed support. In addition, we present a case study demonstrating how long-term longitudinal data and AI-powered data extraction enable the creation of large datasets and facilitate individual-level analyses. This approach reveals that while badges grow with age and dominance is correlated with age, badges themselves are not correlated with dominance. We argue that we are now in a position to develop clear guidelines for data collection to determine whether, and in which systems, badges of status are used.

For many gregarious species, socially integrated individuals tend to have higher fitness, often in the form of improved survival. However, the mechanisms driving these relationships remain uncertain. One commonly proposed mechanism is that well-integrated individuals can benefit by being tolerated in a group and therefore, have reduced predation risk, though data explicitly testing this are limited. It is also important to consider that forming social relationships takes time and other antipredator behaviours can also change with age. Studies detailing the ontogeny of such behaviours are rare in the wild, partly due to the difficulty of following individuals throughout development. European rabbits are an ideal system to understand how social and antipredator behaviours develop as they are short lived, fast-maturing and have high natural predation risk. To understand how perception of risk and social decisions change with age, we monitored a population of wild European rabbits from emergence to maturity. Using these data, we quantify the morphological, behavioural, and social ontogeny of wild rabbits. We show how rabbit social behaviour changes with age, and how this links to their perception of predation risk. This work has important consequences for our understanding of social and antipredator behaviours in this system and how these arise as individuals approach maturity.

Early-life conditions can have short and long-lasting effects on offspring fitness and, ultimately, predict adult performance. These early-life conditions are shaped by local socio-ecological aspects of the environment,and can interact with broader, large-scale environmental factors. Investigating how these complex patterns drive variation in fitness can shed light on the links between ecology and evolution in natural populations. Using long-term data from a free-living common tern (Sterna hirundo) colony, we analysed the effects of local breeding density under varying population sizes, predation events and fish availability on a suite of early- and late-life fitness proxies. These proxies include hatching success, chick age at death, fledgling mass and probability, probability and age of returning to the colony, as well as recruitment probability and age. We expected the effect of early-life conditions on fitness to decrease as chicks grow older, so that early-life fitness proxies such as chick age at death and fledgling mass would be more strongly correlated with local breeding density. Furthermore, we expected these responses to change depending on fluctuating large-scale environmental conditions. Our analyses revealed a negative effect of local breeding density on all early-life fitness proxies excluding hatching success, these effects being generally stronger in years with bad environmental conditions. Overall, these results suggest that individual fitness can be largely shaped by the social environment experienced early in life in combination with large-scale ecological factors. How variation in these fitness responses ultimately influences population dynamics remains to be explored.

Animal groups with fission-fusion dynamics allow individuals to balance their own energetic and social trade-offs by ranging in subgroups of varying sizes and compositions . For females, such trade-offs shift across reproductive stages. During lactation, mammals face substantial energetic constraints that gradually relax as offspring become nutritionally independent. With increasing offspring age, the benefits of socialization for offspring may favor maternal social association with more group members. We tested the hypothesis that mothers change their gregariousness across lactation in response to offspring age and their own energetic condition in a population of wild bonobos. We predicted that mothers in the energetically demanding phase of early lactation, when benefits of socialization are limited, avoid large subgroups particularly when in poor energetic condition . As offspring age, we expected mothers to join large subgroups to gain social benefits for themselves and their offspring, despite higher energetic costs. We analyzed female gregariousness and urinary C-peptide, a biomarker of energetic balance, in 20 mothers (offspring 2 weeks-4 years old) over 8 years. Using linear mixed effects models, we found that a mother’s relationship between party size and energetic balance depended on offspring age. For mothers with young offspring, energetic balance was positively associated with party size, consistent with avoidance of large parties when in poor energetic condition. For mothers with older, increasingly independent offspring, energetic balance was negatively correlated with party size, suggesting that these mothers tolerated or even prioritized the benefits of large groups despite their greater energetic costs. Our results demonstrate how mothers make context-dependent social decisions to balance fluctuating costs and benefits across lactation.

Humans worldwide kill prey at much higher rates than other predators making humans a uniquely lethal global “super predator”. A growing body of experiments reports that wildlife fear humans far more than any other predator, but all studies have been conducted in locations or on species that are subject to human hunting. Barro Colorado Island (BCI; 15.6 km2) –created as part of the Panama Canal in 1914 and a nature monument since 1923– provided us with a unique opportunity to examine fear of humans where human hunting of wildlife has not existed for nearly four decades (generations before any of the animals in our study were born), and the wildlife are instead hyper-exposed to “benign” human presence, with thousands of scientists, staff and ecotourists residing or visiting annually. We experimentally tested whether relaxed selection and habituation to humans have eliminated the fear of humans for the most common mammals on BCI (N = 8 species), by measuring their responses to playbacks of humans compared to those of jaguars (historically the non-human apex predator in the region) and non-predator controls (birds or frogs), using automated camera-speakers (Automated Behavioral Response systems; ABRs). Our results demonstrate that, as a whole, the community of mammals on BCI still fears humans. Upon hearing human playbacks, the wildlife community fled 2.1 and 16.5 times more often and abandoned their location 16% and 23% faster than in response to jaguar and control playbacks, respectively. The community also feared jaguars and fled 7.8 times more often compared to control playbacks. Similar responses were found when considering species individually. Experimentally demonstrating that fear of humans is deeply ingrained in wildlife—even in a context where humans pose no actual danger—is critical to revealing our evolutionary historical role as apex predators and adds a new evolutionary dimension to our worldwide environmental impacts.

13 13. Acoustic communication

Natural light cycles are a foundational driver of organismal behavior. However, the global extent and ecological novelty of artificial light at night (ALAN) mask important natural light cues resulting in ALAN being a key component of anthropogenic change. The congregation of flying insects around artificial light sources, named flight-to-light behavior (FLB), is central to the impact of ALAN on insect behavior. FLB is the easily observable result of ALAN misdirecting insects’ dorsal-light-response; a behavior in which flying insects orient their dorsal surface to the brightest visual region. In natural light environments the brightest region is the sky, but this vertical light profile is altered by ALAN. Research on FLB has often focused on the effect of ALAN in isolation, but insects do not encounter light sources in spatiotemporally homogenous conditions. In this project, I utilize mark-release-recapture trials to measure the relative strength of FLB in moths under different light environments, described by three landscape-scale factors: artificial skyglow, habitat canopy structure, and the lunar cycle. Moth FLB to a focal light source is measured at three distances (2, 5, 10 m) under different landscape conditions (habitat: open or closed canopy; skyglow: urban or natural; lunar phase: full or new). Artificial skyglow reduces FLB (recap rate: skyglow, 3%; no skyglow 13%), in addition to previously documented effect of moonlight (recap rate: full moon, 6%; new moon, 14%). The effect of light environment on FLB is primarily observable within 5 meters; recapture rates were uniformly low at 10 m. The effect of downwelling irradiance (skyglow or moonlight) on FLB is stronger in open habitats (∆ recap rate [low – high irradiance]: open canopy, 13%; closed canopy, 5%). Thus, misdirection of moths’ dorsal light response by artificial light sources depends not only on innate behavior but also landscape structure, lunar phase, and the built environment.

Carnivore predation on livestock and subsequent retaliatory hunting remain major obstacles to human–carnivore coexistence worldwide. Understanding how wildlife behavior responds to human activities and livestock protection strategies is essential for conservation and management. From April 2023 to March 2024, we deployed 96 camera traps across two adjacent ranches in the Patagonian steppe of Argentina—one active (La Sofia) and one abandoned (La Herradura)—to examine how humans, livestock, and livestock-guarding dogs (LGDs) influence interactions among pumas, prey, and mesocarnivores. We analyzed fine-scale time-to-event data, spatial patterns using photocapture rates, and diel activity to assess human effects on predator–prey dynamics. Puma detections were 50% higher on the abandoned ranch, where pumas were more likely to appear following prey or mesocarnivore detections, suggesting a more intact trophic system. On the active ranch, pumas exhibited strong reactive avoidance of humans, LGDs, and sheep: following human or LGD detections, puma return rates were approximately 100 times slower than those of prey and mesocarnivores (hazard ratio = 0.01), and 250 times slower following sheep detections (hazard ratio = 0.004). Humans, LGDs, and sheep were concentrated near ranch infrastructure. Prey had higher photocapture rates on the active ranch, consistent with a potential human-shield effect in which prey exploit human presence as refuge, indicating that puma fear of humans may outweigh prey-tracking behavior. Diel activity patterns were broadly similar between ranches, though guanacos were slightly more active throughout the day on the active ranch, possibly reflecting increased foraging time in areas with sheep. These findings demonstrate how human activity modulates spatiotemporal trophic interactions and highlight how conflict-mitigation strategies such as LGDs and active herding can support coexistence.

Cities drastically transform habitats worldwide, exposing animals to novel ecological conditions that can alter the frequency and nature of their social interactions. For example, dense built infrastructure and patchy resource distributions may constrain movement and promote increased encounters among conspecifics, which can impose unique social challenges. Despite the important consequences that disruptions to a species' social system might have, few studies have addressed the impact of urbanization on social behaviour. Moreover, although most of these studies report a significant impact, they have focused almost exclusively on highly social species. This raises a critical question: does urbanization affect animal social systems to the extent that even less-social species are impacted?

Here, we investigate how urbanization influences social behaviour in the Common wall lizard (Podarcis muralis), a territorial species and successful urban dweller. Using social network analysis, we found that urban lizards had more social connections, stronger associations and were observed in more associations overall. This indicates urban lizards are more socially tolerant than non-urban lizards. Interestingly, these differences were not explained by variation in population density. We suggest the increased sociality could be due to spatial constraints and resource heterogeneity in urban habitats. Our findings have two major implications: they suggest that shifts in social strategies may facilitate persistence in urban landscapes, and reveal that urbanization can reshape social behaviour even in species that are considered less-social.

As the demand for medications continues to rise globally, pharmaceutical pollution is increasingly recognized as a growing environmental threat. Venlafaxine, a commonly prescribed antidepressant, has emerged as one of the most pervasive pharmaceutical pollutants in aquatic environments. As a psychoactive pharmaceutical, venlafaxine can alter key behavioral traits, such as activity and boldness, with cascading consequences on vital ecological processes. For instance, the effects of pollutants are species-specific, with invaders often showing higher tolerance to pollution in comparison to native species, potentially enhancing their competitive advantage and invasion success. Despite these alarming consequences, the impacts of chemical pollution on native-invasive species interactions remain unexplored. Our study therefore aimed to investigate whether exposure to environmentally realistic concentrations of venlafaxine affected behavior and interactions among the southern pygmy perch (Nannoperca australis), a small freshwater fish native to Australia, and the invasive eastern mosquitofish (Gambusia holbrooki). Fish were exposed for 28 days to either a freshwater control (i.e., no venlafaxine) or to venlafaxine at low and high concentrations reflective of levels found in the wild. Following the exposure period, fish were matched with a heterospecific from the same exposure treatment, and assayed together to test their activity, aggression, and foraging behaviors in the presence of a competitor. Our results show that perch exposed to venlafaxine showed reduced between-individual variation in their activity compared to perch in the control. Perch in the high-exposure treatment also approached mosquitofish more frequently than controls. In contrast, there was no effect of venlafaxine exposure on any measured traits in mosquitofish. Overall, our findings suggest that native southern pygmy perch are more vulnerable to the effects of venlafaxine than an invasive competitor.

Urban expansion has made artificial light at night (ALAN) a growing concern. Its adverse effects on activity patterns have been highlighted for many species across a wide range of taxa, including several bird species. Yet, its effects on nocturnal birds remain poorly documented, particularly at fine behavioural and physiological scales. In this study, we investigated how ALAN at nest entrance affects parental behaviour and corticosterone levels in breeding barn owls (Tyto alba) using a multi-method approach. For this purpose, a light source mimicking a streetlamp was installed at nest entrances, and we monitored behavioural responses (time spent near the entrance, timing of first nightly visit, …) and physiological stress (baseline and stress-induced corticosterone levels).

When nest entrance was exposed to ALAN, both breeding adults tended to delay their first visit at night. Males spent more time perching at the entrance under ALAN, whereas females showed the opposite trend. Stress-induced corticosterone naturally declined over the study period, but this decrease was absent in males at illuminated nests. Males at ALAN-exposed nests also showed a reduction in body mass. These results suggest that ALAN alters both behaviour and stress physiology, particularly in males, potentially reflecting increased vigilance. The impact of ALAN additionally shifted depending on moonlight intensity and owl colour morph.

Overall, our findings show that even localized light exposure at nest entrance can disrupt parental behaviour and physiological state in a nocturnal raptor. Given the global increase in ALAN, these changes may have important consequences for adult fitness and survival.

Pace-of-life theory suggests that different resolutions of the trade-off between current versus future reproduction reflect different "pace-of-life" strategies and that these strategies are mediated by one's behaviour (e.g. risk-taking personality), physiology (e.g. metabolic rate), and life-history (e.g. age of reproductive onset). These pace-of-life strategies vary among species, populations, and individuals, but the factors driving that variation remain unknown. Here, we test the hypothesis that competition drives variation in pace-of-life: we predict that competitive ability (γ) trades off with one's rate of reproduction without competition (R0) and thus, natural variation in competition drives variation in pace-of-life traits at multiple scales. To test this requires quantifying (co)variation in competition intensity (), competitive ability (γ), and the intrinsic rate of reproduction (R0) both among and within populations - necessitating complex statistical analysis and big data. In light of this challenge, we have developed Bayesian multi-level models using STAN and are applying them to a large collaborative dataset containing breeding information from 26 populations of great tits (Parus major) spanning 78 years and >80,000 breeding attempts. By applying these cutting-edge models to such a large dataset, we ensure the results we present will be conclusive and robust, helping to untangle the processes driving the evolution of variation in behaviour, physiology, and life-history across the biological hierarchy. Further, our methods can be used to tackle similar hypotheses about ecological drivers of phenotypic variation more broadly.

[Background] Animal personality is defined as consistent differences in how individuals respond to stimuli. In an unpredictable environment, personality is expected to be maintained by habitat variation. Personality-matching habitat choice will then lead individuals with similar personality types to be found in similar habitats. It is unclear what habitat characteristics contribute most to this personality-habitat association. [Materials and methods] Here, we examine the distribution pattern of a personality trait in the Great tit (Parus major) in relation to a series of breeding habitat characteristics. Habitat characteristics of all first clutches were measured within a 50-meter radius, which is considered the primary habitat utilising range for the breeding pair. For each breeding site, we measured habitat variables, including land use, the dominant tree species, the normalised difference vegetation index (NDVI), and two types of crowding pressure. To characterise multivariate habitat structure, a principal component analysis (PCA) was performed. [Results] Our results show apparent clustering of the habitat variables, indicating two to three axes. While we expected evidence for a non-random distribution of personality types across these environments throughout our 25 years of study, preliminary analyses do not appear to confirm this pattern across all environmental axes throughout this period. This would indicate that not all ecological habitat characteristics are equally important. [Prospect] We will discuss here the implications and point towards follow-up studies focusing on behavioural plasticity and the fitness consequences of personality-habitat matching. Since our research is conducted in an area affected by human activity, the results will be discussed in the light of studying selection on animal personality in human-modified habitats. This together will increase our understanding of how individual animals adapt to changing environments.

Understanding where behavioral individuality comes from is a fundamental question in biology. The long-standing assumption is that these consistent behavioral differences among individuals arise through a combination of among-individual variation in genes and environments. However, recent work has shown that even when minimizing such variation, individuality persists, questioning their obligatory role in generating individuality. Here, we used a unique animal system—the Amazon molly—to study the role of the most commonly proposed factor: genetic variation. Amazon mollies are a naturally clonal fish arising from a single hybridization event ~100,000 years ago between two sexual species: the Atlantic and Sailfin mollies. Amazons live in sympatry and share ecologies with their two parental species, making the only notable difference between them their amount of genetic variation among individuals. This provides an ideal opportunity to test the role of genetic variation in generating individuality. We tracked ecologically relevant behaviors of Amazon, Atlantic, and Sailfin mollies, reared in standardized conditions, continuously from birth for four weeks, to compare how high and low amounts of among-individual genetic variation shape individuality. If individuality depends on genetic variation, the sexual species should show greater among-individual differences than clonal Amazons. If not, individuality must be arising through other mechanisms. Surprisingly, individuality did not differ between sexual and clonal species, either in magnitude or temporal onset over development, indicating that it was generated by something other than genetic or environmental variation. Amazons may have unique means of generating individuality (e.g., solely from maternal effects), and/or individuality may be much less dependent on among-individual genetic variation than we previously thought. This unexpected result challenges age-old assumptions about what makes individuals unique.

Anthropogenic change is presenting animals with novel suites of multiple stressors where behavioral responses to rapid environmental change are likely to play a crucial role. However, aside from predation, little is known regarding key behavioral responses to these stressors, the extent of consistent individual variation and in particular, correlated behavioral responses (i.e., ‘Fear Generalization’). . Theory predicts that: a) animals may generalize their fear responses regardless of the nature of the danger; i.e., that ‘fear is fear’, b) that correlations may arise due to individual differences in developmental or social history, or c.) that differences in how threat cues are perceived may drive correlations. We present results from a series of experiments testing these non-mutually exclusive predictions. We first document differences in the structure of fear generalization across threats in focal invertebrate and vertebrate taxa, presenting new results on both the social and developmental drivers of fear generalization. Specifically, we find that: 1) conspecific aggression can drive stronger, correlated aversive responses to different environmental stressors via loser effects, and 2) that developmental exposure to either of two stressors drives stronger responses to both, and elicits behavioral correlations between the two stressors. We next present data on both neurobiological processes driving plasticity and overlapping neural activation in response to aversive cues, characterizing the interaction between the two in driving fear generalization across a suite of ecological stressors.

Ongoing climate change has drastic and diverse effects on organisms. In particular, warmer temperatures are assumed to accelerate the pace of life of individuals, and therefore developmental and senescence rate. Because behavioural traits and their among-individual variability are involved in eco-evolutionary dynamics, a better understanding of how climate is susceptible to alter their ontogeny is required. Here we focus on the effect of a warmer climate on the ontogeny in individual activity level in the common lizard Zootoca vivipara. Activity is more susceptible to changes in climate given its link with pace of life syndrome and metabolic rates and such changes may have strong consequences on population and community dynamics. For the last 10 years, common lizards are maintained in semi-natural mesocosms experiencing either current or ~2°C warmer climatic conditions and individually monitored for activity level and life history traits over their lifetime. Using this database, we explored how warmer climates impact age-related changes in the mean and the within and between individuals variability of activity levels as well as the mechanisms potentially involved in such changes (differential survival and plasticity). We found activity to be partly heritable and repeatable only on parts of the lifetime resulting from contrasting patterns of between and within individuals variability across ages and climates. We found that activity level decreased with age, both as a result of within-individual changes and of the selective disappearance of more active individuals, more pronounced in the warmer climate. Overall, the syndrome linking activity level and fitness outcomes was climate-dependent, mostly because only less active individuals accelerated their pace-of-life in warmer climates. Considering its close links with physiology and pace of life syndromes, observed changes of the ontogeny of activity with climate may have consequences on the population dynamics.

The life-history trade-off hypothesis predicts individuals to adjust risk-taking behaviour to expected future fitness (residual reproductive value, RRV). The higher an individual’s RRV the lower its risk-taking. However, risk-taking and survival are condition-dependent and hence body condition should mediate the relationship between risk-taking and RRV. Iteroparous species with overlapping generations are an ideal system to test these predictions because individuals with different RRV can co-occur under the same environmental conditions. Here we quantified boldness and activity in repeated behavioural tests and risk-taking during foraging in wild-caught common voles (Microtus arvalis, n = 31) of two cohorts during autumn: the parous summer cohort and the nulliparous autumn cohort and related risk-taking behaviour to body condition. Whereas individuals of the summer cohort took higher risks the more favourable their body condition, the pattern was reversed for the autumn cohort. This pattern suggests that individuals with higher RRV (nulliparous autumn cohort) protected their body condition and traded resource gain for safety, but only if their body condition was unfavourable. Thus, if individuals need to survive the winter to gain reproductive success, they show behaviour concordant with predictions of the asset protection principle. If individuals already reproduced (summer cohorts) but could still increase their reproductive success, their behaviour is concordant with the state-dependent safety hypothesis. These differences were also reflected in the relationship between boldness and risk-taking during foraging: only in the summer cohort, bold individuals perceived high risk and had lower resource exploitation, when their body condition was unfavourable, but perceived lower risk when their body condition was favourable and vice versa in shy individuals. Thus, individuals do adjust risk-taking to expected future fitness, but this adjustment is condition-dependent.

A vocal signal is considered honest if it provides accurate information about the signaller’s characteristics. Evolutionarily stable strategy models suggest that signals must only be honest on average, allowing dishonesty to occur at low frequencies. Several empirical examples support this idea notably in male green frogs (Rana clamitans), where smaller individuals lower the frequency of their calls to mimic larger males, displaying dishonest signals. Rock hyraxes (Procavia capensis) are social mammals living in groups that usually contain a single resident male, several females, and juveniles, while bachelor males remain at the periphery. All male hyraxes produce long-distance vocalizations, termed songs. In the past we showed that solo songs are associated with the singer’s traits making them an honest signal. Male hyraxes sometimes respond to other male songs, termed counter-singing. Some of the characteristics of counter-songs are different than solo songs, raising questions about their honesty. The aim of this study is to test the honesty of counter-songs and determine whether it is related to singer characteristics. Following the results from male green frogs, we expected that lower-quality males (e.g. bachelor status) would be more likely to be dishonest than high-quality male (e.g. resident status). We analysed over 129 solo and counter-songs belonging to 18 males over 23 years we found that resident males were generally honest, and both solo and counter-songs displayed similar relationship to individual traits. On the other hand, bachelor males displayed dishonesty, with counter-song displaying the opposite relationship to individual parameters, either exaggerating or reducing acoustic features (e.g., frequency and amplitude), compared to their solo songs. These results suggest that male residency status plays a key role in shaping honesty-related strategies that may reflect broader patterns relevant to other social species.

Many animals use a variety of vocalizations to communicate with others and coordinate activities. However, animals are limited in the number of sounds they can produce. In humans, language allows for the unrestricted communication of information by generating new meaning from the finite set of sounds. For non-human animals, some level of combinatoriality has been observed such that segments of sound can be combined at either one of two levels, within calls or between calls. More rarely has it been examined how combinatoriality develops. Here we study how pūkeko (Ralidae, Porphyrio melanotus melanotus), a non-vocal learning bird species, develop combinatoriality in their acoustic signals across ontogeny. We recorded the vocalizations produced by embryos, chicks, juveniles and adults in and around 19 wild pūkeko nests. We recorded the first vocalizations a couple of days prior to hatching and found that embryos and chicks are already combining three different sound elements into calls. Elements and calls become longer and more modulated over time, though show limited similarity to the adult sounds and combination repertoire. Our findings provide empirical evidence that sound combinations are acquired slowly even in a classic non-vocal learner.

Interspecies communication about threats can shape animal communities, as many species produce alarm calls and also eavesdrop on those of others, creating information networks that cross ecological niches and taxonomic boundaries. Some species contribute disproportionately to these networks, as by being particularly vigilant or reliable, they act as keystone species that influence how others perceive danger. Predator encounters could also alter the soundscape more broadly, producing brief risk-related cues that reach many listeners. Yet the traits that make some species especially effective informants and how information about predators spread not only within animal groups but across entire communities remain poorly understood. Here, we used trained raptors to elicit alarm calls from birds and mammals in an Amazonian rainforest and used these calls to conduct 140 playback experiments across a 97-hectare plot. We found that alarm calls from canopy species under 100 grams elicited the strongest responses, particularly from other small canopy species, many of which propagated the information with their own alarm calls. At the same time, playbacks shifted the canopy soundscape, as other small species fell silent after hearing the alarm. These findings suggest that small canopy species play a central role in transmitting risk information, positioning the canopy as an acoustic “highway” for predator detection.

Learned acoustic signals in group-living animals serve diverse critical functions including locating mates, antipredator strategies and group coordination. This last is particularly relevant for social animals with fission-fusion dynamics, where vocal signatures of group and individual identity are critical as flocks associate and dissociate. Parrots are open-ended vocal learners with complex fission-fusion social structures, where vocalizations signal group identity and rapidly converge by social learning when groups come into contact. However, the influence of social hierarchy on the structure of learned signals remains underexplored. Here, we examined the relationship between social structure and vocal similarity in a captive colony of budgerigars (Melopsittacus undulatus). First, we filmed the colony to record behavioral interactions and construct an inter-individual social network. We then recorded males in an acoustically isolated chamber to obtain clean recordings of song and examined patterns of acoustic similarity both at the level of individual contact call-like notes (spectral similarity) and at the level of vocal sequences (syntactic similarity). Our results suggest that budgerigars exhibit a stable dominance hierarchy with females consistently outranking males, and that they exhibit individual signatures in both contact calls and the syntax of vocal sequences. Males that performed displays to each other tended to exhibit acoustic dissimilarity, whereas males exhibiting frequent aggressive interactions exhibited greater acoustic similarity. Finally, we found that higher-ranked males were more connected in an acoustic similarity network describing usage of different call subtypes, indicating that they shared more call types with others. Our study suggests an influence of social interactions on the structure of learned acoustic signals, which may be critical in mediating dominance interactions and signaling rank in these group-living birds.

Localizing a mate can be challenging and costly, especially in complex sensory environments. Mate localization can be facilitated by duetting, the coordinated exchange of signals between sexes. Duetting species include treehoppers, small insects in which stationary females reply to complex vibrational signals produced by searching males on plants. Both male and female treehoppers can adjust their signaling behavior to signals from the other sex, including changes in signal rate, duration, and amplitude. Here, we test whether variation in female signaling promotes adjustments in male signaling and searching behavior. First, we analyze male-female vibrational duets in the treehopper Guayaquila gracilicornis and quantify signal variation and mate searching behavior. Preliminary data shows large variation in female signal duration (0.4 – 2.5 sec), potentially in response to differences in male signaling behavior. Second, we use interactive playbacks to determine if changes in female signaling, possibly linked to their preference, can manipulate male signaling and searching behavior. Our study sheds light on how signal variation affects signaler-receiver dynamics in a severely understudied sensory modality, highlighting the active role females can play in sexual communication.

In the western Congo Basin rainforest, local people have long known that western lowland gorillas (Gorilla gorilla gorilla) chest beat not only sporadically during the day, but also regularly at night. This behavior has not been formally described nor explained in the scientific literature. Only mature adult male gorillas, or silverbacks, possess the laryngeal air sacs required to generate chest beats that can be heard over a kilometer away. We hypothesize that the temporal pattern and social and ecological correlates of chest beating may provide clues its evolutionary drivers. We placed 24 time-synchronized passive acoustic monitors over four different study areas each about 5 km2 in the dense tropical forest of the Lac Télé Community Reserve, Republic of Congo. We recorded 43,067 hours of audio data spanning 164 days and developed a deep learning model to recognize gorilla chest beats. Over 8,600 unique chest beats were identified. Of these, 89% were at night, with a peak between 19:00 and 23:00. By computing the location of each chest beat using time of arrival differences between acoustic monitors, we found evidence that silverbacks spaced over 500 meters apart hear one another’s chest beats and respond. Next-day ground truthing indicated that chest beats localized to both solitary and group-living silverbacks. Overall, these findings demonstrate that, despite its well-known role in close-range agonistic displays during interactions between groups and in within-group coordination, chest beating may have primarily evolved as a long-distance signal between social units. Chest beats are inherently costly to produce. They may be maintained by their influence on receivers, specifically in negotiating space use and navigating through complex social and ecological contexts. Whether chest beats contain information that is processed and retained by distant receivers, such as silverbacks’ identity, body size, age, or location, remains to be elucidated.

Visually guided animal behaviour is a vital factor in ecology and evolution. Recent decades have seen notable progress in understanding how neurophysiology, cognitive neuroscience, and psychology support visually guided animal behaviour. These advances have coincided with technological, computational, and theoretical developments, increasing our capacity to study animal vision in behavioural, ecological, and evolutionary research using both quantitative and qualitative methods. However, as we explore how ecological and perceptual contexts influence behavioural outcomes, evidence increasingly suggests that outside carefully controlled experiments, there is rarely a ‘one-size-fits-all’ approach for predicting the purpose and role of organismal colouration. Importantly, as our understanding of neurophysiological complexity and taxonomic differences deepens, theoretical models of animal vision and signalling are diversifying and being applied more broadly across various systems and ecological settings. Nevertheless, these tools often lack thorough empirical validation and are frequently used beyond their original aims and assumptions, prompting a discussion of current and future approaches to investigating animal colouration from the perspective of ecologically relevant observers. Here, I propose a conceptual framework to address some of these issues, drawing on recent advances in imaging, computing, and empirical research.

Finding water for hydration and breeding is one of the oldest wayfinding tasks for terrestrial vertebrates and remains a key navigational challenge for most amphibians today. However, the sensory and cognitive mechanisms that allow amphibians to navigate complex habitats and locate small bodies of water remain poorly understood. Neotropical poison frogs are terrestrial and lay their eggs on land, but parents must shuttle their tadpoles to small pools of water tens to hundreds of meters away.

Over the last decade, I have studied poison frog spatial movements and navigation in the wild using tracking and experimental manipulations of frogs and their breeding pools. We have demonstrated that poison frogs possess well-developed and flexible spatial memory and navigational abilities. Frogs can use odor to detect new breeding sites, but they memorize the exact locations after initial discovery. They rely on memory to flexibly and reliably choose direct routes to multiple small and distant goals, even after experimental translocations. Their ability to find home territories and breeding pools is disrupted only when frogs are released in unfamiliar areas.

Cross-species comparisons further reveal that navigational distances correlate with, but often exceed, the scale of species’ routine movements. These findings suggest two mutually non-exclusive hypotheses, neither of which has been empirically demonstrated in any animal. First, poison frogs may integrate and extrapolate directional information, such as sounds or smells, with exceptionally high accuracy, forming a high-precision navigational map (mosaic map sensu Wallraff, 1974). Second, they may form a large-scale cognitive map (sensu O’Keefe & Nadel, 1978) based on the spatial arrangement of landmarks in habitats lacking distant visual cues. I argue that the nature of poison frog navigational maps raises unresolved questions about amphibian cognition and the evolution of map-like representations in vertebrates.

Overimitation, the copying of causally irrelevant actions, is widespread in humans and contributes to the acquisition of social norms in children (Mackie et al., 2024). Although absent in non-human primates (Clay & Tennie, 2017), pet dogs have been shown to overimitate human demonstrators (Huber et al., 2018), especially their caregivers (Huber et al., 2020), suggesting a potential strong influence of previous experience and socialization. Here, we investigated whether overimitation also occurs in other populations than pet dogs, free-ranging dogs (FRDs). FRDs represent more than the 70% of the world’s dog population, they are not owned but they live alongside humans in complex environments, where they frequently observe and learn from humans’ actions (Cimarelli et al., 2023). As scavengers relying on human waste for their subsistence, FRDs may benefit from indiscriminate copying to maximize the chances of finding food; alternatively, they might copy humans selectively, thus overimitation may not be adaptive in their ecological niche. To test these hypotheses, we conducted a field overimitation experiment in a population of FRDs living in a touristic area in the south of Morocco. Using a randomized between-subjects design (N=140), dogs in the experimental condition observed a human demonstrator performing a typical overimitation sequence: an irrelevant action followed by a relevant one, each involving a different apparatus. FRDs showed no evidence of overimitation: none of the subjects tested with the overimitation sequence interacted with the irrelevant apparatus first. Unexpectedly, dogs did perform first the irrelevant action in the condition where the demonstrator presented the reverse sequence (relevant – irrelevant) and where both apparatuses contained food (N=5). This suggest that FRDs tend to approach the apparatus associated with the most recent action yet ultimately rely on direct food cues to guide their foraging decisions.

Cognition has generally been defined as an animals’ ability to receive, understand, and act on information received from the environment, and there has been extensive research linking cognitive ability and behaviour in vertebrates. In comparison, literature on invertebrate cognition is relatively limited. Furthermore, group size and social complexity may not be the most significant predictor of individual cognition, as workers are also subject to caste-specific selection pressures that can modulate cognitive development, meaning that individuals may be more influenced by the social complexity of their own castes as opposed to overall colony size.

Colonies were collected from across the Perth metropolitan area, and 50 ants from 20 colonies (total n=1000) were assayed.

In this experiment we used a bifurcated y-maze to perform associative learning assays using two odiferous compounds: Limonene and Octanal. Only one of the chemicals led to a food reward, and ants were required to learn this association in order to access the supplied food. The rewarded chemical, and rewarded side was randomised between trials. Ants were acclimated to the mazes 4 days prior to trial days, and food was withheld throughout this period.

Preliminary results show variation between individuals within the same colony, possibly attributed to R. metallica colonies consisting of several sister lines. Further analysis needs to be done between colonies as this is the first chapter of my PhD project.

From the ecological perspective of animal cognition, the capacity for sequence-learning by the cleaner wrasse Labroides dimidiatus is often attributed to its need to prioritize between two client types: visitors and residents, with access to either several cleaners or only one; respectively. Support for this view comes largely from a single field study, which helped establish the “biological-market” or “ephemeral-reward” task as a tool for studying the capacity of animals to learn contingencies across sequential events.

We present a second set of field data that allows a closer look at what happens when cleaners switch between clients, mid-interaction. At first glance, our findings match those reported previously: resident-to-visitor switches are more frequent than visitor-to-resident switches, as predicted by biological-market theory. However, our analyses suggest that mechanisms other than client prioritization may underlie this pattern.

First, the asymmetry in switch types does not differ qualitatively from the expected by chance, given client encounter rates. Second, the quantitative deviation from the null arises solely from fewer visitor-to-resident switches. Namely, cleaners are less likely than expected to leave a visitor for a resident, but not more likely to leave a resident for a visitor. Cleaners may thus seem to prioritize visitors, but only when engaging one.

Yet, our findings offer an alternative view whereby client behavior, rather than cleaner decision-making, produces the observed deviation. For instance, potential resident clients may avoid approaching cleaners already engaged with a visitor. In support of this view, we find that the probability of cleaners ending an interaction with a visitor, as a function of interaction duration, is unaffected by the presence of another waiting client.

Our findings do not challenge the success of cleaner wrasse in the biological-market task but do question the prevailing ecological explanation for that success

Heatwaves negatively impact behaviour with associated cognitive impairment in humans. A growing body of literature reports negative effects of heatwaves on cognition also in animals. A larger brain is known to generate enhanced cognitive abilities that may buffer against environmental changes and thereby potentially increase fitness in large-brained individuals. How a larger brain buffer against adverse effects on cognitive abilities induced by thermal stress, such as that experienced during heatwaves, remains unknown. We examined detour problem solving and working memory during an experimental heatwave in guppies artificially selected on brain size with matching differences in neuron number. Overall, detour problem solving was impaired among guppies during the heatwave, while working memory was unaffected. Large-brained guppies outperformed small-brained guppies in detour problem solving and working memory in both the heatwave and control temperature treatments. During the heatwave, large-brained guppies exhibited cognitive performance levels comparable to those of small-brained guppies under normal temperature conditions in the detour task. Our study thus suggests that small-brained individuals might have lower fitness also during heatwaves if increased temperature impair cognitive abilities required for survival and reproduction. Furthermore, our results open up the possibility that cognition-driven brain size evolution may have been influenced by abiotic factors.

Animals migrate to track trophic resources and suitable environmental conditions for reproduction. Despite the fact that migrating insects globally significantly outweigh migrating birds, they have received much less attention. To address this gap, and potential climate change impacts, we investigated migratory behaviour of the hummingbird hawkmoth (Macroglossum stellatarum) —a widespread and flagship Lepidoptera — across North Africa and Europe. As a polyvoltine species, its annual migration patterns are shaped by its ecological requirements for reproduction. Accordingly, we modeled monthly ecological suitability for reproduction across the study region to reconstruct this species’ potential migratory patterns throughout the year. Occurrences of reproduction sites were compiled from citizen science data –iNaturalist– and field surveys, and modeled using high resolution monthly climatic data within a biomod2 framework. The results revealed a clear pattern: optimal conditions for reproduction appear restricted to coastal areas of North Africa and Southern Europe in winter; shift northward up to Scandinavia during spring and early summer and return south in autumn. While widespread climatic suitability, represents the species’ potential range, actual distribution is constrained by other ecological factors such as host plants availability and land use. Because habitats suitable for M. stellatarum reproduction shift periodically, it is crucial for its conservation to protect not just single locations, but entire migratory pathways, with emphasis on winter refugia in North Africa and Southern Europe. Historical projections – using monthly climatic data from the previous century- revealed a slight recent northward shift in climatic suitability suggesting that climate change influences M. stellatarum migratory behaviour. These findings provide insights into insect migration and inform evidence-based conservation strategies for migratory insects under a changing climate.

In social species, individual fitness emerges from the interaction between reproductive behavior, social structure and environmental context. In highly social carnivores such as wolves (Canis lupus), reproduction is typically restricted to the dominant pair within family-based packs, while subordinate individuals contribute through cooperative behaviors. Understanding how social strategies translate into individual fitness across landscapes remains a central question in behavioral ecology, especially in recolonizing populations expanding across fragmented landscapes, where territory establishment may have long-term fitness consequences. We reconstructed multigenerational pedigrees of wolves in the Italian Alps thanks to a continuous genetic monitoring program conducted from 1998 to 2024 during the population’s natural expansion. From over 6,500 genetic samples, we identified 1,584 individuals and quantified individual genetic contributions to future generations as pedigree-based reproductive values. Reproductive values were estimated from kinship coefficients (f), as the probability that two alleles drawn from two individuals are identical by descent. For each reproductive individual, we quantified both direct reproduction and descendants' success through pairwise kinship. We then examined the spatial distribution of high-fitness individuals in relation to habitat characteristics, human presence and wolf density. Wolves with highest fitness and genetic contribution (n=10, with f>2%) were spatially clustered in the western Alps, within valleys corresponding to initial recolonization areas. Our results indicate that fitness during population expansion was unevenly distributed across space and closely linked to territory establishment. Early occupation of higher favorable areas can generate persistent fitness advantages across generations of social carnivores, highlighting long-term success of individual spatial decisions at the first stage of recolonization processes.

Migratory fishes are among the most threatened vertebrates worldwide, largely due to freshwater habitat fragmentation and the proliferation of anthropogenic barriers. When migration routes are blocked, many diadromous species become trapped in freshwater systems, unable to complete their life cycle by returning to the ocean to spawn. Under such constraints, individuals are likely to adopt behavioural strategies that differ fundamentally from those in free-flowing systems, with potential consequences for survival, growth, and ultimately population persistence. Yet, the fine-scale movement and habitat-use patterns of these “trapped migrants” in landlocked ecosystems remain almost entirely unknown. In this study, we use the Critically Endangered European eel (Anguilla anguilla) as a model species to investigate how migratory fishes adjust their behaviour in an enclosed drinking water reservoir. Using high-resolution acoustic telemetry, we tracked 185 tagged eels over two years inside an array of 151 receivers, yielding more than 10 million position records. Hidden Markov models were applied to classify individual movement trajectories into discrete behavioural states (e.g. resting, foraging, exploratory movement), and to quantify how state transitions and state-specific space use vary across diel (day–night) and seasonal scales, as well as among key reservoir habitats. By linking state-dependent behaviour to reservoir features that can be managed (e.g. drawdown regimes, shoreline complexity, locations of fish passage structures), this work aims to generate actionable guidance for improving the design and operation of dams for trapped migratory fishes. More broadly, our approach demonstrates how combining high-resolution telemetry with state-space modelling can reveal hidden behavioural strategies in human-modified freshwater ecosystems.

Mutualistic interactions between the Bluestreak Cleaner Wrasse (Labroides dimidiatus) and reef fish clients are fundamental to coral reef health, reducing parasite loads and influencing community structure. While the behavioral intricacies of these interactions are well-documented from a cleaner-centric perspective, the drivers governing client navigation and decision-making across broader spatial and temporal contexts remain understudied. We focus on client partner choice over extended periods within a reef hosting multiple potential cleaner partners, investigating the spatial selectivity of clients and the temporal stability of their cleaning-site preferences.

This study combines periodic habitat mapping with high-resolution acoustic telemetry to characterize the spatial ecology of cleaning in a ~30,000 m² reef area. We conducted continuous mapping of L. dimidiatus territories in the study site to establish a robust baseline of the site’s cleaning service distribution. Against this backdrop, we tracked client parrotfish across their home ranges using acoustic tags equipped with acceleration, inclination, and pressure sensors. This sensor integration revealed fine-scale movement, posture, and depth, allowing us to estimate behaviors such as feeding, roaming, sleeping, and visiting cleaning stations.

Our analysis indicates that clients exhibit consistent visitation patterns to specific cleaning stations within their home range. These preferences did not strictly correlate with proximity, suggesting that site selection likely involves factors beyond simple energy costs. These findings imply that clients navigate a complex landscape of partner options, extending the perspective of cleaning stations beyond static resources. Ultimately, this highlights the potential of integrating high-resolution telemetry with habitat data to better understand the spatial drivers of mutualistic interactions in the wild.

For small organisms, dispersal can be a matter of survival, as even crossing a few centimetres

of inhospitable terrain can be a formidable challenge. To overcome this, some species have evolved ingenious dispersal strategies, the most remarkable of which involves individuals coordinating into a larger superorganism, and traveling together. When dispersal becomes a collective act, it offers a uniquely powerful window into the understanding of collective decision-making. Individuals must coordinate to build functional structures, yet face unequal outcomes, as not all participants ultimately disperse. We investigated this balance by studying nematode collective dispersal. We found that nematodes build towers for attaching to by-passing vector for dispersal. Although individuals at the tower apex have a greater probability of successful dispersal, we found no corresponding difference in reproductive fitness across positions within the tower. This suggests that participation in tower formation may constitute a cooperative behaviour rather than a selfish scramble for advantageous positions. In a cross-strain comparison, however, we did not detect a link between towering propensity and known variation in sociality, measured as a tendency to aggregate under food presence. Our findings indicate that under environmental stress, nematodes readily form dispersal structures even when they are not naturally social, highlighting how ecological pressures can transiently induce collective organisation and cooperative action.

Through their lives, all animals exhibit a continuous series of behavioural states. Behaviour is a fundamental dynamic process, allowing animals to flexibly respond to variable environments. For a holistic understanding of behaviour, we must understand the underlying decision-making systems through which animals determine their actions instant-to-instant. The Behavioural Observatory is an ongoing venture to quantitatively study such decision-making systems across at least 500 individuals from fifty species. Using methods derived from physics and linguistics, I demonstrated the existence of a near-identical complex ('long-range') decision-making system across three very dissimilar species: hyenas, meerkats, and coatis. Under the Behavioural Observatory project, we have already discovered similar long-range decision-making systems in another eight mammal species.

The Behavioural Observatory Project aims to:

1. create an unsupervised machine learning method to automatically infer

behaviours in accelerometer data;

2. make available the inferred behavioural sequences of all 50+ species as

a first-of-its-kind dataset;

3. using this dataset, quantify and explore the underlying behavioural

decision-making systems for all individuals; and

4. use these decision-making systems as a proof-of-concept diagnostic tool for

animal welfare.

This project is one of the first massively cross-species study examining decision-making rules from long, continuous behavioural sequences, and it will grant novel insights into the principles upon which behaviour is structured. The dataset and open-source methods we publish will be very helpful to many future studies in behavioural ecology. The behaviour-based diagnostic tool we develop may prove instrumental in inexpensive monitoring of animal populations for conservation and welfare. The talk will conclude with a call-to-action to contribute data to this project.

09 09. Foraging

In most species, individuals select their mates based on specific preferred phenotypes or characteristics, also known as mate preference. These preferences can be genetically determined or learned, and identifying the genes underlying variation in mate preference has long been a goal of speciation and sexual selection research. Here, we use the butterfly Bicyclus anynana to functionally test a candidate gene involved in female visual mate preference. In B. anynana, approximately 75% of naïve females prefer males with two forewing spots over males with four forewing spots, while the remaining females exhibit the opposite preference. Juvenile hormone binding protein (JHBP) has been implicated as a promising candidate gene involved in this preference due to a genome-wide SNP association study, its role in development, and its expression in female adult brains during social interactions. To test the functional role of JHBP in mate preference, we used CRISPR Cas9-mediated mutagenesis to disrupt this gene and generate mutant individuals. Confirmed mutants were then bred with wild type (WT) individuals to establish mutant lines. We tested the mate preferences of mutant females using standard two-choice mate preference assays to determine whether disruption of JHBP altered female mating decisions relative to WT controls. We found that disrupting JHBP changes female mating outcomes which is consistent with a role for this gene in regulating innate visual mate preference. Together, this work provides direct functional evidence linking JHBP to female mate preference behavior in a butterfly.

16 16. Physiology and behaviour

Current research on intraspecific behavioral variation is deepening our understanding of the genetic architecture underlying behavioral traits. Despite the increasing sophistication of automated systems for behavioral monitoring and the decreasing costs of whole-genome sequencing (WGS), genomic studies of behavioral traits in wild populations remain scarce, and translating these genetic insights into evolutionary and neurobiological frameworks is a key next step. Here, by leveraging an ongoing invasion of horseshoe whip snakes (Hemorrhois hippocrepis) on the island of Ibiza (Spain), we assessed the genetic architecture of risk-taking behavior in their most common native prey, the Ibiza wall lizard (Podarcis pityusensis), a well-known example of island tameness. Using newly designed behavioral assays coupled with WGS data from over 300 individuals of this endangered lizard, we examined (1) shifts in risk-taking behavior throughout the snake invasion, (2) candidate loci associated with these changes—highlighting genes involved in neurodevelopment, fear-related behaviors, spatial cognition, and hippocampal calcium metabolism—and (3) signatures of selection acting on these genes in response to the invasion. Our study provides valuable insights into the genetic underpinnings of risk-taking behavior in wild populations and into how island endemic species can adapt to rapid shifts in predation regime.

Navigation and migration are remarkable abilities that have fascinated humans since the dawn of history. How do night migratory passerines manage to find their way along their inherited migratory routes remains a mystery. The mechanisms that guide migratory navigation are complex and are shaped by both genetic and environmental factors. Recently, the combination of molecular technologies and advanced tracking methods has opened new possibilities for unravelling cryptic parts of these mechanisms. In this study, we integrate advanced tracking technologies (the ATLAS system) with genetic methods to examine the genes that correlate with spring migration azimuth in the Eurasian Blackcap (Sylvia atricapilla), a key model species in migration research. The research site in the Hula Valley allows high-resolution integration of these two approaches. During spring migration, when this species migrates northward to its breeding grounds, the Hula valley serves as a land funnel having a variation of migration azimuth in this species. Correlating the variation azimuth with mutations with 67 suspected migration related genes revealed eight genes with genetic variants that correlate with the differences in migratory direction and significantly differ between the two main migration azimuth groups. The majority of these genes are biological-clock related genes such as CSNK1D, EYA3 and CRY1. Taken together we place 8 target genes and mutation regions within them, as potential migration azimuth regulating genes. Being a correlation-based study, these results do not show causality but rather highlight potential migration-azimuth related genes.

Inbreeding depression is a persistent problem in laboratory populations maintained over multiple generations, potentially reducing reproductive fitness and even compromising behavioral studies. Although pedigree information permits kinship estimation, identifying low-relatedness mating pairs becomes increasingly impractical as populations grow. We developed a kinship-based algorithm to optimize mate assignment and evaluated its performance against conventional manual pairing in the burying beetle Nicrophorus vespilloides.

Two parallel breeding lines were maintained across multiple generations: one using semi-random manual pairing and one using algorithm-optimized pairings. For each generation we quantified mean kinship coefficients and reproductive success measured as offspring survival from larvae to adulthood.

Algorithm-managed lines maintained significantly lower mean kinship coefficients than manually paired lines. Additionally, the algorithm line exhibited 43.6% fewer complete reproductive failures. Across both lines, higher kinship was negatively associated with offspring survival, and the manually paired line showed a progressive increase in kinship over generations.

Our results show that using computer-assisted pairing based on relatedness can successfully reduce the build-up of inbreeding in laboratory populations, without causing measurable losses in fitness. We also propose that the average relatedness across the whole population can serve as a simple numerical measure of how well genetic diversity is being maintained, allowing researchers to routinely monitor the genetic quality of breeding lines in behavioral ecology studies.

Social behavior is often driven by competition, both within and between species. In the Asian burying beetle Nicrophorus nepalensis, interspecific competition for breeding resources with blowflies favors cooperative breeding behavior. Beetles cooperate more at lower elevations, where temperatures and blowfly pressure are higher. At the lowest elevations, however, blowfly pressure is so great that cooperative breeding is no longer successful. Instead, low-elevation populations in Taiwan switch from year-round to seasonal breeding in winter when blowfly pressure is lowest. To explore the genetic architecture of this locally-adapted polymorphism in reproductive photoperiodism, we generated two chromosome‑level reference genomes, re-sequenced nearly 200 genomes from across Asia, performed genetic crosses with populations collected along an elevational gradient, and examined developmental gene expression in beetles reared on different photoperiods. We identified a ~13 Mb inversion that houses a photoperiodic locus acting as a binary molecular switch between year‑round and seasonal breeding. This ancient inversion arose in China nearly 3 million years ago, arriving in Taiwan only in the last 600,000 years in one of multiple colonization events. Genome wide association studies (GWAS), genetic crosses, and transcriptomic analysis of genes and gene networks suggest the photoperiodic locus is dominant with respect to the inversion. It acts as a supergene and contains five tightly linked genes: an odorant-binding protein that likely enhances mate location during permissive seasons, two structural proteins known to enforce diapause, and two master regulatory switches that appear to regulate the pathway according to photoperiod. Ultimately, this work illustrates how standing structural variation enables rapid local adaptation under high gene flow via a supergene‑like module that couples environmental cues to reproductive timing via shifts in competitor-driven social behavior.

While research has addressed how the parasitoid infiltrates the colony to find its host, less attention has been given to its developmental phase. In this study, we investigated whether I. eumerus, like its butterfly host, manipulates ant behaviour to induce workers to care for the pupal case in which it develops. We examined whether P. alcon parasitised pupae produce vibroacoustic signals and whether these emissions resemble the manipulative signals of unparasitised pupae. Finally, we assessed whether parasitised pupae elicit ant attention and care using behavioural assays involving direct exposure of workers to alive pupae and acoustic playback experiments.

We discovered that I. eumerus pupae emit two distinct types of vibroacoustic signals, one of which closely overlaps with the signals produced by P. alcon pupae in both intensity and frequency parameters. However, in our behavioural assays, I. eumerus parasitised pupae elicited little ant attention compared with the strong responses induced by P. alcon unparasitised pupae. Our results indicate that, although I. eumerus can produce butterfly-like vibroacoustic signals, this acoustic similarity does not translate into effective manipulation of ant behaviour under the tested conditions. If functional, vibroacoustic mimicry in I. eumerus may be restricted to specific developmental stages and/or social contexts, highlighting the limits of signal exploitation in this multi-layered parasitic system.

Fungus-growing termites are canonical examples of the evolution of agriculture in insect societies. They grow a fungus Termitomyces sp. for food on spongy structures known as fungus comb. However, just like human agricultural fields, these fungal crops are also prone to invasion by other weedy fungi. Pseudoxylaria is the most dominant weed in termite fungal gardens. Since termites cannot subsist on any fungi other than Termitomyces, it is essential for termites to detect and suppress any weedy fungi. The precise mechanisms by which termites prevent Pseudoxylaria remains unknown. Previous studies suggest the role of symbiotic fungistatic microbes in bringing about weed control. However, how termites employ these microbes to suppress the fungal-weeds, without affecting the fungal-cultivar, remains unknown. Here by using dual choice assays, we show that the fungus-farming termite, Odontotermes obesus, uses specific behaviors to remove, isolate and suppress the growth of the fungal weed Pseudoxylaria, by primarily encasing them with soil boluses containing fungistatic microbes. These behaviors efficiently suppress the weed without affecting the crop. This integration of specific behaviors with termite-derived microbes appears to be the proximate mechanism of how microbes are topically used by termites to confine the weed while keeping the crop unaffected.

Invasive species often possess traits that promote their spread, such as high fecundity, rapid development, and strong dispersal ability. In some cases, they may also be less susceptible to natural enemies such as predators and parasites. The brown widow spider Latrodectus geometricus (Koch) is a highly invasive species worldwide. One of its main natural enemies, shared with other widow spiders, is the parasitoid wasp Philolema latrodecti (Fullaway), which lays its eggs inside spider egg sacs; the wasp larvae consume the spider eggs, pupate within the sac, and emerge as adults. We show that L. geometricus is less susceptible to parasitism by P. latrodecti than a native species, the white widow spider L. pallidus, under both field and laboratory conditions. We hypothesized that this difference is due to superior egg-sac defenses by the invasive spider. Through manipulative experiments, we found that the silk spikes and loose threads covering L. geometricus egg sacs disrupt wasp oviposition, and that L. geometricus females defend their egg sacs more actively against parasitoids than do L. pallidus females. Moreover, L. geometricus females increased the density of silk spikes on subsequent egg sacs following parasitoid exposure, indicating an induced defensive response. We suggest that enhanced defenses against parasitism may have contributed to the invasion success of L. geometricus and may similarly facilitate invasions by other species.

Some lineages of avian obligate brood parasites circumvent detection in the parasitized clutch by mimicking the eggshell coloration of their hosts species. Egg color mimicry is mediated by two main pigments' deposition into the shell's surface or matrix (protoporphyrin IX and biliverdin), respectively. Here I evaluated whether published patterns of the type of pigment-matching by the parasite are dependent on the nesting behaviors (nest type construction and incubation) of its host species. The data suggest that eggshell pigment matching can be poorer in enclosed than in open cup nests and in hosts with both rather than a sole sex of parents incubating. These results imply a role for host perceptual accuracy to play a role in how eggshell coloration is matched by mimetic species of obligate avian brood parasites.

The reciprocal relationship between the gut microbiome and the host biology is acknowledged in domestic animals and humans, but rarely accounted for in wildlife behavioral ecology and conservation. The importance of the microbiome in wildlife is increasingly recognized, with recent studies linking the microbiome to host movement patterns. In parallel, the emergence of antibiotic-resistant bacteria (ARB) in wildlife microbiomes is increasing, yet the exposure mechanisms and effects on the host remain unclear. We examined the relationship between the spatial behavior and demography and the presence of ARB in the microbiome of griffon vultures (Gyps fulvus) in Israel. These locally endangered scavengers are provisioned by authorities with safe supplementary livestock carcasses. We hypothesized that the individual proximity to urban areas and foraging habits would affect ARB positivity, and investigated whether ARB positivity affects host movement. We sampled the microbiome of GPS-tracked wild vultures using choanal and cloacal swabs, and performed β-Lactam antibiotic resistance tests (ESBL). The resistance results were compared to the individual demography, home range and daily movement indices. We found that the Israeli northern sub-population had significantly higher ARB prevalence (61%) than the southern sub-population (31%). However, ARB positivity did not correlate with host home range size, daily movement, or feeding station usage. These results indicate that the vulture population in Israel is exposed to antibiotic residues or ARB, and that the habitat area affects exposure, possibly in accordance with proximity to urban areas. Better understanding these dynamics may support refining local conservation practices, especially with regard to providing safe food for vultures, as well as expand our understanding of the interactions between the microbiome and movement behavior in wildlife and the role of ARB in this interplay.

Avian brood parasites, such as cuckoos, exploit parental care by laying their eggs in the nests of other birds. In response, hosts have evolved adaptations to prevent parasitism such as the recognition and rejection of foreign eggs and, in turn, parasites have evolved mimetic eggs to avoid detection. Past research has typically examined pairwise relationships between a single brood parasite and host, with the interactions between the two species described as a coevolutionary arms-race. Such truly pairwise systems are, however, rare in nature and multispecies interactions between multiple species of brood parasites and hosts are the global norm, suggesting that a multispecies framework may better explain the evolution of egg recognition and rejection behaviours. To investigate the thresholds of egg rejection and acceptance of hosts which are subject to multispecies interactions, we created realistic model eggs based on the Horsfield’s Bronze-cuckoo spanning six phenotypes which encompassed the visual and tactile variation of the 167 eggs held in the Australian National Wildlife Collection. Model eggs were placed in the nests of three fairywren species that occur at our field site in eastern Australia—the region which is the global epicentre of complex brood parasite–host systems—where they occur in sympatry with multiple cuckoo species which parasitise them including the Horsfield’s Bronze-cuckoo. We found egg rejection rates were lower than in other brood parasite–host systems around the world and found no significant difference in rejection rates between egg phenotypes. Our findings suggest that the evolutionary trajectories of egg-stage defences have been shaped in different ways by multispecies interactions highlighting the importance of alternative frameworks for studying the evolution of behaviour in complex species communities.

07 07. Behavioural plasticity

In sexually reproducing species, sexual selection is often critical for individual fitness. To select a mate, individuals can use information on potential partners provided by honest signals reflecting their quality, such as plumage traits in birds. Yet, potential partners often display several signals that may convey different information, and may also depend on the chooser’s phenotype; the resulting information transfer can thus frequently be more complex than often considered. In particular, birds can display plumage colors resulting from both pigments (produced by the organism such as melanin or acquired from the diet such as carotenoids) and the feather barbs’ microstructure, with different associated costs underlying signals’ honesty. The information conveyed by these different signals could be either redundant, complementary or conflicting, making the interpretation of the use of single signals for mate choice difficult in a context of multi-signalling. We investigated the potential complementary, conflicting or redundant role of two plumage traits and their potential use as multi-signals for mutual mate selection in a wild population of White-throated dippers (Cinclus cinclus). Males and females both display a ventral white (structural) patch and rufus (pigmentary) belt during courtship. We show how these two plumage traits reflect individual quality through their links with reproductive variables and lifetime reproductive success, depending on individual factors such as age and sex, and explore the differences in information conveyed between females and males’ signals. We then investigate how these two signals may be used for mate choice in each sex based on assortative mating and differences between breeding and non-breeding birds. Our study provides keys to unravel the relative role of different signals with different mechanisms of honesty for mate choice decisions and conclude about the potential interaction or similarity of the information they convey.

Males typically face substantial costs when competing for access to females. These costs include the risk of injury from fighting and reduced paternity when more than one male mates with a female. Theoretically, males should therefore avoid chasing the same female as their rivals. However, male–male associations, where males remain close to each other while simultaneously attempting to mate with the same female, are widespread in some species. One explanation is that male aggregations may enhance courtship success, but this cannot explain male-male associations in species without courtship, such as mosquitofish. Very few studies have explored the mechanisms or potential benefits of male–male association in these species. In our study, we first tested whether male mosquitofish prefer to associate with each other when pursuing females . After confirming that they do, we then ran two choice experiments to investigate four possible social mechanisms to explain male–male associations: (1) mate-choice copying, (2) female behavioural changes, (3) conspecific cueing, and (4) shoaling. Finally, we measured male mating behaviours (e.g. number of mating attempts) when a focal male was placed with a female either with or without a rival present to see if the focal male benefited. In the two-choice experiments males showed a significant preference for shoaling, suggesting that mating-related benefits are not the primary driver of male–male association. Finally, males made fewer mating attempts and spent less time following a female when a rival was present, indicating that male–male association imposed costs rather than benefits on mating behaviour. Overall, our findings suggest that this behaviour is more likely driven by the general benefits of shoaling with conspecifics rather than by advantages related to mating.

Sperm operate in a complex biophysical environment, dominated by the viscous environment of the surrounding fluids through which they swim. Minor changes in fluid viscosity can profound impacts on sperm performance (e.g. forward progression, swimming speed) and in particular have the potential to act as a selecting force to prevent poorer quality sperm reaching the ova. We set out to test whether sperm performance of male Tenebrio molitor differed across the life course (newly eclosed, peak reproductive age, late-life senescence) and whether differences in sperm performance were magnified when tested in fluids of differing viscosity. Our results show a classic early life improvement in sperm performance measures, with late-life declines in sperm performance. Moreover, when tested in higher viscosity media, the sperm of older males showed the greatest reduction in swimming performance with slowest speeds and reduced forward progression. We show that a relatively simple change by the female to the sperm competition arena, is an effective strategy to reduce fertilisation success of poor quality sperm. This again emphasises the critical role of female cryptic female choice in control of reproduction.

According to optimal inbreeding theory, natural selection favors an intermediate level of inbreeding in which the inclusive fitness benefits of mating with relatives outweigh the costs of inbreeding depression. Despite strong theoretical support, the proximate mechanisms underlying this balance have remained unclear. The biparental cichlid fish Pelvicachromis taeniatus is an ideal model system to investigate this question because it shows strong kin-mating preferences, and inbreeding can be adaptive due to improved parental cooperation during brood care.

To test whether kin preference depends on an individual’s own level of inbreeding, we compared highly inbred fish, outbred fish, and outbred crosses of inbred lines. Genomic analyses confirmed lower heterozygosity in inbred individuals, while outbred fish and outbred crosses showed similar genome-wide heterozygosity. Mate-choice experiments revealed that highly inbred individuals avoided mating with relatives and instead preferred unrelated mates, indicating a shift toward outbreeding when inbreeding levels are high. In contrast, outbred individuals retained strong preferences for kin.

These results support the “inbreeding-dependent kin-choice” hypothesis, demonstrating that mating preferences change according to an individual’s inbreeding level. Kin recognition itself was unaffected by inbreeding; instead, preferences shifted flexibly between kin preference and kin avoidance depending on one’s own or a potential mate’s inbreeding level or associated phenotypic quality. This dynamic adjustment provides a mechanistic explanation for how optimal levels of inbreeding are achieved in this species.

Selective Pressures on mating strategies can act differently on each sex depending on social and environmental factors. In bulb mites (Rhizoglyphus echinopus), males exhibit two morphs: a weaponized fighter morph, and a passive scrambler morph. While it is assumed that the weaponry of fighter males is used to monopolize females by killing rivals, this has never been tested in a natural social context with multiple, diverse groups of males. I investigated if fighter and scrambler morphs gain any advantages in different social contexts and how these social contexts affect male and female fitness. I found that fighting behaviours had negative effects on male fitness, but positive effects on female fecundity. On the contrary, female survival was negatively affected by fighting behaviour. I argue that an increase in male density increases intrasexual aggression among males which allows opportunistic males to mate while competing males are distracted.

Evolutionary changes in sexual traits occur when the selective forces maintaining them weaken or disappear. It is generally accepted that nuptial gifts may have originated through sensory exploitation, as males that offer a food gift during courtship exploit female foraging motivation. In such a scenario, any deviation from the female’s original selected trait (food gifts) will decrease her fitness and can lead to changes in her preferences favouring counteradaptations. This seems to be the case in the spider genus Trechaleoides, which is composed of two species that are morphologically identical but differ strongly in their mating systems. While T. keyserlingi is polyandrous -with males offering nuptial gifts and females exhibiting very low frequencies of precopulatory sexual cannibalism- T. biocellata is practically monogamous, males lack nuptial gifts and females are extreme cannibals. Here, I aim to present a sequence of studies to discuss possible evolutionary pathways for this divergence. First, I will show behavioural experiments demonstrating the lack of female preference for the nuptial gift in both species, as well as the ineffectiveness of the gift in protecting the male in the cannibalistic species. Second, I will present results from comparative transcriptomics showing that genetic diversity is relatively lower in the cannibalistic species. Third, considering that sexual cannibalism may arise from females’ energetic requirements, I will discuss its potential link to their standard metabolic rate and therefore, its determination at the genetic level, revisiting the well-known “Aggressive Spillover” hypothesis. Overall, this genus helps to illustrate co-evolutionary changes in male and female traits and their possible effects at the population level; while also exploring unsolved puzzles, such as sexual cannibalism, from new evidence and perspectives.

In post-copulatory sexual selection (PCSS), sperm competition and female sperm control (e.g., cryptic female choice) have often been considered independent processes. However, because sperm competition occurs on female reproductive traits, female actions can influence its dynamics. Fertilization success, which determines selection pressure, may thus be shaped by the interaction between sperm competition and female sperm control. Nevertheless, this interaction remains poorly understood, as female reproductive traits are internal and difficult to observe in many animals.

The Japanese pygmy squid, Idiosepius paradoxus, provides a rare opportunity to directly investigate interactions between PCSS components. Males attach spermatangia externally to the female body, and females remove them after mating, allowing direct observation of changes in sperm numbers that determine the outcome of sperm competition. Using this feature, we observed matings in which a female mated sequentially with multiple males in an aquarium.

We found that the first male’s spermatangia were removed not only immediately after mating but also following subsequent matings by later males. This occurs because spermatangia from the first male that remained after the initial removal mixed with spermatangia from later males and were then removed together, leading to additional sperm removal of the first male’s sperm. Consequently, the first male was at a disadvantage in sperm competition. Field observations further confirmed that females mate sequentially with multiple males, indicating that such additional sperm removal also occurs under natural conditions. Taken together, these results demonstrate that female-mediated sperm removal can repeatedly reshape the outcome of sperm competition, revealing an important but previously overlooked aspect of PCSS. Our findings underscore the need to explicitly consider female sperm control when interpreting patterns of sperm competition.

Sexual conflict arises when the reproductive interest of the sexes diverges. Sexual coercion is a manifestation of sexual conflict when a male uses aggression to coerce a female into mating with him. Coercion can be direct via sexual harassment or work longer-term via male intimidation of the female. Here, we investigated both aspects of sexual coercion along with alternative hypotheses, i.e. the aggressive-male-phenotype hypothesis and the social bonding hypothesis, which both include elements of female choice. We studied wild Assamese macaques in a long-term project in Thailand. The species is characterized by a promiscuous mating system, concealed female fertility, low male mating and reproductive skew, low aggression rates, and differentiated male-female affiliative relationships, i.e. social bonds. Using behavioral data collected over a five-year period and across three multi-male multi-female groups (>7500 focal observation hours), we found no effect of intimidation (aggression in the three months prior to the mating event) as one form of sexual coercion and also not of a male’s general aggressiveness (aggressive-male phenotype) on male mating success. Instead, male mating success was independently predicted by male sexual harassment of females (female-directed aggression on the day of copulation) and dyadic male-female bond strength (affiliative Elo score), consistent with both the sexual coercion and social bonding hypotheses for male mating success. Thus, male-female dyads in this promiscuous system vary in whether sexual strategies converge or are in conflict.

The occurrence of males can result in both costs and benefits to a population’s fitness. On the one hand, there is the well-known “two-fold” cost of producing males, who are energetically costly to produce yet typically contribute negligibly to resource investment, leading to slower population growth (all else being equal) relative to a population of parthenogenic females. On the other hand, sexual selection in males can result in more efficient purifying selection against deleterious mutations, which yields an evolutionary increase in population growth by elevating female survival and/or fertility. The net consequences these costs and benefits have been worked out for obligately sexual species, yet it remains unclear how they might balance out in facultatively sexual taxa, which engage in both sexual and asexual reproduction and, therefore, express the costs and benefits of producing males to different degrees relative to obligately sexual taxa. Using mathematical model, we assessed how demographic costs of producing males and benefits of enhanced purifying selection affect genome-wide fitness in a facultative asexual population. We show that the elimination of male production during asexual generations reduces both the two-fold cost of sex and benefits of stronger purifying selection through males, yet the effect of the former is stronger than that of the latter, which allows facultative sexual systems to more easily overcome the “two-fold” cost of male production and outperform complete asexuality. Our model extends the theory for the evolution of sex and of sexual dimorphism and has implications for prevalence of facultative sexual systems in nature.

Despite being at the heart of reproduction, the drivers in variation of copulation duration are not poorly understood. I present a comparative project, using data on the average duration of copulation duration across 200+ bird species. I tested four hypotheses for the drivers of copulation:

1) Predation Risk Hypothesis: An individual is vulnerable to predation when having sex. Vulnerability to predation was paramertised in four ways: as mass, assuming that smaller species were more vulnerable than larger species, colouration, assuming that brighter species were more likely to be observed having sex than duller species, by habitat openess, with the assumption that species living in more open habitats would have fewer places to safely hide and have sex without being seen by predators, and by nest openess, with the assumption that species which have more closed nests would be likelier to have longer copulation duration.We did not find support for this hypothesis.

2) Sperm Competition Hypothesis: We tested whether copulation duration was a product of sperm competition, with species with a stronger sperm competition engaging in longer sex, to deny other males an opportunity to have sex with the female. We used mating system as our proxy for sperm competition. We did not find support for this hypothesis.

3) Sociality Hypothesis: We tested whether longer sex might be due to species enjoying it. Our assumption is that sex for pleasure, including purposeful elongation of the sex act, would be likelier in species which are smarter, and which are more social. We assumed that social system would influence this since longer sex, and sex for pleasure, would fall under socio-sexual behaviours. We found mixed support for this hypothesis.

4) Energetic Cost Hypothesis: Sex can be an energetically costly behaviour. We tested whether this cost limits the duration of sex, using trophic level and main food source as proxies for energetic cost. We found mixed support for this hypothesis

Evolutionary conflicts of interest between the sexes are ubiquitous. In polygamous species, adaptations have evolved in males that reduce the risk of sperm competition. These adaptations can affect the functional morphology of male genitalia and their interactions with female genitalia during mating, resulting in harmful adaptations that hinder females from remating with subsequent males.
In the orb-weaving spider Larinioides cornutus, females were found with and without damage to their external genitalia (epigyne) in the field, suggesting that males may remove the female’s genital coupling structure (scapus) during mating, as previously documented in two other orb-weaving spiders. First, we investigated the mechanism of female genital damage in L. cornutus using staged mating experiments, cryo-fixation of mating pairs, and high-resolution imaging (SEM and micro-computed tomography). Indeed, males are responsible for damaging the female epigyne by a mechanism that is unknown in the other investigated species. Males remove the scapus and a substantial part of its base through an intriguing interaction between several sclerites and a novel piercing structure. Second, we explored the consequences of genital damage by staging mating trials with females with damaged epigynes. Re-matings were not successful, which was not due to mechanical coupling problems, as previously found for another orb-weaving spider, but due to the reduced receptivity of females after mating. We discuss the possibility of manipulative substances in the ejaculate that reduce female receptivity, and whether the maintenance of genital damage is expected in this species. This study contributes to our understanding of the mechanisms of harmful mating in arthropods and highlights the repeated independent evolution of male strategies that reduce sperm competition risk by removing parts of the female genitalia.

Interspecific information flow can enhance individual’s fitness by shaping animals’ responses appropriately to changing environmental conditions. Yet, it is unclear how the species diversity of information sources affects information flow in the community. We addressed this question experimentally by examining how bird communities respond to mobbing calls of species at varying richness levels. At Thousand Island Lake, China, we conducted two playback experiments (413 trials, in total), manipulating the number of calling species (1, 2, 4, and 8 species), and measured mobbing responses as the number of participating species and individuals in the mob, call rate, latency, and frequency range. In the first experiment, the number of mobbing calls was kept constant across treatments, while in the latter, the number of calls increased with the addition of species. Generalised additive models found species richness to increase the number of responding species and individuals in both experiments. This relationship remained positive for heterospecific responses alone, as well. ANOVA analyses comparing responses to each of the 8 species’ 1-species treatment, with corresponding 4-species treatments, with and without the focal species, showed that heterospecific responses in both experiments were mostly driven by the number of species, and not the species identity. We expect other metrics, call rate, latency and frequency range, will show similar results that responses will not be specific to any one species. This would indicate that complementary differences among species in the information they provide serves to increase mobbing response at the community level.

Vocal signalling plays a fundamental role in maintaining social interactions in group-living animals, as it allows individuals to exchange information efficiently and, in many cases, to be individually recognized. In corvids, acoustic signals are a primary communication channel, yet – despite their prominence in cognitive studies - little is known about the development of their rich vocal repertoires and how they are shaped by individual and social factors. Here, we investigate when vocal identity (i.e. ‘voices’, idiosyncratic vocal features that signal vocal identity irrespective of call type), distinct call types and contextual vocal usage develop.

Using high-quality recordings of hand-raised carrion crows (Corvus corone) over multiple developmental stages ranging from nestlings to subadults, our analyses show that vocal individuality is already detectable at an early developmental stage. It is encoded by a combination of acoustic features that remain stable as birds mature. As development progressed, vocal differences between individuals became more pronounced, although the direction and magnitude of change depended on behavioural context. In parallel, call usage shifted markedly over time, reflecting the transition from parental dependence to social integration.

Our findings highlight that corvid vocal communication is shaped by both ontogenetic processes and social environment. By linking early vocal development with later social signalling, this work advances our understanding of how vocal individuality and social communication co-develop in a highly social species.

Animals widely use acoustic communication to transmit information, from individual identity to mating status. Another crucial use of acoustic communication is predator defence. During mobbing, prey collectively harass a predator, and individuals may signal not only the predator’s presence but also its type and proximity, allowing receivers to adjust their responses accordingly. Here, we experimentally examined whether the mobbing calls of the sociable weaver (Philetairus socius), a colonial cooperative passerine, encode information about the type of predator faced. Using a combination of model presentations and playbacks, we examined the weavers’ responses to two key predators, snakes and pygmy falcons (Polihierax semitorquatus). Additionally, we compared them with reptile and avian controls. Predator treatments elicited significantly stronger responses than controls (e.g., higher call rate). Although one call type was common across responses to both threats, each predator also elicited a distinct call type. These findings support the growing evidence that animal calls can convey information about both the presence and identity of predators.

Passive acoustic monitoring (PAM) is increasingly used to study acoustically active animals. In addition to being non-invasive, it enables researchers to monitor species that are difficult to observe directly, such as nocturnal or wide-ranging species. PAM can address diverse ecological questions like abundance, social dynamics, intraspecific and interspecific interactions, and the effects of anthropogenic disturbances. Recent advances in signal-processing algorithms have also introduced tools that help distinguish among species, sexes, age classes, and even individuals.

One of the most distinctive vocalisations in large carnivores is the loud, low-frequency roar of lions (Panthera leo). Lions vocalise to transmit various signals, such as advertisement of territory, mating, and group size. Vocalization studies on African lions have found variation in the vocal signals across behavioural contexts, between sexes, and individuals. However, the vocal behaviour of Asiatic lions, an isolated subpopulation found only in Gujarat, India, remains understudied.

We investigated the information encoded in Asiatic lion roars and identified the acoustic features carrying this information. We analysed roars from 11 semi-captive lions (six males, five females) recorded at two sites in Gujarat. We quantified acoustic parameters in various structures of the roars, including the bouts, within-bout roars, and within-roar frequency bands, and used principal component analysis to explore clustering patterns.

While the extent of clustering by sex and by individual varied across the structural levels and components of the roars, we found clear and consistent separation of roars by site. This provides preliminary indication of geographic variation in Asiatic lion roars, similar to patterns reported for African lions. Such vocal “fingerprints” may reflect the habitat differences in which they have evolved and the importance of the geographic origin as a marker of individual identity in lions.

Animals living in social groups with fission-fusion dynamics can benefit from sociality by cooperating and forming associations with groupmates, but are able to separate when the costs of grouping become too high. This poses a unique challenge, since reunions with other individuals or groups require individuals to assess the social situation they are entering and to clarify their intent in order to reduce the chance of aggression. Many species use specific signals, such as body postures or vocalizations, to signal intent and reduce conflict when approaching others after separation. Spotted hyenas (Crocuta crocuta) live in large hierarchical clans, but spend most of their time alone or in small subgroups with changing compositions. They exhibit a complex vocal repertoire that facilitates cooperation and social interactions, including the low frequency “groan” calls that are hypothesized to signal benign intent and reduce the chance of aggression. Groans are challenging to study due to their low amplitude and low frequency, and the resulting difficulty in determining which individual is calling. To assess the role of groans in regulating conflict during reunions, we collected movement, accelerometer and audio data by deploying tracking collars on a clan of 19 hyenas in their natural habitat, providing a unique opportunity to study these subtle vocalizations with a level of detail that has not been possible with conventional field observation methods. These data allow us to assess individual roles in approach vocal exchanges, investigate possible graded signaling functions in groans and relate them to the outcomes of approach interactions. By elucidating the function of the groan we aim to reveal how vocal signals help spotted hyenas negotiate conflict during encounters and maintain their cooperative society.

The study of temporal structures in animal vocalizations revealed the presence of shared rhythmic structures across various human and non-human primates: adjacent intervals often cluster around small-integer ratios, producing rhythmic categories. However, the primary focus of studies conducted so far was the rhythmic structure at the individual level, but what is the rhythmic structure that emerges from two individuals singing together? Siamangs are singing primates producing units through their resonant oral cavity and inflatable vocal sac. The presence of two different mechanisms for vocal production makes the siamang an interesting model for studying rhythmicity at the individual level. Moreover, siamangs also create long and complex choruses and duets, allowing the study of rhythmic patterns emerging at the group level. We analysed duets produced by six different pairs of siamangs from different zoos, for a total of twelve individuals (six females). We investigated temporal organisation at both the individual and group levels. Specifically, we examined rhythmic categories emerging from small-integer ratios between adjacent intervals. Our analyses reveal a strong tendency toward isochrony, in which adjacent intervals have the same duration (1:1 rhythmic category), at both the individual and group level. Overall, the rhythmic structure observed at the group level mirrors that found at the individual level, pointing to a fundamental role of isochrony in both siamang vocal production and coordination.

Playback experiments are a cornerstone of behavioral ecology, yet most rely solely on acoustic stimuli. We tested whether adding a visual cue, a taxidermic mount, modifies territorial responses in two passerines: the chaffinch (Fringilla coelebs) and the chiffchaff (Phylloscopus collybita). We conducted 40 experiments per species using playback tracks standardized to each species’ mean song parameters, including typical song rate and amplitude. Behavioral responses measured included song and call rates, latency to first song, number of flights, and approach/attack variables, and were summarized using Principal Component Analysis.

The presence of a taxidermic mount significantly altered territorial behavior. In chaffinches, the mount shifted responses toward greater caution and call-based signaling, with longer latency and reduced song output compared to playback alone, while flights were more frequent without the mount, suggesting active searching in the absence of a visual intruder. In contrast, the mount triggered a strong shift toward close approach and physical aggression in chiffchaffs, with more time spent near the mount and more frequent, longer attacks, while song output declined. Vocal activity during playback remained similar across treatments, indicating that aggression dominated the response when the mount was present, whereas in its absence, males relied primarily on song signaling.

These findings reveal species-specific defense strategies: chaffinches primarily adjust vocal signaling, whereas chiffchaffs escalate to physical confrontation when visual cues are present. Our results highlight that multimodal playback designs are essential for capturing the full spectrum of territorial behavior, as acoustic-only experiments risk underestimating aggression and context-dependent responses. This research was funded by the National Science Center, Poland (project number 2022/47/D/NZ8/00565).

For any acoustic signal to convey information, it must first be detected. In human communication, introductory phrases such as “listen” or “look” serve to recruit attention and prepare receivers for an upcoming message. Many animals have been suggested to use similar tactics, employing alerting acoustic components to orient receivers or enhance signal detectability. However, despite these widespread observations, their alerting functionality and its impact on communication have rarely been systematically examined. As a result, the broader phenomenon remains poorly defined, and there is no unified framework for identifying and evaluating such alerting and attention-modulating components.

We present a scalable, modular framework for identifying acoustic alerting components based on three axes: (1) physical propagation properties of the signal, (2) flexible usage by signallers, and (3) impact on receiver responsiveness. Because each axis can be evaluated independently, the framework is applicable across taxa and adaptable to the specificities of diverse signalling systems.

We applied this framework to the “wail” calls that open rock hyrax (Procavia capensis) songs. Combining sound-propagation trials, structural analyses of a long-term acoustic dataset, and field playbacks, we found that wails transmit robustly over short–medium distances, consistently mark the onset of singing bouts, and are shortened or omitted once receivers are likely attentive. Artificial reduction or disruption of wails lowered the probability and, in some cases, increased the latency of conspecific responses. These results support the prediction that wails act as alerting components in rock hyrax songs. More broadly, our framework provides a general tool for studying how animals manage attention, salience, and information flow in noisy, acoustically complex environments.

Many acoustically communicating animals signal in aggregations to attract mates and reduce predation risk. However, this risks acoustic masking interference due to simultaneously signalling individuals. This impairs signal detection and recognition, akin to the ‘cocktail party problem’. Masking is especially severe in conspecific choruses due to higher signal similarity between signallers and due to limited opportunity for acoustic niche partitioning. We examined strategies for masking avoidance in conspecific choruses of a field cricket, Acanthogryllus asiaticus. Field observations showed that males call from choruses of up to 19 individuals, with the nearest neighbour distance being 3 m on average. Sound transmission experiments were conducted to calculate the active space of males and to assess the number of potential maskers for each male. Using the spatial location of all males in 10 natural choruses we reconstructed the active space of each male in a computer simulation. We then computed the degree of masking (active space overlap) suffered by each male in the absence of any strategies to avoid masking. Masking was found to be 40% on average and as high as 98%. Field-based observations, followed by controlled lab playback experiments, showed that natural spacing in combination with inhibitory resetting of calls to alternate with the nearest masker allowed signallers to reduce average masking to less than 20%, even in dense choruses. Notably, these crickets did not exhibit the Lombard effect, a strategy commonly used by other animals to escape masking. Our findings demonstrate that masking avoidance strategies vary significantly across the animal kingdom, and when acoustic niche partitioning is ruled out, behavioural strategies effectively reduce masking even in conspecific choruses.

The diversity of life on Earth, generated via natural and sexual selective pressures, is both the thread and tapestry of evolution. How such diversity originates is particularly hard to study, given the historical lens through which evolution is almost always viewed. However, an unprecedented opportunity has arisen in the Hawaiian islands, where the Pacific field cricket (Teleogryllus oceanicus) is rapidly evolving in real-time due to strong natural selection via the eavesdropping parasitoid fly Ormia ochracea. Gravid female flies listen in on male crickets as they sing to attract females to mate, and parasitised males are necessarily killed by the fly larvae. For over five years, our lab has conducted extensive field surveys, tracking changes in wing morphology and recording the songs produced by such heavily modified wings (indeed, in some cases sound producing structures are nearly, if not entirely, missing). Here, we present the results from analyzing over 1,100 wing photos using both standard morphometric analysis, as well as a generalized measure of dissimilarity across populations and time. Further, we derived acoustic parameters from more than 550 calling songs from unique individuals using a bespoke audio analysis pipeline. Understanding how male phenotype and song are changing in response to parasitism, whilst simultaneously balancing the need to attract mates, helps us to better understand the microevolutionary dynamics which lead to broad scale macroevolutionary change and the maintenance of biodiversity.

Many animals use vocalizations to mediate interactions with conspecifics and heterospecifics. Among many functions, these serve to maintain social and parental bonds, defend territories, and attract mates. Contrary to other seabirds, Atlantic puffins (Fratercula arctica) at colonies are generally quiet. Individuals seldom vocalize on land but there is now evidence they vocalize at high rates in their burrows. Why Atlantic puffins vocalize below ground is unknown. As a first step towards understanding the function of underground calls in puffins, we deployed lapel microphones inside 14 burrows and recorded all vocalizations across the incubation and brood rearing period, providing us with ~30,000 hours of recordings. From these we determined the diel and seasonal patterns of different call types. We also performed a playback experiment before the birds arrived at the nesting grounds, whereby unmodified and modified (higher frequency) puffin vocalizations were broadcast inside burrows and concurrently recorded in three neighboring nests at distances up to 8 m. We repeated the playbacks after stuffing the burrow entrances to prevent sounds from travelling from one entrance to another, and above ground to compare sound degradation above and below ground. The playback experiments were complimented by natural observations of sound degradation by simultaneously recording inside 4 burrows at different times of day during the nesting season. Our results show that Atlantic puffin vocalize throughout the breeding season, with increased rates at dusk and dawn of most days. The playback experiments present strong evidence that the vocalizations travel through the ground, and that calls with natural frequencies suffer less from degradation than calls with artificially increased frequencies. The results from this project will help us establish the potential functions of underground puffin vocalizations and lay the groundwork for behavioral experiments.

Social behavior ranges from simple, transient interactions to complex societies with cooperative brood care and division of labor. Subsocial species, which live in temporary parent–offspring associations, are thought to represent key evolutionary stages in the emergence of sociality. Early social evolution is often associated with regulatory changes that modify the timing and patterns of gene expression underlying social behavior. In my PhD project, I investigated transcriptomic patterns associated with parental and alloparental care in the facultative eusocial ambrosia beetle Xyleborinus saxesenii (Curculionidae: Scolytinae). This cooperative fungus-cultivating beetle exhibits sibling mating and haplodiploidy, parental care, division of labor between adults and larvae, larval cooperation, and delayed dispersal of some adult daughters that provide alloparental care despite being capable of independent reproduction. We generated head and abdominal transcriptomes from adult females during a solitary phase, three distinct parental care phases, and from adult daughters remaining in the natal nest. In addition, we analyzed transcriptomes from larvae at second and third larval stages. Gene expression profiles differed significantly among all adult female phases and between larval stages. The strongest transcriptomic shifts occurred between post-hatching caring mothers and nest-staying daughters, as well as during the transition from nest-staying daughters to dispersing females. Notably, genes associated with Juvenile Hormone signaling showed elevated expression in dispersing females and caring adults compared to nest-staying daughters. These results suggest that transitions between caregiving, helping, and dispersal states are accompanied by pronounced regulatory changes, supporting the idea that behavioral flexibility in facultatively eusocial species is underpinned by dynamic gene expression rather than fixed caste-like programs.

Lateralisation, colloquially referred to as handedness, is a cognitive process where information is processed asymmetrically between brain hemispheres and results in behavioural biases. Laterality is widespread in vertebrates and may enhance individual fitness particularly in social contexts. Lateralised individuals can exhibit improved spatial orientation, cognitive performance and escape responses. In group-living animals, lateralization could, therefore, offset the costs of competition by enabling faster decision-making. We tested how laterality influences responsiveness to an ephemeral food source in shoals of three-spined sticklebacks (Gasterosteus aculeatus). More strongly lateralised individuals were more likely to first attack the food stimulus and did so more rapidly. The direction of laterality (left- or right-biased) had no effect on performance. Motivation (being less satiated) increased the likelihood of attacking first, whereas proximity and orientation to the food source reduced attack latency but did not affect who attacked first. Unlike previous studies, shoals consisting of individuals with higher mean laterality were less cohesive. These findings suggest that laterality, regardless of direction, enhances individual foraging efficiency in group contexts, indicating that laterality may be favoured by selection in gregarious species.

Colour patterns are among the most striking and diverse traits in animals, yet our understanding of the evolutionary drivers of this diversity remains incomplete. In particular, our understanding of how these signals shape the formation and maintenance of cooperative social groups remains limited. Here, we combine laboratory and field studies to investigate whether body colour and bar pattern in the clown anemonefish, Amphiprion percula, function as social status signals to facilitate group formation and maintenance. Using controlled laboratory experiments, we examined plasticity of colour pattern development in juveniles settling as different social ranks and tested behavioural responses to size-matched fish with different body colours and bar patterns. Complementing this, using a field experiment, we tested whether individuals modify their colour and pattern in response to changes in social status within natural groups. Our results show that juvenile anemonefish delay colour pattern development to reduce conflict with dominants, a strategy likely crucial during recruitment and thus a key mechanism in the formation of social groups. Our findings provide new insight into the developmental plasticity and fitness benefits of colour patterns in cooperative animal societies.

Social animals often cooperate by producing public goods, which benefit their whole group: sentinel behaviour and contribution to intergroup conflict are examples of such public goods scenarios. Because individuals benefit even if they do not contribute, the production of public goods is vulnerable to collapse if there are insufficient incentives to contribute. Payment or ‘reward’ based on the contribution that an individual makes to a public good has been shown theoretically to promote cooperation and observed empirically in several species. However, it remains unclear how individuals should allocate rewards to promote public goods contributions. In this study, we developed a game theoretic agent-based model with multiagent reinforcement learning to identify how rewards should evolve in the context of a group of individuals learning how to maximise their fitness in a public goods game. We found that the evolved rewards for public goods contribution depended on ecological context and the nature of the reward provided; the highest rewards were given when both the cost and benefit of contribution was high, and the reward was a reasonably common (but not ubiquitous) affiliative behaviour. By investigating this question over two timescales – that of an individual’s life and evolutionary time – we show how cooperative decisions within the lifetime of an individual can impact the trajectory of the evolution of a related trait within a group and vice versa.

Species’ responses to environmental variability can include evolutionary changes in social behaviours, leading to variation among species in characteristics including their mating systems, care systems (e.g., cooperative breeding), the rate of group formation, and the strength of interaction between individuals. These sociality traits can influence the physiology of individuals and the demography of populations and species, potentially shielding individuals from adverse environmental conditions. The demographic consequences of sociality have rarely been studied and have been limited to ecological timescales. Across evolutionary timescales (thousands-to-millions of years), anecdotal comparative evidence based on a few species suggests that social traits lower effective population size while also buffering species demographic responses. Here, we used whole-genome sequence data to reconstruct the deep-time demographic history of 630 populations of 322 bird species over half a million years. We then explored the role of different sociality traits (cooperative breeding, flock size, mixed-species flocking propensity) in buffering the long-term demography of species. Contrary to previous studies, our large-scale comparative analyses found no clear evidence of sociality influencing and stabilising the demography of bird populations. This finding highlights that the role of sociality on species’ demography across evolutionary timescales might be taxa-specific.

In mammals, maternal care is essential for offspring survival, shaping early development and social behaviour. In species with fission–fusion societies, where individuals frequently join and leave groups, maternal associations may also influence the social structure of colonies. Yet, the importance of these dyadic interactions remains poorly understood in bats. Using eleven years of daily roosting data from two colonies of Myotis bechsteinii, we investigated the strength and temporal stability of mother–daughter associations and their role in shaping social network structure.

Across both colonies, mother-daughter pairs were more strongly associated than other female dyads, particularly during the daughter’s first summer. But the strength of these associations varied across years and demographic contexts. In a colony with stable growth, overall associations among colony members declined as colony size increased, yet mother–daughter dyads showed higher association strength, suggesting that maternal bonds are less sensitive to demographic change. In contrast, in a demographically stable colony, association patterns were more uniform across dyads.

Although mother-daughter pairs have a stronger bond in their first year, this bond is not more stable in the long term than other female bonds. Across all dyad types, we observe a positive relationship between association strength and the relationship age, suggesting that repeated co-roosting can lead to strong social bonds even between non-kin females.

Finally, mothers with multiple daughters occupied highly central positions in the networks but were less closely connected to all colony members, suggesting that maternal bonds create local clusters among mothers and daughters rather than broad connections across the colony. These results highlight the important role of maternal relationships in fission–fusion societies and emphasize how long-term data can reveal demographic-dependent changes in the social structure of bats.

Cleaner species play a vital role in coral reef ecosystems through mutualistic cleaning interactions that influence fish health, behaviour, and community structure. In the Indo-Pacific, the removal of the cleaner wrasse, Labroides dimidiatus, can lead to declines in fish abundance and diversity and reduce herbivory rates; however, evidence of the latter effect is mixed. Furthermore, cleaner wrasse may influence farming damselfish recruitment, as more juveniles recruit to reefs with cleaners. However, how this increase in damselfish density affects territory size and reef benthos is unknown. We investigated the long-term effects of cleaner wrasse on fish behaviour and reef structure using an ongoing removal study at Lizard Island, Australia. Firstly, we explore the effect of cleaner wrasse on the behaviour and community dynamics of reef fish, including territorial aggression, feeding, and cleaning interactions, using underwater video recordings. Secondly, we investigate how cleaner wrasse may indirectly mediate the spatial and structural characteristics of damselfish territories and the surrounding reef. We used structure-from-motion photogrammetry to create 3D models of the reefs and calculated spatial metrics including surface area and rugosity. By comparing experimental and control reefs, we explore the effects of cleaner fish across ecological levels - from individual foraging behaviour to community dynamics and habitat structure. This study provides an in-depth, multi-scale assessment of the ecological roles cleaner wrasse play in reef systems by analysing both behavioural and spatial data. Our findings emphasise the significance of mutualistic cleaning species and the importance of preserving these key ecological interactions.

Keywords: Cleaner fish, Behavioural interactions, 3D Habitat Structure

Urbanization is often framed as an individual-level challenge, yet for social hunters it may act first at group level. By reshaping prey communities, and especially by removing the largest, more profitable prey, cities can change the payoffs of cooperation and force groups to reorganize their collective foraging. Sociality is a major evolutionary transition, yet we still know little about how group-level shifts mediate responses to human-altered environments. Using the permanently social spider Anelosimus eximius, we trace a bottom-up pathway from urban shifts in prey communities to collective foraging and reproductive output. Across replicated paired forest–urban sites in the Ecuadorian Amazon, urban sites supported markedly poorer prey landscapes. Total insect biomass was ~1.8 times lower, and prey size distributions were truncated, especially for the large insects that fuel colony growth and persistence. Female body size was unaffected, but urban colonies were ~33% less dense, suggesting that energetic constraints emerge at the group rather than the individual level. In standardized foraging assays with large prey, urban colonies recruited almost half as many attackers yet subdued prey ~40% faster. Field scans showed a pronounced shift to nocturnal collective activity. In cities, activity tripled from day to night, and the probability of prey capture at night was ~4-fold higher than by day, but forest colonies still captured more prey biomass. These behavioural adjustments only partly compensated for reduced resources. Urban colonies produced ~1.6 fold fewer embryos per egg sac, although colonies with stronger nocturnal shifts produced ~14% more embryos per standard deviation increase in that shift. Overall, urbanization rewires collective foraging and activity rather than shifting individual phenotypes. Colony-level plasticity provides a key buffer, but it is a quantitatively limited axis of resilience when large prey are lost.

It has been proposed that intense conflict between groups can drive the evolution of cooperation within them. However, intergroup interactions are not always aggressive: in many species, groups tolerate or even cooperate with rival groups, but little is known about what drives this variation. Here, we test the hypothesis that a ‘common enemy’ promotes cooperative intergroup interactions, using laboratory colonies of the Pacific dampwood termite, Zootermopsis angusticollis. Wild Z. angusticollis colonies live in rotting logs and interactions between colonies within a log can vary from lethal fighting to peaceful fusion. To test our hypothesis, we placed two size-matched ‘focal’ colonies (of varying relatedness to one another) side by side and kept them separated by a piece of mesh. After 2 days we introduced a ‘common enemy’ colony of varying size and subsequently removed the mesh separating the pair of focal colonies to observe their intergroup interactions. Rates of affiliative (allogrooming, trophallaxis & antennation), agonistic (biting, lunging & grappling) and alarm behaviours (recoil & vibration) between the pair were measured. With analysis ongoing, our preliminary findings suggest that: 1) the presence of a common enemy presence may increase rates of affiliative behaviour between focal colonies, and decrease rates of agonistic and alarm behaviours; 2) affiliative behaviours vary with genetic relatedness between colonies; 3) affiliative behaviours may increase with the size of the common enemy group; 4) reproductive castes are particularly vulnerable during intergroup interactions. Our study suggests that a common enemy may promote fusion between colonies, likely because joining forces offers a size advantage against a shared threat. These results contribute to our understanding of intergroup behaviour and how intergroup cooperation and conflict shape the evolution of societies.

In forest bird mixed-species flocks (MSFs), individuals rely heavily on acoustic communication for locating flock mates, finding food, and avoiding predators. Sound travels long distances and is less obstructed by dense vegetation compared to visual cues. Such reliance on sound plays a key role in flock formation, cohesion, and coordinated movement. MSF participants in these systems of insectivorous birds can be grouped based on their social and foraging guilds, into intraspecifically gregarious gleaners, solitary gleaners, and solitary sallyers. Species from these functional guilds are expected to differ in how attractive they are to other flock members based on the ecological benefits they provide. MSF participants are expected to make decisions based on the cost-benefit trade-off they face at the hands of other flock members, hence expected to show preferences for joining particular guilds.

To test this, we conducted playback experiments with MSF members in the forests of the Western Ghats, India. For each functional guild, we selected two common participant species, recorded their vocalisations, and played them back in the study site. We then measured heterospecific responses — including which species approached, number of individuals, latency of arrival, and distance from the speaker. Our results show that gregarious gleaners attract the highest number of heterospecific flock participants, followed by solitary sallyers and then solitary gleaners. This research offers the first field-based experimental evidence that acoustic attractiveness varies across functional guilds in the MSFs of Western Ghats. Our results indicate that trait-based interactions influence the composition and organisation of MSFs, while species interactions govern the roles that species take up in such groups in structuring avian communities in complex forest ecosystems.

Pair bonding is a social structure consisting of a dyad of adult conspecifics maintaining a unique long-term attachment. Though overall rare, pair bonds can be found in species across mammals, birds, amphibians, reptiles, and fish. The major putative benefit of pair bonding is increased reproductive success, whether through avoiding the cost of finding a new mate each season, shared resource defense, and/or biparental care of young. Therefore, if reproductive success is reduced beyond a critical threshold, members of the pair should seek to increase their individual fitness, potentially by severing the existing bond and searching for a new partner. However, few empirical studies testing these predictions exist, and those that do are limited to mammals and birds. To fill this gap, we explored the importance of reproductive success to bond strength in the mimic poison frog (Ranitomeya imitator), one of the few pair bonding amphibians. We manipulated the reproductive success of bonded pairs (n = 12) for 6 weeks and tested bond strength and reaction to a stranger using behavioral assays before and after the treatment period. We reduced the treatment group’s reproductive success by euthanizing every other clutch of eggs, while the control group’s reproductive success remained unaltered. Preliminary results suggest that after treatment, pairs with reduced reproductive success exhibit weaker pair bonds and higher affinity for opposite sex strangers. These results affirm the importance of reproductive success in maintaining the pair bond, providing valuable insights into the understudied world of amphibian sociality. Future work will explore other putative benefits of pair bonding, including biparental care and resource defense, and ask how reproductive success contributes to the formation of new pair bonds.

Thermal constraints on foraging and provisioning are associated with declines in breeding success during hot weather in many bird species. However, fork-tailed drongos (Dicrurus adsimilis) in the Kalahari produce fledglings of consistent size and mass even during heatwaves, despite suffering reduced foraging and provisioning under high air temperatures. We hypothesised breeding drongos might compensate for reduced foraging during hot periods by increasing foraging and provisioning at cooler times of day. We used supplementary feeding experiments (n= 250 trials with 16 drongo pairs), which controlled prey availability, to examine drongos’ foraging and provisioning behaviour throughout the day relative to air temperature (Tair) at the time of observation and daily maximum Tair (Tmax). We also measured nestling mass (g) and tarsus length (mm) on the morning and evening of Day 7 and mornings of Day 8 and Day 12 post-hatch. Tair ranged from 12.1–40.3°C during this study. Foraging activity declined with Tair in the afternoon (Estimate = -1.35 ±0.43, 95% CI -2.18/-0.49), but not in the morning or evening. Drongos reduced provisioning rates on hot afternoons but compensated by increasing provisioning on hot mornings (0.44 ±0.12, 95% CI 0.21/0.67), with no effect of Tmax on overall daily provisioned totals (0.02 ±0.06, 95% CI 0.36/0.72). Our findings suggest drongos flexibly adjust provisioning during cooler periods to maintain stable prey delivery to nests over whole days regardless of Tmax. As prey availability was controlled, results cannot be explained by temperature-driven invertebrate activity. However, overall provisioning did not increase on hot days, despite likely higher offspring energy and water needs for thermoregulation on hot days. Despite this, nestling mass and tarsus growth on Days 7-8 and 12 were unaffected by Tmax. Drongos might therefore also use other behavioural adjustments (e.g. shading nests) to reduce impacts of high temperatures on nestling growth.

The pupal stage, despite its relative immobility and high vulnerability to predation, has persisted throughout lepidopteran evolution due to the developmental advantages of complete metamorphosis. To avoid predation and environmental stress during this stage, butterflies exhibit diverse protective features, including specialised attachment mechanisms to a stationary substrate. The silk pad, produced by the last-instar larva on a substrate, can anchor the pupa by either a one- or two-point attachment system based on species, and its effectiveness depends on the strength and extent of silk investment. Because silk is a relatively metabolically costly protein, we hypothesized that larvae exhibit adaptive plasticity in silk allocation based on the physical properties of the pupation substrate.

Using the butterfly Danaus chrysippus, we tested how substrate roughness influences silk pad investment. Wandering larvae were allowed to pupate in a controlled arenas lined with substrates of varying roughness: OHP sheet, chart paper, and sandpapers of different grades - P600, P80, and P50. After pupation, silk pads were imaged under angled white light and quantified using ImageJ.

Silk pad surface area varied significantly across substrates, showing a clear negative relationship with increasing roughness. The largest pads were produced on the smoothest substrates (OHP and chart paper), which did not differ significantly between them, while progressively smaller pads were constructed on P600, P80, and P50 sandpapers. Among the sandpapers, P50 yielded the smallest pads and differed significantly from P600.

These results reveal substrate-dependent plasticity in silk investment during pupal attachment in D. chrysippus, highlighting how larvae modulate costly material allocation in response to environmental heterogeneity.

Behavioural flexibility enables animals to adapt to changing environments. An appropriate physiological stress response is crucial for this flexibility: short-term stress can enhance cognitive function, whereas prolonged stress may impair attention and memory. The concept of allostatic load (sensu McEwen & Wingfield, 2003) suggests that overnutrition may further interfere with stress recovery and, consequently, reduce behavioural flexibility under prolonged stress.

In this study, we investigated the relationship between nutritional status, behavioural flexibility, and stress responses in rainbow trout (Oncorhynchus mykiss). Fish were assigned to two feeding regimes for one month, representing reduced and excessive food availability. Behavioural flexibility was assessed using a detour task, and stress responses were evaluated through cortisol measurements. We predicted that fish receiving excessive food would show lower behavioural flexibility and higher cortisol levels following an acute stressor compared with fish on a reduced feeding regime.

Our results showed that fish with reduced food availability exhibited greater behavioural flexibility in the detour task and higher plasma cortisol levels following the stressor than fish with excessive food availability. This suggests that fish under reduced feeding conditions were better able to cope with acute stress. Long-term cortisol concentrations measured in scales did not differ between the groups, possibly due to the absence of prolonged stress exposure.

Overall, our results partially support the hypothesis that excessive food consumption may impair behavioural flexibility and the ability to cope with novel stressful situations. These findings have important implications for animal welfare, as farmed animals are often maintained under conditions of overnutrition.

The warming of global surface temperatures and increasingly frequent extreme climatic events drastically modify the selective pressures acting on living organisms. While avian breeding phenology has attracted a lot of attention in the context of adaptation to climate change, breeding effort and success have been surprisingly rarely explored. Using a four-decade study in three Mediterranean blue tit (Cyanistes caeruleus) populations, we investigated whether birds used to increase pre-breeding temperatures as a reliable cue for climate conditions during breeding, and whether they reduced their clutch size in response to these pre-breeding temperatures. In the three populations, birds laid smaller clutches in response to increased pre-breeding spring temperature, with notable differences in the magnitude of reduction and in the temperature cue reliability between populations. Fledging success decreased with temperature during breeding in populations where birds did not reduce their clutch size or got unreliable cues. In one population (E-Pirio), by decreasing their clutch size in response to pre-breeding temperature, birds maintained a stable fledging success independent of temperature during breeding, suggesting adaptation to climate change. Our results show population differences in the responses to climate change, highlighting the complexity of predictions on populations and species persistence in future environments. We discuss how integrating life-history and behavioural syndromes could refine our understanding of the mechanisms responsible for global change adaptations.

The social environment experienced during development plays a crucial role in shaping social competence—the ability to respond appropriately to social challenges. Sibling number and the social interactions between them are key components of the early lives in many animals. While these components are well known to influence social development in humans, their role in non-human animals remains unclear. Here, we show that both the number of siblings and opportunities for social interaction are essential for developing social competence in the highly social cichlid Neolamprologus pulcher. We reared N. pulcher either in large broods (LB), small broods (SB), or large broods with restricted social interactions (4x8). Fish reared in LB displayed more affiliative and fewer aggressive or submissive behaviours during early life compared to those reared in SB or in 4x8 groups. Later in life, LB fish were more socially competent. Thus, social competence arises not from the number of individuals or interactions alone, but from the combination of both.

08 08. Movement and collective behaviour

Morphological traits are key determinants of social interaction outcome, such as contests among competing animals. However, the link between morphological variation and variation in social behaviour remains unclear: to what extent differences in morphology among contestant explain differences in aggressive behaviour during contests? And what is the relative role of behavioural plasticity versus behavioural consistency in generating this variation? To address these questions, we quantified how non-genetic variation both among and within individuals contributes to differences in contest behaviour in the territorial and highly aggressive fruit fly Drosophila prolongata. We found that even in a genetically uniform population maintained under highly standardised conditions, small differences in key morphological traits (i.e. body size and weapon size) still emerged. Strikingly, this relatively limited morphological variation explained over one-third of the variation in contest behaviour. Overall, our findings highlight the importance of consistent individual differences and behavioural plasticity in response to social partners in generating behavioural diversity within populations.

Innate behaviours have often been described as stereotyped and robust, yet they can be flexibly modulated depending on context. However, the mechanisms governing such plasticity remain poorly understood. In this study, we investigated the plasticity of an innate visually guided behaviour in ants, termed beacon-aiming. This behaviour is defined as a spontaneous approach towards a conspicuous visual landmark, typically a dark vertical stripe. Beacon-aiming is often classified as a form of scototaxis and is widely reported across insects. A comparative analysis of six ant species revealed that, unlike the other species examined, workers of the Japanese carpenter ant, <i>Camponotus japonicus</i>, did not exhibit beacon-aiming. However, when they fell onto a water surface, they approached the landmark while swimming or wading. Beacon-aiming was also induced when <i>C. japonicus</i> workers fell onto a non-aqueous liquid surface (a glycerol–2-propanol mixture), walked upside down under dry conditions, or were exposed to strong upward airflow, whereas weak upward airflow did not induce this behaviour. Although these experimental manipulations differed in their physical nature, they shared a common feature in that they imposed adverse constraints on locomotion or posture, thus suggesting that beacon-aiming is selectively triggered under conditions associated with “stress.” In addition, experiments involving sequential substrate transitions (land-to-water and water-to-land) revealed that beacon-aiming emerged gradually prior to the transition into an adverse substrate (water) and persisted for at least several seconds after the transition to a non-adverse substrate (land). Our findings demonstrate that an innate visually guided behaviour that is not exhibited under standard conditions can be plastically induced through stress-dependent modulation.

Dynamic color change is a rapid form of phenotypic plasticity that serves as a real-time indicator of an animal's motivational state. While these mechanisms are well studied in cephalopods, the temporal dynamics and functional ecology of rapid color signalling in marine fishes remain poorly quantified. Emperor fishes (Lethrinidae) are ecologically significant mesopredators known for transient coloration, yet they currently lack a systematic ethogram. This study bridges this gap by providing a quantitative, multi-species analysis of their signalling repertoire, testing hypotheses on signal function and social complexity.

We analyzed an extensive Baited Remote Underwater Video (BRUVs) dataset (2021-2025) for three sympatric species; Lethrinus nebulosus, L. harak, & L. olivacues. This non-invasive approach captured natural behaviors undisturbed by divers. We used BORIS to log behaviors to quantify temporal kinetics, including transition speeds, latency of onset, and duration. We specifically tested the influence of behavioral states, the differentiation of signals during conspecific versus heterospecific interactions, and the role of habitat complexity (reef vs. sand).

Our analysis identifies a complex signalling system where color states are strictly linked to behavioral context. High-contrast patterns, such as vertical bars, act as reliable signals of aggression with rapid transition speed (<3seconds), while mottled camouflage patterns exhibit slower onset dynamics. We also found a positive correlation between social group size and signal repertoire complexity, confirming that Lethrinid color changes constitute a structured visual language.

This study challenges the view that complex signalling is rare in non-territorial predators. By mapping the "behavioral-color space" and analyzing transition probabilities, we provide a functional "dictionary" of signals. We see that emperor fish use visual syntax to manage competition and navigate social and environmental stimul

Learning is a critical adaptive mechanism that enables animals to navigate complex and changing environments. In temperate climates, this capability is tightly linked to seasonal adaptations. The common shrew (Sorex araneus) provides a unique opportunity to test how learning performance is affected by within-individual seasonal variation in brain size. This species undergoes Dehnel’s phenomenon, a reversible winter reduction in body and brain size that conserves energy but may constrain cognitive function. Because this shrinkage varies across brain regions, different types of learning may be differentially affected. In addition, effects of captivity may confound differences in performance. We tested spatial, associative, and path integration learning in wild and captive shrews across seasons. Shrews consistently performed better in spatial learning than in associative or path integration tasks. In the associative task, winter shrews—both wild and long-term captives—showed reduced performance compared to summer individuals, particularly in early trials. Captivity was also associated with poorer associative learning. In contrast, spatial learning remained relatively robust across conditions, and path integration performance was generally low and showed little evidence of improvement over trials. Our results demonstrate that the cognitive impact of seasonal brain plasticity depends on task demands and brain region involvement. These findings highlight the importance of cognitive flexibility for survival in dynamic environments and emphasise that captivity may alter learning performance.

Rapid climatic warming is increasing the frequency and intensity of heatwaves, yet we still don't have a comprehensive knowledge about how early-life thermal stress shapes development and adult sexual behaviour — particularly in species which are experiencing prolonged higher temperatures and where mating involves complex, sex-specific interactions. In a very recently conducted lab study, we use the tropical cricket Gryllodes sigillatus to experimentally test how developmental heat stress influences life history and shared mating traits in both sexes. Individuals were reared, from egg until adulthood, under an ecologically and biologically relevant high temperature regime (36 °C). Data from a full factorial mating design showed striking sex-specific effects: females developing at high temperature were significantly heavier as adults (p=0.01) than their control counterparts (27°C), with delayed mating onset and prolonged mating latency (p=0.02), whereas heat-stressed males courted far less frequently than controls (p= 0.001) and therefore had a lower probability of gaining a mating. Despite these strong behavioural shifts, some other traits such as copulation duration, and nuptial-gift feeding time were largely unaffected by either sex’s developmental temperature. We are also able to show that heat sressed males are largely unsuccesful in mating (i.e. in transferring sperm) rendering them 'sterile'. The life history and fitness data is still under analysis but we expect strong rearing temperature effects on those traits as well. This study is a comprehensive account of the detrimental effects of development heat exposure and potential implications for sexual selection, mate choice, and population persistence under climate warming.

Circadian clocks are endogenous oscillators that enable organisms to adaptively anticipate daily changes in the environment such that their behaviours are appropriately aligned to daytime and nighttime. While circadian clocks must maintain fidelity to time of day, the timing of output rhythms is predicted to be plastically altered in certain circumstances, such as seasonal temperature changes, food limitation, and elevated predation risk. In particular, semi-field experiments suggest small nocturnal animals become active during the daytime as an energy-saving strategy under conditions of low food and temperature. We test this hypothesis using wild wood mice (Apodemus sylvaticus) by asking whether food availability impacts the timing of daily rhythms in locomotor activity across seasons in a natural woodland. Our field site consisted of 3 grids with either centrally located feeders, evenly spread food, or no food supplementation; wood mice were fitted with RFID tags enabling their unique identification and collection of locational data via detection by static RFID proximity loggers placed throughout grids. We found that wood mice are largely nocturnal across seasons, however food-limited mice (with no access to additional supplemented food) undertook more daytime activity, especially under energetically demanding conditions, such as cold temperatures. Our findings highlight that variable environmental conditions alter the balance between robustness of circadian clocks and plasticity in the timing of behaviours, revealing an overlooked strategy to maximise fitness.

Accuracy in choices between numerical quantities typically increases with the quantities’ difference and, for a given difference, declines with their mean. The latter is a regularity known in psychophysics as Weber’s Law. These properties impose constraints on ubiquitous ecological functions, including decisions involving the sizes of food bundles, broods, or social groups, but responsible mechanisms are not well known and hence their inclusion in normative models is limited. The effects may be driven by properties of perception, memory encoding, memory retrieval, the cognitive operations involved in comparisons and decision making, or by motivation (differences between larger quantities may matter less). To explore this, we presented 11 red-and-green macaws (Ara chloropterus) with choices between either quantities of seeds (1,3,5,7 or 9 seeds presented in pairwise comparisons) or pairs of colored tokens associated with the same seed quantities. The proportion of choices for the larger option within each pair of seed quantities ranged between 0.57 and 0.87, increasing with within-pair difference and, for a given difference, declining with the mean, in accordance with Weber’s Law. When choosing between tokens, the overall proportion of choices for the larger quantity was similar to seeds (ranging from 0.59 to 0.84) and also increased with difference. However, for a given difference, performance did not decline with mean. This result is compatible with Weber’s Law being driven by perceptual constraints (quantity evaluation) rather than upstream cognition or motivation, because discrimination between seeds requires counting or estimating quantities, while perceptual discrimination of tokens of different, randomized colors is independent of their associated quantities but should preserve cognitive and motivational processes.

Suboptimal diets have long been known to negatively affect sleep quality, and lack of sleep has profound effects on learning performance. However, whether optimised diets can counteract the effects of sleep deprivation, or how diet choice in interaction with sleep patterns affect cognition, are largely unexplored questions. We here investigate the interactive effects of protein concentration and sleep regimes on sex-specific cognitive performance across the lifespan in the model organism Drosophila melanogaster. Specifically, flies were tested in age-specific cohorts (young, middle-aged, old, very old) on their performance of solving a maze. We manipulated dietary protein levels (low, control, high) and sleep regimes (12:12 hr light:dark cycle vs 24 hr constant light to induce sleep deprivation) in a total of 576 individuals. Each fly underwent 10 maze exploration trials during which we measured activity levels, total distance moved and ability and speed in solving the maze. Unsurprisingly, activity and maze solving levels markedly decline at older ages in both sexes, and performance is generally depressed in sleep deprived flies. However, we anticipate to find highly complex, non-linear age- and sex-specific effects between dietary protein levels and sleep regimes. Our experiment highlights the necessity of interactive study designs to untangle these intertwined relationships among sex, sleep, diet, and cognition. The results will illuminate whether dietary intervention can serve as a viable, sex-specific therapeutic target for mitigating the widespread cognitive decline associated with chronic insufficient sleep.

Cognition and its variance are key components of animals’ adaptive responses to environmental challenges, prompting growing interest in their role in coping with global change. One of the main threats to biodiversity is hybridisation with non-native species introduced outside their natural range by human activities. Hybridisation can affect both the average value and the variance of traits, as well as their covariance with other traits. Recent experimental studies also suggest a potential impact of hybridisation on cognition. All this raises the question of the effects of hybridisation on cognition and its variance. Here, we investigated these effects in the endangered marble trout (Salmo marmoratus), a large predatory fish endemic to the rivers of the Adriatic basin. We used a study system in the Gran Paradiso National Park characterised by spatially segregated populations with different levels of genetic introgression from the invasive brown trout (Salmo trutta). We found that high levels of hybridisation were associated with enhanced spatial learning abilities in trout. In addition, a network analysis approach used to study covariation between cognitive and behavioural traits suggested that high levels of hybridisation substantially reduced the significant associations. These findings indicate that hybridisation with invasive species can influence cognition in endangered fish in a twofold way: by conferring a direct cognitive advantage through improved performance, and by indirectly increasing evolvability potential through relaxed covariance constraints. Such a cognitive edge in hybrids could further exacerbate the negative impacts of hybridisation on remaining native populations, especially in changing environments.

Boredom is an unpleasant affective state arising when stimulation is insufficient for optimal arousal. It manifests both as inactive behaviour, e.g. lying awake, and as active arousal-seeking behaviour, e.g. restlessness, escape, risk-taking. Initial studies focus on captive animals, but findings may apply in the wild. I aim to prompt animal boredom research across Tinbergen’s four ‘whys’.

Regarding external causes, lack of novelty, complexity or variety in environments for captive mustelids and rats increase behaviour consistent with boredom, e.g. escape attempts and lying awake. Internally, boredom is caused by high motivation for stimulation and low actual sensory input; potentially when the mesolimbic dopamine pathway is highly active, while neural arousal systems reliant on sensory information are relatively inactive.

Turning to ontogeny, human boredom proneness varies with development, with risk-taking and novelty seeking cresting during adolescence. Similarly, risk-taking, novelty seeking, and impulsivity peak in adolescent rodents. Individual differences in boredom proneness may contribute to behavioural syndromes, correlating with boldness, neophilia and impulsivity, with or without age-related phenotypes.

The likely adaptive value of boredom is to prompt switching away from unrewarding or uninformative activities. It may thus facilitate learning, exploration, innovation and niche expansion. In captivity, barren environments cause neural degeneration; barrenness is too extreme and recent a challenge to be directly evolutionarily relevant, but this suggests that boredom helps prevent behavioural inflexibility.

Finally, phylogenetic reflections suggest boredom should be most evident in generalist, neophilic and innovative species, which appear to most seek stimulation in captivity. Comparative research on boredom across taxa could clarify its neural basis, evolutionary distribution, adaptive value, cognitive implications, and animal welfare relevance.

The formation of habits, whereby learnt actions come to be performed automatically with repetition and practice, is a well-established focus for studies in psychology. This contrasts with studies of learning in behavioral ecology, which typically view behavior as either learnt or fixed to elucidate the ecological conditions where each predominates. Here, we envisage habit formation functioning to free up limited mental resources (e.g., attention), potentially improving an individual's ability to multitask. As an ecologically relevant case, we investigate exploration-exploitation in foraging under predation risk. In our model, a forager does not know the quality of feeding options, but can learn from the rewards they give. When the environment occasionally changes, individuals can respond to cues that indicate a change and reset their attention to exploration of feeding options in the new conditions. The options can then become habitually exploited, freeing attention for anti-predatory vigilance. Via evolutionary simulations, we show that evolutionarily stable forming and breaking of foraging habits can substantially reduce mortality from predation, without drastically reducing foraging success, when environmental conditions remain stable enough between changes. We therefore argue that exploration-exploitation strategies involving the forming and breaking of habits is a type of behavioral flexibility that is likely to be selected for under a range of ecological conditions.

Higher cognitive ability is a fundamental determinant of species persistence, especially under environmental change. The ability to perceive and solve problems by modifying behaviour are essential for survival and reproduction in unpredictable conditions, allowing an individual to adapt to meet new environmental demands. The ecological intelligence hypothesis suggests that complexity relating to fluctuations and variation in food sources drives the development of cognition. We may therefore expect more structurally complex environments to promote higher cognitive abilities development, thereby increasing an individual’s behavioural flexibility and capacity to learn and adapt. Evidence supporting complexity-driven cognition exists across a range of taxa, from mammals and birds to fish and insects. However, many studies, if not all, focus of simple levels of structural complexity, such as high and low, whereas the significance of fine scale structural complexity is unexplored. We raised three species of settlement-stage reef fish on a continuum of structural complexity to test how fine scale structural complexity drives multiple cognitive domains: spatial learning and memory, cognitive flexibility, object permanence and inhibitory control. Coral reefs are highly structurally complex habitats and exhibit wide variation in their fine scale complexity. By exploring a more precise range of complexity, we detail how fine scale structure may drive cognitive abilities across domains and identify nuances in the complexity-cognition relationship. In doing so, we illuminate how environmental disturbances and rapid reef flattening may affect the ability of coral reef fish to adapt and survive in a changing world.

Affective states shape how animals evaluate outcomes, regulate cognition, and interact socially, yet their existence and functional roles in insects remain debated. In this talk, I present evidence that bumblebees possess affective states that can be traced from expression to function. Bumblebees exhibit discrete post-consumption orofacial reactions, glossa protrusions to rewarding solutions and head-shaking or mouth-wiping to aversive ones, providing a behavioural marker of affective evaluation that is comparable, in functional terms, to mammalian liking. Beyond expression, affective state in bees influences how information is processed and used. Experimentally induced affect biases both memory encoding and retrieval in a mood-congruent manner, shapes decision-making under ambiguity, and modulates behaviour following social interaction with conspecifics. In particular, positive affect can be socially transmitted between individuals, giving rise to affective contagion even in the absence of physical contact. Together, these findings suggest that affect in bumblebees acts as an internal state linking evaluation, cognition, and social interaction, and that affective states and their functions may be evolutionarily conserved across phyla.

In recent years, animal cognition research has become an important topic in behavioural ecology. As there are long traditions of studying animal cognition in classical ethology as well as in experimental and evolutionary psychology, behavioural ecologists can greatly benefit from integrating the existing knowledge into own research. I will give selected examples from our research on the cognitive abilities of cleaner fish Labroides dimidiatus to illustrate i) how an ecological approach to cognition has helped to uncover abilities that were hitherto unknown in fishes, and ii) how borrowing from established fields has helped to advance our understanding of both cognitive mechanisms and cognitive constraints that affect cleaner fish decision-making. Ultimately, an evolutionary approach to animal cognition should aim at identifying the costs and benefits of brains to explain the enormous variation in brain size relative to body size across vertebrates.

Artificial selection on relative brain size in guppies (Poecilia reticulata) leads to differences in learning performance in various learning contexts. But till now, little is known about potential differences in learning styles in these selection lines and how such potential effects might interact with learning efficiency. To assess this, we tested adult females of the large- and small-brained lines (N=27) for side-discrimination associative and reversal learning. Based on recordings of all trials (about 1550 videos), we conducted detailed scoring of 11 behaviours (e.g. latency to approach the task, number of switches between sides, latency to reward retrieval) that could reflect variation in individual decisiveness, flexibility, information gathering, motivation, and behavioural efficiency. Multivariate analyses revealed that, while the lines did not differ in behaviours related to motivation, large-brained fish (1) had lower levels of indecisiveness, (2) spent less time around the rewarded side, and (3) were faster to find the reward than small-brained fish. This suggests faster information processing, decision-making, and/or habit formation in large-brained fish, showing that relative brain size might shape learning styles, leading to more efficient collection and use of information. Our study highlights that cognitive comparisons based solely on one learning criterion might not fully depict the complex patterns of variation in individual learning. We advocate for implementation of more fine-tuned multivariate approaches in cognitive tests.

Navigating a complex social landscape may require knowledge about ranks of other individuals and the ability to inhibit aggressive interactions that might result in a loss of rank. This aggressive decision-making should be partly mediated by inhibitory control ability, the suppression of an impulsive behaviour in favour of more beneficial one. However, while the link between aggression and inhibitory control is supported by comparative and population-level evidence, there is relatively little individual-level study. We investigated the link between rank, inhibitory control and social decisions in a population of wild sulphur-crested cockatoos, a highly social parrot that forms stable linear dominance hierarchies. We recorded 1062 aggressive interactions between 96 individuals, and used this to construct dominance hierarchies, aggression networks, and to quantify the aggression heuristics employed by individuals. We found individual and rank-dependent variation in propensity to use a downward (aggressing uniformly against lower ranks) or close-competitor heuristic (aggressing individuals close in rank). We then tested inhibitory control in 21 individuals with the classic detour-reaching paradigm, where individuals need to inhibit the impulse to tap the front of the box and instead detour to either of the open faces to obtain a food reward. Inhibitory control performance was quantified in two ways (a) proportion of successful trials and (b) the first successful trial. Our results showed no direct correlation between rank and inhibitory control performance. However, inhibitory control was negatively correlated with higher out-degree in the aggressive network, suggesting that lower inhibitory control ability is correlated with the likelihood of engaging in, and winning, more aggressive interactions. Overall, our results provide evidence that both social knowledge about rank and underlying inhibitory control ability affect aggressive interactions in wild parrots.

Animals often evaluate rewards relative to prior experience rather than in absolute terms, producing phenomena such as negative incentive contrast, where a previously accepted reward is rejected after a higher-quality one. This comparative evaluation is especially important for generalist foragers like bumble bees, which make thousands of daily decisions among flowers varying in reward quality. Bumble bee colonies consist of two female castes—queens and workers—whose distinct ecologies may shape reward evaluation: queens forage alone during early colony founding, whereas workers forage collectively, distributing decision costs across the colony. We tested incentive contrast in wild queens and workers by downshifting nectar rewards from 40% to either 15% or 10% under low or high satiation. Because queens outperform workers in associative learning, we predicted they would show stronger incentive contrast. Consistent with previous work, workers were more likely to reject 15% sucrose after experiencing 40%. Contrary to our prediction, queens still showed negative incentive contrast but were more likely than workers to accept 15%, regardless of satiation. Both castes rejected 10% following 40% at similarly high rates. In a second experiment assessing absolute preferences under ad libitum feeding, queens and workers consumed similar amounts of 15%, indicating that caste differences arise specifically in comparative contexts. Together, these results suggest caste-specific decision-making shaped by the higher energetic stakes queens face, with potential consequences for the evolution of floral reward traits.

The gut microbiome plays an important role in host physiology through its contributions to nutrient assimilation and metabolism. These processes are especially critical for migratory birds, which undergo extreme seasonal shifts in energetic demands and behaviour. Yet, the role of the gut microbiome in supporting these journeys remains poorly understood. In particular, we lack information on the microbiome dynamics across the annual cycle and if these shifts are linked to key migratory traits such as migratory restlessness or fuel accumulation. To address this gap, we studied the Northern wheatear (Oenanthe oenanthe), a long-distance nocturnal migrant. We kept individuals in captivity under fully standardised environmental conditions (12:12 light regime and identical diet), thereby isolating endogenous circannual changes from external cues. Using a longitudinal sampling design, we collected faecal samples repeatedly from the same individuals across all major phases of their annual cycle: summer, autumn migration, winter, and spring migration. Microbiome composition and diversity was characterised through 16S rRNA metabarcoding, allowing us to track within-individual temporal changes in gut community structure. In parallel, we quantified individual‐level variation in two key migratory traits: (i) migratory restlessness (zugunruhe), measured under laboratory conditions, and (ii) fat accumulation, as an indicator of energetic preparation for sustained flight. By integrating behavioural and physiological data with microbiome profiles, we are able to test whether seasonal shifts in gut microbiome covaries with the onset and intensity of migratory behaviour and energy storage. Our results provide one of the first controlled longitudinal approaches of microbiome dynamics across the entire annual cycle in a migratory bird, providing new insights in our understanding of how host-microbiome interactions may contribute to the physiological flexibility required for migration.

Nutritional environments are powerful selective forces shaping life-history evolution, yet they rarely act in isolation. In agricultural ecosystems, insects encounter diets that are simultaneously novel whilst also being sources of anthropogenic toxins. How these selection pressures jointly shape adaptation remains poorly understood. Here we test how insecticide resistance alleles can have broader ecological consequences by altering how organisms exploit nutritional landscapes. Using D. melanogaster fruit-flies that differ only at a naturally occurring insecticide resistance allele, we applied a nutritional geometry framework to quantify reproductive performance of both sexes across diets spanning a wide range of protein-carbohydrate ratios, as well as caloric densities, in the presence and absence of insecticides. Strikingly, a single resistance allele shifted male and female fertility optima on the nutritional landscape, indicating altered resource allocation and nutrient-use strategies. These genotype-specific performance surfaces reveal that resistance alleles can modify ecological niche breadth independent of toxin exposure. Our findings demonstrate that the evolution of insecticide resistance may be facilitated, or even accelerated, by correlated changes in nutritional adaptation. By reshaping life-history trade-offs across diets, resistance alleles may enhance colonisation potential in human-modified environments. This work integrates evolutionary physiology, chemical ecology, and nutritional theory to highlight a previously overlooked pathway by which anthropogenic stressors can restructure ecological opportunity and population dynamics.

Appropriately responding to risk is necessary for survival. How an individual makes behavioral decisions in response to this risk is dependent on many factors, particularly the interaction between genotype, parental experience, and personal experience. Our previous work has shown that personal experience with predation risk during early life shapes how individuals respond to acute threats as adults, both behaviorally and in neural activation patterns. Here, we ask how individuals may transfer information about their experiences to their offspring and how offspring integrate this parental information with their own personal experience, especially when their experience conflicts or corroborates with that of their parents. The Amazon molly (Poecilia formosa), a naturally clonal fish species, provides a useful tool for examining how parental and personal experience are integrated, as we can control the genetic background of the individuals to pinpoint the causal effects of experience on behavior and the underlying neural mechanisms. We reared mothers that either experienced constant predator olfactory cues for the first month of their lives or mothers that experienced control conditions. Then, we split each mother’s brood into either a predation cue or control environment producing four offspring groups with each combination of maternal and personal experiences. After one month, offspring from all groups were exposed to a simulated acute threat from a model predator. We analyzed how individuals responded to this threat, both in terms of behavior and in brain neural activation patterns. These results have implications for understanding how different information sources are valued and integrated within the brain and used in behavioral responses.

The considerable energetic demands of flight strongly influence how aerial animals migrate. Migratory insects typically evolve larger flight muscles, denser mitochondria, higher oxidative enzyme activity and more efficient oxygen delivery systems. While these traits support sustained flight, they also increase baseline metabolic costs. This raises a key question: can insects that already invest heavily in aerobic performance cope with additional thermal stress under a warming climate?

The hummingbird hawkmoth Macroglossum stellatarum is one of the most evolutionarily successful lepidopteran migrants in the Palaearctic. These diurnal moths produce two to three generations per year, and, unusually for the family Sphingidae, diapause as imago. Adults forage across a broad thermal range (15-36°C), suggesting remarkable physiological plasticity. However, not all generations are likely to undertake long distance migrations, potentially leading to generation specific physiological costs. We quantified M. stellatarum resting metabolic rate across a temperature gradient using stop-flow respirometry, comparing late-season generations (potential long-distance migrants) with summer generations (short-distance migrants or residents) in Italy. Our analyses revealed several thermal breakpoints, indicating shifts in metabolic sensitivity to temperature. Preliminary results suggest thermal breakpoints at around 23°C and 31°C, with temperatures above 31°C imposing substantial physiological costs in this species. We are now comparing respiratory rates of representatives of a potentially resident population of M. stellatarum from the Azores with the main Afro-European population. We aim to highlight both the constraints and potential adaptive capacity of migratory insects facing rapid climate warming.

Research funded through the National Science Centre, Poland (grant no. 2023/51/D/NZ8/02402).

Steroid hormones play a central role in mediating life-history trade-offs through their influence on survival and reproduction. The relationship between a specific steroid and fitness has been rarely studied in nature. By analyzing 25 years of data from a free-ranging population of rock hyraxes (Procavia capensis), we show how the interaction between the sex hormone testosterone and the stress hormone cortisol is related to longevity. Among individuals with low cortisol levels, those with high testosterone lived longer than those with low testosterone. In contrast, among individuals whose cortisol levels were high, those with low testosterone lived longer than those with high testosterone. While neither longevity nor cortisol levels were heritable, testosterone levels were inherited from parents to offspring. We also found that reproductive success can be explained by an interaction between testosterone and sex. Thus, we propose that cortisol levels reflect the environmental conditions, whereas testosterone levels reflect the condition of the individual (e.g., labile qualities such as weight, social status). This suggests that stable environmental conditions, during which cortisol levels are low, are beneficial to high-testosterone individuals, which are more dominant and exhibit higher sexual and risk-taking behaviors. Conversely, under unstable environmental conditions, where cortisol levels are elevated, individuals with low testosterone levels benefit. Our findings underscore the role of endocrine mechanisms in mediating context-dependent fitness-related outcomes and highlight the importance of long-term studies in natural systems.

Reproduction is generally considered as one of the most energy-demanding processes, causing a trade-off with survival. Although this ‘cost of reproduction’ plays a pivotal role in theory on ageing and life-history evolution, the physiological mechanism driving the cost of reproduction remains largely unidentified. As mitochondria synthesize 90% of the energy available to eukaryotic cells, their efficiency may be key in mediating the cost of reproduction. In this study, we experimentally manipulated the reproductive status (gamete production) of both sexes in Japanese quail (Coturnix japonica) and tested for a causal effect of reproduction on mitochondrial respiration. We found that reproduction led to an overall increase in mitochondrial O2 consumption in females, which was primarily driven by a large increase in proton leak, as O2 consumption for ATP synthesis only increased slightly. Hence, reproductively active females had a severely reduced efficiency in ATP production, compared to non-reproductive females. We suggest that the large increase in proton leak in reproductive females may either represent an adaptive mechanism to mitigate the production of reactive oxygen species (ROS), or acts as an unavoidable consequence of elevated ATP synthesis. The latter would cause constraints on energy availability for reproductive females, and thereby cause behavioural or physiological trade-offs during reproduction. In contrast, males exhibited no detectable change in mitochondrial respiration, consistent with the lower energetic burden typically associated with male gamete production in birds. Our results provide experimental evidence that mitochondrial functioning can shift rapidly in response to reproductive state. Such changes may mediate the energetic constraints shaping reproductive strategies and the life-history trade-offs faced by females.

While the ability to sense magnetic fields is widespread across the animal kingdom, the underlying receptor responsible for this sense remains a mystery. One major factor contributing to this mystery is the lack of a simple, reproducible model system. Here, using video recordings and machine-learning–based analysis, we developed such a model by quantifying the cumulative distance and directional movement of earthworms (Eisenia fetida) in transparent soil, providing a robust and accessible system for studying magnetoreception. The use of transparent soil provided an easy way to examine the earthworms movement with automated video analysis tools.

To examine the possibility that earthworms can sense magnetic fields, we tested each individual twice on the same day: once under natural magnetic field conditions, and a second time with the magnetic field experimentally nullified to near-zero levels. We found that when individuals were tested in a nullified magnetic field, they exhibited reduced cumulative movement with no clear directional pattern, whereas under natural magnetic fields they moved nearly twice as far. These results demonstrate that earthworms can indeed sense magnetic fields, offering a compelling explanation for how they navigate underground.

More importantly, the experimental framework we established provides a robust, repeatable, and cost-effective platform for examining magnetoreception in a simple organism. This model system has the potential to serve as a crucial framework for unraveling the biological, physiological, and possibly microbial mechanisms that underpin magnetic sensing.

Flight is central to foraging, dispersal and mate search for many insects, but temperature restricts when and where they can fly. We introduce a new flight module in NicheMapR that predicts body-temperature dynamics during flight by combining metabolic heat production, convective heat transfer, radiative exchange (including emissivity), and microclimate conditions. We parameterised the model for two Australian jewel beetles that occupy contrasting thermal environments: a small species in cool climate and a large species in hot climate. Species-specific thermal limits were then used to translate predicted body temperatures into conditions enabling flight . We validated these predictions with field measurements of body temperatures and associated flight activity. We found opposing constraints on flight. In hot environments, flight is constrained by large body size, as larger beetles overheat rapidly due to high metabolic heat production interacting with elevated ambient temperatures. In cool environments, flight is constrained by small body size, because metabolic heat production is insufficient to offset rapid convective heat loss. These size-dependent limits explain observed activity patterns in the field. By linking physiology, behaviour and microclimate, our framework provides a mechanistic basis for forecasting how thermal landscapes shape insect flight, with implications for dispersal, foraging and mate search under current and future climates.

Poor nutrition and bad sleep are two modern problems. Both diet and sleep quality have fundamental effects on organisms, but at this stage only very little is known about interactive effects and their long-term implications across the lifespan. Studying fruit flies (Drosophila melanogaster), we previously found that both high protein diet and sleep disturbance (and some of their interactions) can reduce the lifespan in parents and offspring. Here, we investigate if these effects are driven by fundamental differences in metabolic traits, and measure ageing-related differences in body weight, metabolic rates, starvation resistance and locomotor behaviour under different diet (low, control, high protein) and sleep conditions (12:12 light:dark, 24-hour light). Sleep disruption is expected to influence activity as well as ageing trajectories in metabolic rates. Further, we predict strong sex-specific effects in starvation resistance and other metabolic traits (females usually being larger and high protein flies expected to be heavier in both sexes). Preliminary data suggest that sleep disruption affects female starvation resistance more strongly than males, and that parental protein content and sleep disruption regimes can affect the offsprings’ starvation resistance. For locomotor behaviour, we find that food and sleep treatments have large effects, and that there are sex differences in ageing trajectories. However, this may only affect the parental generation, as we did not detect effects of parental diet or sleep regimes on offspring activity. This study reveals that certain diets and bad sleep may act together, worsening body condition and affecting behaviour across the lifespan.

The evolutionary function of delayed implantation, a peculiarity of the reproductive cycle in more than 130 species of mammals, has long puzzled scientists. Recent work on the European roe deer (Capreolus capreolus), the only artiodactyl to exhibit delayed implantation, suggested that variation in implantation date could partly explain the observed individual differences in parturition date linked to environmental and maternal conditions. However, given the limited understanding of roe deer oestrus cycle, it remains unclear whether variation in reproductive phenology could be more strongly driven by variation in conception dates. In this work, we first developed a method to detect oestrus based on activity sensor data integrated into GPS collars, and validated this approach with data on 4 captive female roe deer. We then applied this method to activity data in 258 individuals from a wild population in south-west France (2003-2024), thus providing the first large-scale description of oestrus phenology in this species. We found that, in line with existing reports, oestrus is heavily synchronised within this population: 80% of oestrus dates fell between the 24th of July and the 7th of August. Adult females entered oestrus slightly earlier than yearlings (1.6 days, on average), which is somewhat less than the equivalent age-related difference in birth date. However, contrary to our expectations, we found no evidence of an effect of winter body mass or habitat on oestrus timing. Together, these results indicate that conception timing appears to be strongly constrained in roe deer, highlighting the likely overriding importance of the timing of delayed implantation for adjusting parturition date to environmental conditions. To our knowledge, this constitutes the first successful detection of oestrus in the wild using biologging, and advances our understanding of how delayed implantation impacts mammalian reproductive phenology.

Coexistence of species in sympatry is usually thought to be linked to a divergence in ecological niches (e.g. character displacement). One understudied axis of ecological niches is the temporal one, as individuals might be selected on their timing of activity, due to difference in resources or pressures throughout time. In my presentation, I will focus on the evolution of temporal niches at a daily scale in a community, using empirical data from neotropical butterflies of the Morpho genus. I reported the presence of differentiated temporal niches in sympatric communities, and tested what forces (abiotic and biotic) might select for divergent activity timing between individuals. I first measured at an intra and inter-specific scale whether abiotic variables such as temperature and light might constrain the temporal niche of a species. I then compared the activity timings of M.helenor across South America, and described changes based on the presence absence of its sister species M.achilles. The combination of these data, supported by theoretical models, suggests that temporal niche shifts might be driven by ecological interactions rather than abiotic constraints.

In group-living animals, open wounds pose a risk not only for the injured individual but also for the entire group, especially when the risk of infection transmission is high. To mitigate this danger, different species have developed diverse strategies – with ants representing one of the few taxa beyond humans that engage in social wound care. Yet, who provides this care and what determines its allocation remains unclear. To answer these questions, we combined controlled injury experiments with automated behavioral tracking across six colonies of the ant Camponotus fellah. Our results reveal that wound care is primarily provided by a non-specialized subset of individuals whose behavioral traits align with a transitional phase between the nurse and forager roles. Among these transitioning ants, care provision was best predicted by their prior spatial and social proximity to the injured individuals in the hours before the injury, indicating that pre-existing social affinity influences caregiving behavior. These findings offer the first empirical evidence of how caregivers are integrated into the colony’s social structure and highlight the role of social interactions in shaping the organization of wound care in ants.

Sweeting's Pond, located on Eleuthera Island in The Bahamas, is a unique, isolated marine ecosystem that contains a population of lined seahorses (Hippocampus erectus) that differ in size, shape, and animal density from other measured populations of this species. This 20-month study used photographic mark-recapture techniques to statistically estimate population parameters and examined habitat usage, morphometric changes, and movement patterns by sex in a 25X25m grid array in the south end of the pond. Seahorses were individually identified across 12 capture periods (6-102 days between captures X=51d) using visible implant fluorescent elastomer (VIFE) tags, in concert with natural and distinctive facial patterning. Additionally, recaptured individuals were measured to determine morphometrics across initial and final captures, allowing for insight into growth rates over time of this isolated population. The MARK estimated superpopulation was 495 individuals (SE=66; estimated 227 (33) males and 268 (32) females) with the probability of survival sex-dependent. However, there were 458 unique fish directly observed (182 females and 254 males), indicating differences between what we can directly observe compared to the population models based on capture histories. Thirty-three (33) males and 22 females were recaptured during the study, with males recaptured up to 4 times and females only twice. Males exhibited slightly faster daily growth rates than females, but no differences were detected in the distance moved by sex. Given the endemic nature of this population, understanding the seahorses' movement and population dynamics via long-term monitoring can provide valuable insight into their ecology and inform critical conservation management strategies.

Individual differences in behavior can influence an animal’s survival, life history and fitness among others. The degree of how such differences in foraging behavior are linked to spatial movement remains understudied. While it has been described that a generalist species tends to have a larger distribution than specialist one, it is not known whether the relationship remains the same on an individual level. Here we tested if differences between individuals in foraging behavior of the habitat generalist Small Ground Finch (Geospiza fuliginosa) and the critically endangered habitat specialist Medium Ground Finch (Camarhynchus pauper) are linked to their spatial movement. We equipped 17 male Small Ground Finches and 25 male Medium Tree Finches with Lotek 0.4g VHF transmitters using elastic leg-loops and tracked their movement for at least three non-consecutive days over five weeks during their breeding season in 2025. Whenever an individual was first resighted foraging, we recorded the foraging substrate, technique, height, diet and strata of the foraging event. We calculated the Sannon-diversity Index on an individual level and compared its relationship with spatial movement within and between species. We expect to find that individuals with a lower Diversity Index will have a larger distribution area than individuals with a high Diversity Index and that relationship will be the same for both species. Our results contribute to our understanding of how foraging behavior is linked to movement within individuals and how this relationship varies between different species. Additionally, these results can help future conservation of the Medium Tree Finch by better understanding its foraging and movement behavior.

In many migratory species, migration is not a fixed strategy. The decision-making process of whether to migrate is plastic, and the level of plasticity can vary across and even within individuals across time and environments. Importantly, these different levels of plasticity can be under varying patterns of selection, ultimately driving population dynamics. However, very few studies have quantified both across- and within-individual variation in phenotypic plasticity, particularly for migratory behaviour.

Here, we determine the plasticity of seasonal migration and how this varies among individuals using a long-term dataset on 1363 European blackbirds (Turdus merula) of a partially migrant population. Blackbirds in this study system either migrate in fall (~25% annually) or overwinter in their breeding area (~66%), but can also flexibly move shorter distances during winter (~9%). Additionally, we have access to local abiotic environmental data as well as detailed data of vegetation phenology, meaning we can quantify how ambient conditions may affect plasticity in migration.

As migration is a discrete phenotype, we use a threshold trait model to determine phenotypic plasticity of migration. This model assumes discrete phenotypes which are expressed outcomes of underlying continuous genetic and environmental effects. First, we determine sex-, age- and year-specific levels of individual plasticity in migration versus residency and how this relates to the ambient environment. Second, we estimate how plasticity within individuals changes across years. Finally, we determine how flexibility is under selection, and if the pattern of selection changes across different environmental conditions. This study highlights migratory plasticity on different levels across time and environmental change shape population-wide migration dynamics and selection on migratory tendency.

Many animals use the sun compass to guide their movement, sometimes over thousands of kilometres. Consistent use of the sun compass relies on the endogenous clock to track the sun’s arc, yet animals travelling east-west might experience mismatches between their internal clock and local time (clock-shift). Using GPS, we reveal that Manx shearwaters (Puffinus puffinus) experience such shifts during homing flights, generating predictable errors in sun compass orientation. Use of the sun compass persists even when shearwaters have access to compass-independent cues during coast-following. Our findings provide a new avenue for chronobiology research in the wild, suggest that rapid longitudinal movements may impact other processes governed by the endogenous clock, and that conserved chronobiological mechanisms impose remarkable constraints on navigation.

Seabirds are vital bio-indicators of ocean health, offering insights into marine ecosystem dynamics through their movement patterns. Modern tracking technologies like GPS tags provide rich datasets capturing their offshore movements, enabling us to study behavioral states and identify ecologically significant foraging zones. However, modeling how these movements emerge from the interaction between environmental variables (like wind, sea surface temperature, or currents) and individual variety (physiological and personal traits) remains largely to be explored. Furthermore, the simulation of diverse but realistic complete movements such as central-place foraging trips still is a major challenge in movement modelling.

Here, we introduce a generative artificial intelligence framework for simulating seabird trajectories conditioned on environmental and biological contexts. We build on advances in trajectory generation from autonomous driving and human motion modeling, adapting these architectures to capture the structure of central-place foraging in multi-species, multi-site datasets with temporal understanding. This is achieved through multi-format conditioning, including labels and environmental maps, enabling realistic and diverse movement simulations with local and global scale fidelity to observed behaviors.

This framework bridges ecological theory and machine learning by simulating the probabilistic response of seabirds to changing environmental conditions through complete individual trajectories. Beyond reconstructing realistic flight paths, the model allows hypothesis testing, scenario evaluation, and behavioral forecasting under future oceanic or climatic scenarios. Our results demonstrate that such models can enhance the predictive power of movement ecology models, improving state-of-the-art seabird trajectory simulation.

The post-fledging period is a critical stage in the life of a juvenile migrant songbird. Juveniles must develop their foraging skills, as well as the flight, navigation, and orientation skills that will allow them to make their first migration. Movement across the landscape is critical to developing all of these skills, and there is likely individual variation in the propensity to move. Testosterone is related to individual differences in migration distance in adult sparrows, but it has not been studied in the context of other movement behaviours. This study used juvenile song sparrows (Melospiza melodia) to investigate the relationships among movement propensity in a novel environment, juvenile prospecting movements, and testosterone profile. Testosterone profile is here defined as the maximal level of circulating testosterone produced in response to an injection of gonadotropin-releasing hormone (GnRH). We introduced fledged, free-living juvenile birds to an artificial chamber (2.4 x 2.4 x 1.8 m) containing 5 artificial trees, and recorded activity for 10 minutes as an index of exploration behaviour. Following this, we injected birds with GnRH to trigger a surge in circulating testosterone and collected blood samples 30 minutes post-injection. Finally, we radio-tracked birds for 2-4 weeks to assess prospecting movements. We found no relationships between individuals’ movement/exploration propensity within a novel environment and movement over the natal landscape, or with testosterone. This suggests that different juvenile movement behaviours have regulatory mechanisms that are independent of the mechanisms underlying adult migratory behaviour. Rather than having a general movement syndrome, different aspects of movement by juvenile sparrows could likely respond individually to different selective pressures.

(1) Guangxi University, University, Nanning, China - (2) Xi'an Jiaotong Liverpool University, University, suzhou, China - (3) University of Colombo, University, Colombo, Sri Lanka

Background: The conservation of tropical biodiversity will require not only protected areas, but also strategies to retain animals in degraded secondary forests and agricultural landscapes. This study aims to identify key landscape elements and habitat variables that support the movement of mixed-species bird flocks in areas outside but adjacent to rainforests in Sri Lanka.

Methods: We recorded flock movement paths in five independent sites using handheld GPS, and documented species composition, land use, and habitat variables at waypoints every 15 minutes. Land cover was assessed through high-resolution Google Earth images, and classified into land use categories based on vegetation types. To analyze habitat selection, we employed a resource selection function using generalized linear mixed models.

Results: A total of 112 flocks were observed, yielding 754 location records (average 7 ± 3 [SD] per flock) across ten independent 3-km transects over two years. Overall, a diverse array of species (total 66) were recorded in flocks. An interaction between land-use and time of day affected flock presence, but in general dense (riparian, forest patches) and moderately dense (marsh, shrubs, mixed cultivation, agroforests and rubber) vegetation was preferred throughout the day, while sparse vegetation (such as tea plantations) was avoided particularly during midday. Land-use and distance significantly affected flock composition, with the size, species richness and proportion of forest-dependent species inversely varying with distance to the forest.

Discussion and conclusion: The findings emphasize the importance of mixed cultivations, remaining forest to serve as stepping stones for flock movement outside dense forests, thereby enhancing conservation efforts in these critical landscapes are important.

Bowerbirds take their name from a structure built by the male as a stage for his courtship display: the bower. Subordinate males are tolerated by bower owners and spend years practicing the skills required for their courtship before owning a bower themselves. To date, the spatial behaviour of subordinate male bowerbirds remains poorly understood, despite its potential importance in shaping dynamics of bower acquisition and same-sex competition. In a recent published study, we used a seven year long dataset derived from GPS tracking to investigate whether resident and subordinate male spotted bowerbirds (Chlamydera maculata) differ in their movement patterns. We found that subordinate males maintain larger and less stable home ranges and visit more bowers than bower owners. Consistently with roaming behaviour, subordinates also overlapped other males’ home ranges more than bower owners did. Interestingly, resident males retained a similar site fidelity within and outside the breeding season. Contrarily to our prediction, subordinate males did not gradually reduce their ranges over years nor restricted their visitation to fewer bowers. By addressing a critical gap in our understanding of subordinate behavior, this research contributes to our understanding of alternative reproductive tactics and the development of territoriality in non-resource-based polygynous mating systems.

Combat strategies are a crucial aspect of warfare outcomes. In theory, the relative advantage of investing in two parameters, army size or individual strength, depends on battlefield complexity, which largely dictates whether armies can surround opponents, or whether fights must occur as a series of one-on-one duels. We provided empirical validation for this prediction by investigating whether environmental complexity influences battle outcomes across a range of ant species. We hypothesised that simple environments would favour large army size, whereas complex environments would favour strong individuals. Battles involved two native species (Rhytidoponera metallica, and Iridomyrmex purpureus) and two introduced species (Nylanderia cf. obscura and Linepithema humile), which varied in size and weaponry. After ranking species by individual strength, we conducted interspecific group battles in both complex and simple arenas at various ratios of strong-to-weak ants. We found that the relationship between battle outcome and arena complexity was species-specific. Complex arenas favoured individual strength and simple arenas favoured army size for four species pairs. This supports the theory that complex environments force ants to fight in a more linear fashion, allowing armies with strong individuals to perform better relative to larger, weaker, armies, whereas simple environments allow for concentrated attacks, favouring army size. However, L. humile performed better against R. metallica and I. purpureus in complex arenas, rather than simple arenas, in a trend opposite to that observed for other species. Complex environments may favour small ants, such as L. humile, because the small spaces found in them provide refugia from larger ants, allowing them to hide rather than fight. These results may provide insight into the competitive interactions between native and invasive species in urban environments, while highlighting the complex dynamics of ant battles.

Migration is a fundamental life-history stage that links development, physiology, and survival, yet its ontogeny remains poorly understood in small, long-distance migratory birds. In many species, juveniles undertake their first migration without parental guidance, raising key questions about how migratory performance changes with age and experience. Despite decades of research on avian migration, empirical data on the maiden journeys of juveniles are rare, largely due to technical constraints in tracking small-bodied species.

In this study we investigate the ontogeny of Common Swift (Apus apus) migration, comparing autumn migrations of fledglings and adults across Europe into Africa. While the migration of adult swifts has been studied using archival GPS devices, this method is unsuitable for tracking juvenile Common Swifts, as they return to breeding colonies at much lower rates and cannot reliably be recaptured. Hence, virtually nothing is known about the movements of fledglings during their first two years of life.

Using a new generation of the ICARUS-TinyFox tags, we received first real-time data on the maiden flights of fledglings and the autumn migration of adults on their way to Africa, allowing a direct comparison between the migratory performance of naïve juveniles and experienced adults.

Here we present the first migration data of young Swifts of two breeding colonies in Germany. Comparing migration patterns of juveniles and adults we further discuss our findings in the context of potential age-dependent differences in navigation, flight efficiency, and response to environmental conditions.

Orangutans build nests to rest daily by manipulating tree branches to form complex structures comprised of different components that serve different functions. Although many studies have examined the structure of the nest, literature on the exact techniques is mostly anecdotal. Using compiled footage of wild orangutans building nests, this study characterises the specific actions and materials used throughout the nest-building process. It was found that there is a significant pattern in the type of actions (df = 11, χ2 = 242.6, p < 0.001) as well as the type of materials (marked by branch diameter, df = 1, χ2 = 66.9, p < 0.001) over the course of nest building. We found a 1st phase related to constructing the nest base associated with bending/breaking (“green stick”) larger branches, followed by a 2nd phase to construct “accessories” associated with detaching/piling smaller branches. The 1st phase is observed in all sessions, while the 2nd phase was present in ~70%, suggesting a difference in necessity for the nest structure. This knowledge not only expands our understanding of orangutan cognitive abilities to construct complex structures but also supports rehabilitation efforts that need to help orphan orangutans learn this vital skill.

Offshore wind farms are emerging as critical components of renewable energy infrastructure but pose substantial risks to avian species. Meso-avoidance of wind farms are avoidance behaviours towards individual turbines. In this study, we explored the meso-avoidance of Bridled Terns (Onychoprion anaethetus) towards an offshore wind farm, using a new format of satellite tracking data: a combination of high-throughput (one-second interval trajectories) and low-throughput (one trajectory per hour) data. This combination enables a comprehensive examination of flight patterns while resolving the constraints of battery life. We used two trajectory traits, mean redirection and number of turns, to quantify meso-avoidance. We examined meso-avoidance towards obstacles surrounding a Bridled Tern breeding colony and the behavioural differences inside and outside an offshore wind farm. Our results suggest that Bridled Terns showed meso-avoidance towards wind turbines around their breeding colony. Compared to outside the wind farm, Bridled Terns had a mean redirection higher by 10.56 degrees, a number of turns higher by 0.65, and an altitude higher by 12.75 meters in the wind farm. Speed was not significantly different between the inside and outside of the wind farm. Our results provided some evidence for waterbird-friendly offshore wind farm designs where gaps between each turbine should be increased and the angular width of a wind farm formation should be decreased. The former should be implemented with consideration of forming ecological traps, and the latter should be implemented when the wind farm is near a breeding colony or directly on a migration route.

Artificial lighting at night (ALAN) from residential, commercial, transportation, and other sources has substantially altered nocturnal light environments, threatening biodiversity and ecosystem services. Insects are especially susceptible to light pollution for reasons including their maladaptive flight-to-light response. Insects attracted to lights at night experience both sublethal and lethal consequences, with direct mortality estimated at 30%. Despite this evident cost, the best mitigation approach for reducing insect phototaxis remains an open question. Here we test the effectiveness of recessing and shielding individual light sources on insect attraction in a section of the Chihuahuan Desert that experiences minimal light pollution. We deployed four light treatments (unshielded, shielded (~135 degrees), recessed (~100 degrees), and a dark control) across two seasons (spring and summer) in 2024. We sampled flying insects attracted to each light source with aerial flight intercept traps and ground-dwelling insects with pitfall traps. Recessed lighting reduced aerial insect attraction by over 50% relative to unshielded lighting, but there were no consistent differences between shielded and unshielded treatments. Furthermore, no light treatments influenced ground-dwelling insect attraction. We conclude that recessing lighting can reduce but not eliminate the flight-to-light response of insects, as orders of magnitude more insects still aggregated at recessed lights compared to dark controls. Thus, while recessing lighting can be an effective method of mitigating the negative consequences of light pollution for insect populations, additional efforts are necessary to fully conserve at-risk species and ecosystem services.

To support the reintroduction of threatened species, conservation interventions must maximise post-release survival. Recent amphibian conservation research has focused on trialling soft-release approaches using fungicide-treated artificial containers; however, systematic evaluation of how adults use artificial habitats is pivotal for strengthening in-situ conservation efforts. Water supplementation, defined as the creation or restoration of freshwater bodies, has been successfully implemented in amphibian conservation. In Costa Rica, water supplementation using ponds and plastic barrels has been applied for decades to support threatened species, including the Critically Endangered Lemur leaf frog (Agalychnis lemur). Yet, little is known about how species use these water containers, or whether adult individuals preferentially associate with one type over another. This study aimed to estimate adult male abundance and use of artificial ponds versus plastic barrels by quantifying the presence of calling adult males. Fieldwork was conducted at a private nature reserve in Costa Rica over a period of 18 months (2023 and 2024; N=40 night-surveys). In each survey, we visually inspected 29 barrels and 17 artificial ponds previously installed by the reserve owner, and recorded environmental covariates including daily precipitation, moonlight intensity and air temperature. Using presence/absence data, we fitted Royle-Nichols models to evaluate the effects of water body type and environmental conditions on adult male abundance. Results show that the estimated abundance was significantly higher in plastic barrels than artificial ponds, with barrels supporting approximately threefold more individuals. Adult male counts decreased significantly with increasing air temperature. These findings provide evidence that container type strongly influences adult habitat use and thus can inform in-situ management planning for threatened amphibians.

Carnivores are one of the most threatened groups of terrestrial mammals. This is true also for Madagascar’s carnivores, with knowledge lacking about their behavioural ecology and the effects of anthropogenic disturbances. In Maromizaha Protected Area, a primary forest in eastern of Madagascar, we conducted a first carnivore oriented camera trap survey along trails, based on sampling design defined by a spatial grid of 100m cells, and a systematic distribution of cameras across the grid in 44 sites between March and June 2025. We documented the presence of fossa (Cryptoprocta ferox), and the other 4 Malagasy carnivores’ species, the spotted fanaloka (Fossa fossana), falanouc (Eupleres goudotii), ring-tailed vontsira (Galidia elegans), broad-striped vontsira (Galidictis fasciata), as well as lemurs and other species. We applied multi-species co-occupancy models to investigate (i) the effect of environmental and anthropogenic factors on the species occupancy (ii) fossa co-occurrence with other carnivores, to investigate spatial competition, and with lemurs, to investigate spatial attraction across the landscape. Fossa and other carnivores showed lower occupancy in more open or degraded habitats, indicating sensitivity to habitat alteration, as well as in areas closer to people, while lemurs’ occupancy on trails was strongly related to forest cover as predicted and not directly influenced fossa occupancy. Co-occurrence models among fossa and other carnivores revealed weak interaction effects, suggesting spatial independence rather than spatial competitive exclusion, despite both species selecting similar habitats and occurring sympatrically. Our findings emphasize the effects of anthropogenic landscape alterations and human presence to carnivores' occupancy and the importance of natural habitats to mitigate human–carnivore conflict and develop effective conservation planning.

Hiking in nature strengthens human–nature connections, yet hikers can alter wildlife behaviour with potential cascading consequences for the ecosystem. As nature-based tourism expands, demand for new trails is rising, but most research on the impacts of trails focuses on established routes where wildlife may already be habituated or displaced. To balance conservation and recreation, it is essential to understand how animals respond when trails are first opened. We experimentally introduced new hiking trails into six previously undisturbed desert reserves and monitored medium-large mammals using 288 camera traps. In each reserve we added four 1-km trail sections surrounded by 12 cameras placed at varying distances from the trail. Sections received different daily hiker intensities for one week, allowing us to test the impacts of hiking intensity on behaviour across space and time. Species showed diverse responses. Dorcas gazelles, wild asses, and wildcats avoided areas near trails under medium-high hiking intensity, while caracals avoided the entire area. In contrast, red foxes and Indian crested porcupines increased activity near trails. Nubian ibex avoided areas near trails, whereas Arabian oryx increased activity near trails only under very low use. Most species returned to pre-disturbance spatial patterns once hikers left. We also detected shifts in diel activity. Striped hyenas, Rüppell’s foxes, and wildcats became more nocturnal under high disturbance and more diurnal under low disturbance. Cape hares, and wild asses at high intensity, shifted activity to earlier hours. Arabian wolves showed no detectable response. Overall, opening new hiking trails can substantially alter wildlife behaviour, with responses varying among species and shaped by hiker intensity and distance from trails. Minimising impacts requires clear conservation objectives and thoughtful trail planning, including buffer zones, limits on visitation, and seasonal restrictions in sensitive areas.

Island restoration projects provide valuable landscape-scale experiments to study the ecological effects of invasive predator removal. On Floreana Island, the largest ecological release in Galápagos history began with the 2023 removal of invasive mammalian predators led by the Galápagos National Park. This intervention provided an unprecedented opportunity to track long-term ecological changes in the island’s landbirds in response to shifting predator regimes. We analyse 15 years of demographic and reproductive data spanning 21 years (2004–2025) from four Darwin’s finch species, documenting shifts in finch abundance, breeding success, parasite loads, and predator pressure. Between 2004 and 2008, low rodent and Philornis downsi parasitic fly larvae abundance corresponded with high finch reproductive success. From 2010 to 2020, increased rodent predation and parasite loads led to steep declines in hatching and fledging success. Following predator removal, Darwin’s finch nest predation and parasite intensity dropped sharply. The critically endangered medium tree finch (Camarhynchus pauper) showed notable recovery, with higher pairing success, and survivorship of yearling males. These early results demonstrate promising ecological recovery, with patterns differing due to impacts of parasites and remaining predators. Ongoing monitoring is essential to understand the effects of predator removal and guide continuing restoration efforts on Floreana Island.

Biodiversity loss driven by climate change and human activities poses a critical global challenge. Population restoration and reintroduction programs are essential for mitigating this threat to endangered species, yet their outcomes often remain unpredictable due to poorly understood success factors, such as the inevitable inbreeding during bottleneck events. The conservation program of the crested ibis (Nipponia nippon) marks a successful example where the population rose from just seven individuals to over 9,000 in the past four decades. By developing an individual-based model that simulates the restoration process and incorporates species-specific demography and inbreeding data, we conclude that this successful restoration is largely deterministic, as our results closely mirror empirical recovery time and population-level inbreeding coefficients. To establish general guidelines for reintroduction programs, we compare how inbreeding depression influences the recovery success of two reintroduction strategies involving small founder populations. Our simulations reveal that the ‘firework’ approach (one-source translocations) outperforms the ‘sequential’ (serial translocations) approach in restoration effectiveness. Furthermore, by expanding analyses over a broad demographic space, we demonstrate that the net effect of inbreeding varies with species-specific demography and highlight the importance of considering their interaction when interpreting conservation outcomes and designing future reintroduction programs.

Keywords: inbreeding, demography, population restoration, reintroduction, individual-based simulation, crested ibis

When habitat loss, invasive species, or climate change hinder the reintroduction of a threatened species in its native range, extinction becomes a serious risk. One potential alternative is to introduce threatened species outside their historical range, a strategy known as conservation introduction. In such cases, quantifying how individuals disperse, settle, and interact with their novel ecosystem after release is essential to guide monitoring, anticipate potential ecological impact on resident taxa, and verify introduction success. In October 2024, nine extinct-in-the-wild sihek (Todiramphus cinnamominus) were released on Palmyra Atoll after more than 30 years of ex situ persistence, creating a rare opportunity to derive empirical post-release estimates of home range establishment of a species in a novel ecosystem. Following release, sihek movement was tracked using radio-tracking data and field observations. During the first five months post-release, one bird dispersed quickly and subsequently established residency approximately 1 km away from the release site. The remaining birds initially stayed near the release area and appeared to settle. By month three, four of these birds dispersed and had not re-established residency by February 2025, while the other four remained resident. During settled periods, mean home-range size was 8.8 ha and mean core area was 2.2 ha. By further monitoring settlement dynamics over time and testing how vegetation structure influences space use via resource selection functions, we aim to understand sihek habitat preferences and refine predictions of carrying capacity on Palmyra Atoll. Ultimately, these estimates will directly inform implementation decisions for upcoming release phases. Furthermore, they will inform quantitative models forecasting how sihek introduction may impact resident taxa, to identify potential risks and avert unanticipated negative impacts.

Gang-gang cockatoos (Callocephalon fimbriatum) are an endangered parrot species endemic to eastern Australia, yet their distribution and movement patterns remain poorly understood. This knowledge gap stems largely from practical restrictions on traditional tagging methods, limiting individual-based studies. Here, we address these limitations by developing image-based individual recognition models and applying them to citizen-science datasets. By automating individual identification, this approach provides a non-invasive tool to study the local movement ecology and population structure, ultimately supporting future conservation efforts.

We collected >20’000 photographs from two communal sleeping roosts of gang-gang cockatoos in Canberra, Australia, each consisting of 40-50 individuals. All images were manually annotated with sex, age class, and individual identity through comparison of visual features. To evaluate this approach beyond controlled field conditions, we additionally collected a citizen-science dataset with volunteers across Canberra, providing both a real-world testing dataset and preliminary data on population structure and local movement patterns.

Using deep-learning approaches, we are currently developing a convolutional neural network (CNN) pipeline capable of recognizing individual birds from these photographs. Individuals were first automatically segmented, and a validation/testing dataset was manually chosen to ensure a robust model evaluation. Current preliminary results achieve a ~50% accuracy on 20 adult individuals of the first roost. Significantly improved performance is expected as more of the dataset is incorporated and deep-learning models are optimized. Ultimately, these models will provide a foundation for future monitoring and conservation efforts of this charismatic parrot and demonstrate how we can extend the use of AI for individual recognition across more bird species.

Nest predation imposes strong selection on most bird species and invasive predators can drive birds to extinction. Understanding how nest predators find nests, and which cues make nests conspicuous helps us understand the ecological and evolutionary processes involved in these interactions as well as develop new information-based conservation strategies for vulnerable bird species. Nests and nestlings emit multiple cues, for example odour and sound, but whether different nest predators use single or multiple cues separately or together to enhance foraging efficiency remains unknown. Using information from multiple senses sequentially or simultaneously has been shown to be vital for learning about predation risk and mate recognition, but how multimodal information might influence foraging decisions is not well studied and likely to be context-dependent.

I will discuss theoretical predictions for if, and then when, predators should integrate multimodal information about prey, outlining why understanding these processes could provide new explanations for predator impacts on vulnerable birds. I will present data from two recent studies investigating cue use by wild native and introduced bird predators in Australia, the native sugar glider Petaurus breviceps and the introduced red fox Vulpes vulpes and. Understanding multimodal information use with ecologically realistic techniques has proved challenging but provides an important first step to developing multimodal sensory tactics for protecting vulnerable birds from mammalian predators.

The desert locust (Schistocerca gregaria) is a notorious plague insect. Swarms of locusts can extend over hundreds of square kilometers, posing severe threats to global food security. Yet locusts do not always swarm. Social interactions among conspecifics trigger a transition from a sedentary, cryptic ‘solitary’ lifestyle to a highly mobile, swarm-forming ‘gregarious’ phenotype. While the consequences of this transition are well described, the molecular and behavioural processes driving its initiation and regulation remain poorly understood. Here we combine controlled swarming experiments, closed-loop virtual reality (VR) and brain transcriptomics to characterise the temporal dynamics of phase change in desert locusts. We continuously monitor the behaviour of solitary locusts during their first exposure to marching bands of conspecifics, and infer social interactions by mapping mean effective forces as a function of neighbours’ relative positions and velocity. We show a clear shift in the repulsion-attraction responses of solitary animals to marching conspecifics over the first 12 hours of exposure. We then embed solitary ‘crowded’ animals into responsive, photorealistic swarms in VR. This shows that visual exposure to moving virtual conspecifics is necessary and sufficient to trigger marching behaviour in solitary animals exposed to conspecifics for longer than 24 hours. We further show that the repulsion-attraction responses of focal individuals do not qualitatively differ between real and virtual conspecifics, indicating that visual cues may suffice to recapitulate social interactions during collective motion. Lastly, we demonstrate that exposure to conspecifics is linked with significant shifts in the expression of juvenile hormone (JH) related genes. Our results provide the first continuous quantification of phase transition in desert locusts, offering direct insights into the mechanisms allowing solitary individuals to join active swarms of conspecifics.

Animals often appear to misdirect their behaviour towards incorrect or inappropriate targets. Common examples of misdirected behaviour include directing sexual behaviour towards the “wrong” targets such as members of the same sex, members of a different species, relatives, sexually immature individuals, dead individuals, or even inanimate objects. Other commonly studied behaviour that are often misdirected include aggression, foraging, egg laying, and parental care.

Misdirected behaviours are often written off as mistakes or anomalies. However, a more productive approach may be to consider that animals can benefit from employing a broad filter when deciding whether a given target should trigger a behaviour. Broad filters may be generally advantageous in many contexts as they reduce the chances of missing out on important opportunities, such as mating or foraging, that could outweigh the costs associated with occasionally misdirecting behaviour towards the “wrong” target. However, broad filters can be a double-edged sword and may be disadvantageous if misdirecting behaviour leads to significant risks, missed opportunities, and other fitness costs.

In this talk I will review recent work on how understanding the causes and consequences of misdirected behaviours allows us to build a more realistic view of animal behaviour. By explicitly considering the potential benefits of broad filters we can avoid dismissing misdirected behaviours as mere mistakes. This approach unifies different kinds of misdirected behaviour within a single framework and opens up a new suite of questions, including which factors might cause filters to become broader or narrower. Misdirected behaviour has important implications for conservation, animal welfare, and, in particular, animal responses to anthropogenic environmental change.

Mountain environments impose strong thermal constraints, including low temperatures, requiring species to adopt effective behavioural strategies for thermoregulation. Microhabitat selection plays a key role in buffering these constraints, yet remains poorly understood in many tropical systems. In the Palani Hills of the Western Ghats, we investigated how nest-site selection in the largely lowland-distributed squirrel Funambulus palmarum varies along an elevation gradient, providing insight into behavioural responses to cold conditions. We studied 221 squirrel nests across four elevation bands (lowlands–2300 m) in the Palani Hills, quantifying nest structure, host type and habitat features. To test whether nests located in colder climatic conditions provide improved thermal insulation, temperature loggers (Thermochron iButtons) were deployed to record temperature fluctuations within 25 nests, their nest microhabitats and ambient environments across different elevations. Nest-site selection varied significantly with elevation (X² = 30.06, df = 3, p < 0.001), with a strong effect size (Cramer’s V > 0.3). Specifically, the reliance on artificial substrates increased from 35% at low elevations to 80% at the highest, while tree-based nesting declined sharply. At higher elevations, nests were typically associated with shorter trees and sparser vegetation, indicating altered microhabitat selection under colder plateau conditions. One year of temperature logger data showed that nests at higher elevations exhibited greater thermal insulation and lower temperature variability than those at lower elevations. These findings highlight nest-site selection as a central behavioural mechanism through which squirrels modify their thermal environment at high elevations.

One of the most widely studied consistent individual differences in animals is boldness, commonly defined as an individual’s propensity to take risks. Boldness is typically measured from responses to novel or threatening contexts, including novel objects, novel environments, emergence, and simulated predator tests. The use of a boldness indicator has gained considerable attention in conservation behavior as it could aid translocation success and endangered species recovery. However, relationships among behaviors commonly grouped under boldness, particularly neophobia and threat-response measures, are not always straightforward, raising questions about whether a single “boldness” construct is appropriate. Given the importance of responses to novelty and predation risk in endangered species translocation programs, we investigated the structure of behavioral variation in the Attwater’s Prairie Chicken (Tympanuchus cupido attwateri). We quantified individual responses across three common behavioral assays: a novel environment/object test, a simulated predator response test, and the willingness to explore an enclosure with maze panels. Using a combination of univariate and multivariate mixed models, confirmatory factor analyses, and posterior response distributions, we evaluated nine a priori hypotheses describing relationships among 13 behavioral measures collected from 248 individuals. The best-supported model grouped activity and neophobic behaviors into a shared latent factor, while threat response and maze exploration behaviors loaded onto distinct factors. Notably, no latent factor explained behavioral variation across all three assays, nor across the novel environment/object and simulated predator tests alone. Our results indicate that a general boldness construct combining neophobia and threat response may be an inappropriate indicator for translocation decision-making, at least for Attwater’s Prairie Chickens.

Parental care is a widespread phenomenon in which parents invest in their offspring at a direct cost to themselves, which is compensated in future fitness benefits. Due to the caregiving costs, animals must decide whether to care for or abandon offspring based on ecological and social conditions. In the neotropical poison frog Allobates femoralis, males defend territories, and attract females to the territory for mating and egg deposition, and provide sole parental care. Males brood the eggs and later transport newly hatched tadpoles to small water bodies where they continue development. Although paternal care enhances offspring survival, it imposes metabolic costs and reduces a male’s opportunity to attract additional mates, particularly during tadpole transport. To avoid the cost of caring for foreign clutches, males may cannibalize clutches that are not their own. Here, we compare neuronal activation patterns underlying paternal care and cannibalism. We analysed neuronal activity using an immunohistochemistry protocol targeting pS6, a reliable neuronal activity marker. Tadpole transporting males show increased activity in regions such as the nucleus accumbens, whereas cannibalistic males exhibit activation in the ventral and lateral pallium. We also identify brain areas activated in both behavioural states. Combined, our results suggest that caregiving and filial cannibalism might be regulated by distinct neuronal circuitry. Our results reveal both shared and distinct neural activation patterns regulating caregiving and cannibalism in A. femoralis, offering insight into the mechanisms underlying context dependent parental decisions.

Aggression, a behavioural response to conspecific competition, is a ubiquitous socially responsive behaviour that modulates access to fitness-determining resources like mates, food, and territories. Aggressive behaviour and its adjustability are both theoretically predicted to have fitness costs; however, the empirical evidence is limited. Moreover, the current framework lacks an understanding of the reciprocal relationship between fitness costs and aggression: how aggression incurs costs across social contexts, and how these costs in turn shape the expression and maintenance of individual variation. To address this gap, we quantified the fitness costs (fecundity and adult lifespan) of aggression in varying social contexts (solitary, intermediate and high interactions) in Drosophila prolongata, a social and highly aggressive fruit fly species. We also manipulated ecological context via diet quality (high or low) to reveal the energetic costs of aggressive behaviour. Our results reveal that the fitness costs of aggression are not universal but arise from the interplay between ecological conditions and social experience. Under high‑quality diets, individuals gained fitness benefits when social interactions increased, whereas under low‑quality diets, fitness costs peaked at intermediate levels of social interactions. Aggressive behaviour exhibited was dependent upon both social context and conspecifics. Individuals in intermediate social contexts displayed positive responsiveness to conspecific aggression, while males in high social context displayed a de-escalating response to conspecific aggression. These behavioural differences carried fitness consequences, as individuals in intermediate social contexts exhibited substantially lower survival than those in high‑interaction contexts. Taken together, these findings reveal the multidimensional nature of aggression and underscore the need for context-specific approaches to studying social behaviour.

08 08. Movement and collective behaviour

Animal social relationships are influenced by demographic processes such as survival and recruitment. Social networks are based on both the composition of particular individuals and the pattern of their connections. Yet, how the gain and loss of individuals scales up to change community and population social structure remains poorly understood. To address this gap, we investigated the impacts of demographic turnover on social network structure over twelve winters for a migrant passerine, the golden-crowned sparrow. We found that returning sparrows showed high pairwise structural similarity between years, consistently retaining relationships with returning associates from previous years. However, the impacts of turnover of individuals between years was evident in higher-scale social structures. Social community structure was strongly influenced by demographic composition, i.e., the proportion of community members that returned, joined from a different community, or joined from outside the population. Newly immigrating birds significantly increased the internal connections of social communities, maintaining the clustered nature of connections in the population. Across the entire social network, the clustering of connections was significantly decreased in years when there was a greater proportion of returning birds. This could be attributed to the greater connections that birds successively build as they return to the winter site over multiple years. Thus, the interplay of distinct processes—social fidelity and more numerous connections among older birds and the fewer, more localized connections of newer birds—jointly drive social structures at different scales of social organization. Our results demonstrate the different effects of demographic change on social structure across pairwise, community, and population scales.

In nepotistic primates such as baboons, daughters typically attain a dominance rank near their mother, yet some females attempt to ‘buck the system’ by directing aggression at higher-ranking females, attempting rank reversals. We predicted that females would attempt more rank reversals (1) when reproductive inequality is greatest and resources are limited (i.e., when the benefits of high rank are greatest) and (2) when they are low-ranking (and therefore have much to gain) and are members of large matrilines that can provide kin-based support. Using long-term data from a wild population of baboons in Amboseli, Kenya, we used a GLMM to test our first prediction by modeling the monthly probability of attempted rank reversals as a function of rank-based differences in infant-survival (IS) and interbirth intervals (IBI), as well as environmental conditions (drought, habitat quality), measured in the 36 months prior to the attempt. To test our second prediction, we added family size and rank categories (low, middle, high) as predictor variables. In both models we included group size and observer effort as covariates. In partial support of our first prediction, females were more likely to attempt rank reversals when rank-based reproductive differences in IS or IBI were relatively great (IS: β=0.336, OR≈1.40, p = 0.001; IBI: β=0.170, OR≈1.19, p = 0.009). However, neither drought nor habitat quality predicted attempted rank reversals. In partial support of our second prediction, members of larger matrilines attempted more reversals, but they mostly targeted family members, suggesting kin support was not a deciding factor in their attempts. Notably, in most months, reproductive skew among females was low so the benefit to rank reversals was small, potentially explaining the stability of nepotistic hierarchies. Future directions include quantifying the short- and long-term consequences of rank reversals to identify whether successful rank reversals yield net fitness returns.

Menopause is characterized by a prolonged post-reproductive lifespan. It is an evolutionary puzzle and is rare among mammals, well-documented only in humans and a few toothed whale species (e.g., killer whales). Previous studies suggest that the evolution of menopause can be explained by kin selection, particularly the “grandmother hypothesis,” in which post-reproductive females increase inclusive fitness by helping their descendants. Menopause may have evolved via two evolutionary pathways: "live long" (extended lifespan with unchanged reproductive duration) or "stop early" (shortened reproductive duration). We developed an evolutionary, age- and sex-structured mathematical model that incorporates life-history, social structure, and demography to test whether a menopause-inducing allele can invade a non-menopausal population when post-reproductive females increase the survival and/or fecundity of younger kin within their social group. We parameterized the model using data from humans, chimpanzees, baboons, elephants, sperm whales, and killer whales. Our model’s predictions align with empirically observed post-reproductive representation values: it predicts menopause at empirically plausible ages only in species with menopause, under both evolutionary pathways. Consistent with prior work identifying male philopatry as a driver of increased female relatedness to the social group, we find that the selection for menopause is driven mostly by post-reproductive female help that increases male survival. We therefore propose an update to the grandmother hypothesis, which we term the “mama’s boy hypothesis”: menopause evolves when post-reproductive help increases the survival of philopatric sons and grandsons, who contribute disporportionately to maternal inclusive fitness.

Both human and non-human animals can be seen to help and benefit others, but when, how and why prosocial choices are made remains poorly understood. We address these questions with phylogenetically-controlled meta-analyses of both-benefitting, self-benefitting, other-benefitting and no-benefit decisions made by actors of 7 avian and 22 mammalian species. We examined if animals behaved prosocially in the prosocial choice test in the presence or absence of immediate benefits for actors and in the presence or absence of partners. We assessed the cooperative breeding hypothesis and the effects of different experimental designs on prosocial behavior. We conducted meta-regressions of prosocial choice test comparisons, and our meta-analyses included 299 effect sizes from 50 studies. Across species, actors appeared to first consider their own payoffs and only then their partner’s, and they benefitted their passive partners only when they themselves benefitted. Prosocial behavior was conditional on the presence of a partner in the prosocial choice test. Prosocial behavior was not affected by different experimental techniques. Species’ allomaternal care and brain size did not influence prosocial behavior, which did not support key predictions of the cooperative breeding hypothesis. With costly helping being the exception rather than rule, we conclude that prosociality in social vertebrates can evolve to the extent that individual self-interest remains preserved.

Cleaning mutualisms are among the most widely studied cooperative interactions in marine systems, with extensive work showing that cleaners’ choice of whom to clean is driven by interspecific differences among clients. Far less is known about how cleaners allocate services when multiple individuals of the same client species arrive simultaneously and seek cleaning. For the facultative cleaner Bodianus anthioides, goatfish are the most prevalent clients. Approximately 80% of goatfish visits occur in pairs or larger groups, during which they solicit parasite-removal services by assuming a characteristic “posing” posture.

We asked how cleaners allocate services among multiple conspecific clients, and whether the decision of whom to clean next is influenced by client proximity, and the number of clients present and signaling.

We recorded cleaning events involving solitary and group-arriving clients, and quantified client pose duration, waiting time prior to cleaning, order of service, and per-client cleaning duration, in order to infer cleaners’ choice of whom to serve next. We expected that increasing group size would reduce per-client cleaning duration. Contrary to this expectation, per-client cleaning duration did not differ between solitary and group contexts, and most individuals in groups were cleaned at least once. Rather than reducing service per client, group arrivals were associated with longer residence times at cleaning stations, during which clients switched posing roles and positions over time, and only a subset of individuals posed at any given moment. Cleaners’ choice was largely limited to posing clients, with proximity further affecting their choice. Together, these results show that service allocation is shaped by the interplay between cleaner decision rules and clients’ dynamic signalling and spatial behaviour, providing novel insights into how access to cooperation is structured in group contexts.

Conflicts between individuals of the same species are common in nature and are mostly resolved with limited aggression. Several theoretical studies, such as the Hawk–Dove (HD) game model, investigate the evolution of limited aggression expressed during conflicts between individuals. These studies mainly focus on the individuals involved in the conflict and their genes. Recently accumulating evidence indicates that microbes are associated with diverse functions of their host and can affect host behavior. Here we extend the classic HD game model to include both the hosts and their microbes, examining how natural selection acts on the microbes. We find that nonaggressive host behavior is more likely to evolve and spread in a population when induced by the microbes residing in the host, compared to nonaggressive behavior induced by host genes. Horizontal transmission allows microbes to colonize new hosts, making their success dependent on the fitness of both the host and its opponent. Therefore, selection on the microbes favors reduced host aggressiveness under wider conditions compared to selection acting on genes alone. Our results suggest that microbes may help explain the ubiquity of nonviolent conflict resolution. Consequently, factors that alter the microbial composition within hosts may affect the aggressiveness level in host populations.

Anthropogenic change is reshaping the environments in which animals choose mates, making it important to understand how pollutants influence the behavioural mechanisms underlying mate choice. Particularly concerning are endocrine disrupting pollutants that can make their way into the environment, such as 17α-ethinylestradiol (EE2), the active ingredient in the human contraceptive pill. In Syngnathids, male pregnancy can shift the direction and strength of mate choice, making these species powerful models for understanding how endocrine exposure interacts with mating decisions. This study tested whether a 14-day exposure to an environmentally relevant EE2 concentration (0 and 5 ng/L) alters male mate choice in the big-bellied seahorse (Hippocampus abdominalis) and, in particular, whether EE2 disrupts the known male preference for larger females. Males were given a simultaneous choice between a small and a large female, and courtship behaviour, latency to interact, and preference were quantified using BORIS, a key-logging software. Male length was also assessed to evaluate potential morphological responses to exposure. This work provides new insight into how endocrine pollution intersects with reproductive decision-making in a species with an atypical reproductive mode. Results will be discussed in the context of sexual selection and the broader ecological consequences of estrogenic contamination for mating systems.

Artificial light at night (ALAN) is a widespread pollutant that can disrupt animal behaviour and threaten species viability. Rapid land-use change is intensifying ALAN across the tropics, but regional estimates are lacking, and the sensitivity of species to ALAN in these biodiverse and threatened habitats is rarely studied. Here we report an intensification of ALAN and land-use change using satellite data from 2013 and 2021 to estimate proportions of forest disturbed by ALAN across Borneo (0.22% to 0.26%), Peninsular Malaysia (2.71% to 3.39%), and Singapore (78.5% to 91.5%). We further investigated feeding, walking, and mating activities under ALAN (relative to day and night light treatments) of three stick insect species native to these respective regions, showing that the least diurnally active (and most regionally ALAN-exposed, i.e. Singapore) species was proportionally more sensitive to ALAN via reduced activity. We then compared egg laying, incubation time, hatching success, and nymph survival across sexual and parthenogenetic origin for 5833 eggs and 11490 nymphs to show that facultative parthenogenetic viability was greatest in this species. Finally, we used matrix population modelling to suggest that this quantified parthenogenesis can comfortably offset the expected mating disruption revealed by our mapped distributions, although we caution that ALAN disruption to feeding was also evident, and effects on predatory evasion remain unknown. Taken together, our results suggest an unexpected resilience to ALAN for some facultative parthenogens, but emphasise that it can still disrupt a variety of behaviours fundamental to many species’ survival.

Climate change and urbanisation are among the most rapidly intensifying drivers of global change, yet their effects are often studied separately despite the potential for strong interactions. This study examined whether human presence modifies the effects of high temperatures on behaviour and body mass of Red-winged starlings (Onychognathus morio) in Cape Town, South Africa. The study combined historical data with data collected in 2024–2025. Body mass was measured by repeatedly weighing colour-ringed individuals on a portable electronic scale, allowing calculation of daily mass change. Behavioural observations were conducted on individually identified birds using 20-minute focal samples, during which all activities were recorded, with analyses focusing on foraging behaviour, food intake, shade seeking and panting. Temperature data were obtained from the University of Cape Town weather station, with gaps filled by calibrating data from a nearby airport weather station. Linear and generalised linear mixed-effects models were used to test the effects of temperature, human presence (weekday vs weekend), and their interaction, with individual identity included as a random factor. We found that Daily mass gain declined with increasing temperature, but only on weekends when human foot traffic was low; this effect was buffered during weekdays. On hot days, shade-seeking behaviour was more likely on weekends, and panting increased with temperature on low human presence days but not on high human presence days. Time spent foraging was influenced by temperature and day status, whereas food intake rate was unaffected. The proportion of anthropogenic food in the diet was high on weekdays (>90%), suggesting that access to high-energy urban food resources may buffer heat-related mass loss. These results indicate that urban resources can modify behavioural and physiological responses to high temperatures and may partially offset the negative effects of climate warming for birds.

Behavioral diversity is an important but understudied facet of biodiversity that enables wildlife populations to cope with rapidly changing environments. There are a growing number of studies showing that anthropogenic changes to the environment can reduce behavioral diversity in populations and species, which in turn may reduce their ability to tolerate or escape from new stressors when they arise. To understand the causes and consequences of behavioral diversity loss, we will present a conceptual framework for predicting generally expected patterns of behavioral diversity in a changed and changing world. To do so, we will begin by describing the key sources of behavioral diversity: genetic polymorphism and behavioral plasticity. We will then discuss how anthropogenic disturbances, such as habitat homogenization, reduced connectivity and the introduction of novel environments and entities, can impact behavioral diversity through the evolutionary forces of selection, flow, mutation and drift. By doing so, we will also identify and highlight important gaps in our knowledge of behavioral diversity. Understanding the mechanisms of behavioral diversity loss is essential for identifying and mitigating the specific drivers of decline, helping practitioners to conserve this variation and improve the capacity of populations to adapt and persist under future environmental change.

Animals in anthropogenic landscapes face the dual threat of disturbance from humans and predation risk from predators and hunters. However, despite increasing evidence of the impact of humans on animal behaviour, our understanding of how wildlife adapt their habitat selection to different landscapes of fear created by both humans and predators remains limited. In this context, it has been proposed that prey species may reduce the likelihood of encountering predators by selecting habitats in proximity to human infrastructure (the human shield hypothesis). Here we investigated how roe deer adapted their habitat selection during the hunting season in three study areas in the Alps (France, Slovenia and Italy) differing in large carnivore presence, hunting pressure, and anthropogenic and environmental characteristics. We built resource selection functions using GPS locations from 45 adult roe deer and fine-scale spatial data on human harvest of wild ungulates. We found support for the human shield hypothesis for roe deer in relation to harvest risk. In daytime, roe deer reduced their distance to buildings in areas where harvest risk was relatively high, whereas at night, they approached buildings in less urbanised areas, a strategy that could reduce their exposure to wild predators. We also observed significant differences in habitat selection among individuals and study areas, with the strongest response observed where wolf presence and human disturbance were the highest. Our findings demonstrate strong context-dependent variation in response to hunting and predation risk across dynamic landscapes of fear in the Alps and provide insights for long-term wildlife management in human-dominated landscapes.

Anthropogenic noise pollution levels are increasing in natural communities with numerous impacts on the behavior of animals, including recent studies demonstrating that noise negatively affects cognitive performance in birds. However, there are also examples of species thriving in urbanized habitats, suggesting that animals might overcome the challenges posed by anthropogenic noise, perhaps by habituating with repeated exposure. We examined whether zebra finches habituate to road noise when presented with continuous playback of road traffic noise versus intermittent noise playback as they learned novel foraging tasks. We hypothesized that birds exposed to continuous traffic noise during and between repeated trials would demonstrate higher cognitive performance than birds with intermittent exposure. We used a battery of foraging tasks that measured different aspects of cognition, including inhibitory control, motor learning, color association, and spatial memory. We found that birds presented with continuous noise exposure had higher performance scores in some tasks but not others. These results suggest that birds were unable to habituate broadly to the traffic playback. Instead, certain cognitive activities or modules could be more sensitive to noise-induced cognitive impairment than others, or other intrinsic factors might determine an animal’s response to distracting stimuli. Animals living with noise pollution, regardless of whether it is punctuated or continuous, could therefore experience negative cognitive impacts, with potential effects on survival or fitness.

While the wisdom of crowds – enhanced decision-making in larger groups – has been demonstrated in controlled experiments, the intractability of observing large-scale wild groups has limited evidence from natural systems. Addressing this challenge, we analyse migratory trajectories of flocks of thousands of songbirds extracted from 23 years of weather radar data across the Great Lakes region of North America. We show that the wisdom of crowds emerged in these flocks through the many-wrongs effect: by averaging out individual errors, larger flocks more accurately oriented towards their population’s migratory direction than smaller flocks. Furthermore, we observed flock size declines over time, a trend that may erode navigational performance and carry important ecological and conservation implications amid anthropogenic population fragmentation. Together, these findings reveal how the wisdom of crowds emerges in natural systems and underscore its role in shaping movement and ecological resilience in social animals.

While dispersal from the natal site to the first breeding location is ubiquitous across species, how individuals integrate environmental cues such as food availability and territory vacancy remains poorly understood. For cryptic species, in which the onset of breeding is difficult to detect due to distinct life-history traits such as delayed reproduction, inference about natal dispersal patterns is particularly vulnerable to bias arising from imperfect observation. Tawny owls (Strix aluco) inhabiting Kielder Forest, UK, provide an ideal system to address these challenges. Once established, adults typically remain faithful to a single territory throughout their lifetime, such that recruitment opportunities depend strongly on territory vacancies created by the survival of previous occupants and competition among prospective breeders. Complicating this process further, tawny owls may skip breeding while retaining a territory, depending on vole abundance, which fluctuates in pronounced 3–4-year cycles. Although all fledglings reach sexual maturity at one year of age, individuals frequently postpone their first breeding attempt until suitable environmental conditions are encountered. Using 45 years of long-term breeding data, this study develops a novel natal dispersal framework that explicitly incorporates both selected and unselected nest boxes to characterise the breeding environment experienced by each individual at the time of settlement. By accounting for alternative breeding opportunities that were available but not chosen, the approach reduces bias arising from undetected individuals and delayed recruitment. This framework aims to unravel habitat-selection processes in species capable of delaying reproduction and provides insights relevant for the management of cryptic species with complex life histories.

Nest site selection profoundly influences the fitness of many animals. For cavity-dwelling ant colonies, choosing the right nest might be particularly critical, due to their limited ability to modify nesting conditions in response to environmental changes. Yet, field studies examining ecological drivers behind nest-site selection remain limited. In this study, we investigated ecological and microclimate factors guiding nest-site selection in the rock-crevice nesting ant, Temnothorax rugatulus. Our hypothesis was that ants prefer crevice features that promote a stable microclimate and buffer against fluctuations in ambient temperature and relative humidity. By systematically measuring nest features of 679 rock crevices (79 occupied and 600 unoccupied), we first assessed whether colonies preferentially occupy rock crevices with specific features. Colonies were disproportionately found in crevices with thicker overlying exfoliation layers and surrounded by deeper leaf-litter accumulations than those of unoccupied crevices. Occupied crevices also showed a strong east-facing orientation (mean azimuth ≈ 85˚). Next, we used data loggers to monitor the temperature and relative humidity inside the nests and in the ambient environment over a full year. The data revealed a strong microclimate buffering effect by the occupied crevices. Average temperature fluctuations inside the nests were 1.5˚C lower than ambient. The peak buffering happened during the winter season. Even when ambient temperature minima dropped to -10˚C, internal nest temperatures never dropped below -4˚C. A similar pattern was observed in relative humidity, where the daily humidity swings inside the nest were reduced by 8% on average. Collectively, these results demonstrate that the nest features combine to directly enhance microclimate stability in T. rugatulus nests, potentially influencing colony fitness and ecological resilience in environments characterized by significant temperature fluctuations.

Collective decisions can generate counterintuitive group-level outcomes. We asked whether Braess’s paradox—where adding an apparently beneficial route reduces overall performance—emerges in a social fish and how its expression relates to crowding at bottlenecks. Female guppies (Poecilia reticulata) were tested in a glass-tank arena with one versus two exits under two paradigms that sample distinct motivational states: forced flow (an advancing wall compelling passage) and motivated flow (trained shoals exiting to access food). We quantified evacuation performance (throughput) and bottleneck signatures (burst sizes; inter-exit time structure).

We found that the movement's context altered the group's collective performance: the average flow rate (fish/s) was consistently higher for motivated groups than for forced groups. Across configurations, evacuations were intermittent: groups exited in bursts separated by pauses (clogs). Critically, adding a second exit did not outperform an additive baseline derived from single-exit trials and sometimes reduced throughput—consistent with Braess’s paradox. Paradox severity tracked the strength of clogging (heavier-tailed inter-exit times), suggesting that decentralised, individually reasonable choices can concentrate traffic and impede the group. We found no evidence of lateral side bias with two exits, and in the motivated paradigm food type did not alter flow, allowing us to treat it as a single “motivated” condition.

Our results provide, to our knowledge, the first experimental demonstration of Braess’s paradox in animals and link it to measurable properties of collective movement at a bottleneck. For behavioural ecology, this offers a simple rule-of-thumb: extra options help only when they separate flows. The work bridges decision rules and physical constraints, highlighting how motivation, local interactions and geometry combine to shape collective performance.

Understanding how animals integrate environmental, cognitive, and social information during movement is essential for predicting their responses to habitat change, yet empirical assessments that jointly quantify these mechanisms remain rare. We investigated how habitat structure, resource distribution, spatial memory, energetic expenditure, risk perception, and the social landscape interact to shape route planning in the Endangered black lion tamarin (BLT, Leontopithecus chrysopygus), an arboreal primate living in a 100-ha seasonal Atlantic Forest fragment. Using high-resolution GPS and accelerometer data combined with spatially explicit models of fruit availability, canopy structure, movement costs, and fine-scale vocal activity across rainy and dry seasons, we evaluated the drivers of movement decisions with integrated step-selection models. In both seasons, BLTs consistently selected taller canopies and areas with higher densities of previously known fruiting trees, revealing coordinated effects of memory and habitat features on space use. Seasonal contrasts exposed additional behavioural flexibility: rainy-season movements were constrained by energetic expenditure, whereas dry-season movements were dominated by elevated risk perception, with alarm calls prompting shorter, more tortuous paths. Long calls, used for inter-group communication, altered movement differently across seasons, indicating shifting social pressures. Together, these results show how animals dynamically combine spatial, energetic, and social cues to navigate complex landscapes, providing a mechanistic understanding of route planning with direct relevance for predicting behavioural responses to rapid environmental change.

Rank is an important determinant of fitness. Accordingly, in animal systems with fission-fusion dynamics, individuals may be expected to choose the group that allows them to achieve the highest rank. However, integrating into a new group may require increased initial conflict, which can be costly and result in serious injury or fatality. Furthermore, the benefits of joining a new group or staying with a current one may change under different environmental contexts. In risky, predator-rich environments, factors such as familiarity or kinship can improve important anti-predator responses, such as group cohesion or vigilance. Thus individuals in fission-fusion groups need to weigh the costs and benefits of groups that improve their rank versus those with better antipredator responses. We designed an experiment to test how association decisions differ between individuals with different dominance ranks across environmental contexts. Using the naturally, genetically clonal Amazon molly (Poecilia formosa), we established 45 replicate groups of four individuals allowing them to determine their dominance hierarchy. We then placed either the top or bottom ranked individuals in a binary choice assay, where they could associate with either their familiar group or a novel, unfamiliar group. We examined how these choices changed under 'risky' conditions, by introducing alarm and predator cues. We found that rank was an important driver of group preference in safe conditions, with bottom ranked fish choosing to spend more time with unfamiliar groups and top ranked fish showing no preference. Interestingly, fish showed no preference after the alarm cue was added, possibly indicating that fish were just joining any group at random. These results have implications for understanding how individual decisions lead to complex fission fusion dynamics across environmental contexts.

Stopover sites are essential refueling stations that enable migratory songbirds to restore energy during migration. Although songbird diets in breeding and wintering grounds are well characterized, their dietary preferences during stopovers remain relatively understudied. Because migration imposes extreme energetic and physiological demands, understanding diet choice at stopovers is key to revealing the behavioral strategies that enable successful migration. Furthermore, diet strongly influences gut microbiome (GM) composition and function, thus, shifts in diet along the migratory route are likely to alter GM structure, with potential consequences for survival and fitness. We examined the diet and GM dynamics in two insectivorous migrants, the Eurasian Reed Warbler (Acrocephalus scirpaceus) and Eurasian Blackcap (Sylvia atricapilla), during spring and autumn stopovers in the Hula Valley, a major wetland stopover along the Afro-Palearctic migration route. Using DNA metabarcoding of feces, we show that despite differing breeding and wintering diets, both species converged on a similar opportunistic diet at the stopover site, foraging mainly on aquatic Chironomidae (50% of diet on average). We identified over 1,200 bacterial genera, with clear differences in GM composition between bird species and across seasons. Whereas the diet shifted rapidly, the GM changed more slowly. This temporal mismatch illustrates that migrants adjust their foraging behavior immediately to local prey, while their GM responds on a much slower timescale, retaining signatures of past habitats (wintering and breeding grounds) possibly influencing digestive efficiency and overall migratory performance. The pronounced shift toward opportunistic foraging underscores the value of generalist strategies during migration, enabling birds to exploit available resources and meet the intense energetic demands of long-distance travel.

Thermal conditions can vary substantially across different habitats, enabling animals to seek out suitable environments, even at suboptimal ambient temperatures. Cool, shaded areas enable many plants and animals to cope with daytime heat, while sunny areas can provide a warmer environment in winter. Both theory and empirical studies suggest that animals should, and can, use habitat differences to effectively minimize the impact of adverse conditions. However, thermal conditions can vary at several different spatial scales, and it is unclear whether fine-scale variation maps onto variation at larger scales. Here, we quantify temperature variation across different spatiotemporal scales and substrates to capture the importance of this variation for ground-foraging superb fairywrens (Malurus cyaneus) using thermal imaging. We found both variation in temperatures among habitats but also differences in microhabitat variation among substrates (within ~900 cm2; one thermal image). Roads were warmer than natural substrates, while leaves and mulch were the most variable. Sunny areas were consistently warmer than shaded ones, and temperature variation was higher on sunny days and around midday. Our results on foraging site selection show that superb fairywrens are sensitive to this temperature variation, selecting for colder, shaded foraging spots in summer. We predict to see a reversal of this trend in winter, with birds selecting warmer foraging spots at colder ambient temperatures. Within-image variation of foraging site pictures reveals that superb fairywrens can modulate foraging site selection according to fine-scale temperature differences, potentially matching the scale at which their prey-mainly small arthropods- selects habitat. Overall, our results show how small animals navigate fine-scale temperature variations owing to changing thermoregulatory needs and highlight the importance of scale when assessing microhabitat variability.

Landscape context strongly shapes how pollinators exploit floral resources, yet its effects on the foraging behaviour of Asian honey bees remain underexplored. Understanding how landscapes influence foraging preferences and task partitioning is essential for explaining how closely related species coexist and maintain high foraging efficiency. We studied nectar preferences, sucrose responsiveness, and the division of foraging labour in three co-occurring honey bee species in southern India: Apis florea (open-nesting), Apis cerana (cavity-nesting), and Apis mellifera (introduced cavity-nesting), across forest, plantation, and urban landscapes. Landscape type strongly affected the sugar concentration of nectar collected by honey bees. All species collected high nectar concentrations in forests. While A. florea consistently collected high-concentration nectar across landscapes, A. mellifera and A. cerana foraged on more dilute nectar in plantation and urban habitats. Also, A. florea showed a unique positive relationship between nectar volume and sugar concentration, suggesting its selection for high-quality resources. Conversely, A. mellifera and A. cerana foraged on comparatively dilute nectar, suggesting volume-oriented strategies. Such species-level patterns aligned with sucrose responsiveness assays, where A. mellifera and A. cerana were more responsive to sucrose stimuli than A. florea. Foraging task allocation also strongly depended on landscape and species. While A. cerana predominantly collected nectar, A. mellifera showed balanced proportions of pollen, nectar and water foragers, and A. florea shifted task allocation across landscapes. Overall, landscape composition together with physiology and nesting biology shapes foraging preferences and the organisation of foraging labour in Asian honey bees. This study provides the first comparative understanding of how environmental context and species traits jointly structure foraging strategies across landscapes.

10 10. Conservation behaviour

Animals use a variety of environmental cues to identify profitable conditions and increase their foraging efficiency. Identifying environmental correlates of foraging behaviour can help to understand the drivers of animal foraging decisions, and the potential consequences should conditions change.

We used GPS tracking devices to collect data on movement behaviour of 42 individual European nightjars (Caprimulgus europaeus), from 2015-2018. Nightjars prey exclusively on aerial invertebrates, and to understand how they allocated their limited nocturnal foraging time, and to see if their behaviour was influenced by the lunar cycle, weather conditions, and habitat type, we analysed the environmental factors that influenced foraging within and across multiple nights.

Nightjar movement patterns analysed through Hidden Markov Models, including changes in behaviour, were primarily driven by the lunar cycle, and cloud cover, with a lesser influence from NDVI and temperature. Nightjars responded to cyclical cues most strongly, foraging more when lunar light levels were high, the moon was low in the sky, and skies were clear. Nightjars also concentrated their foraging in areas containing vegetation that provided efficient movement as well as visibility, supporting the reduced effort hypothesis.

On a night by night basis, birds foraged for more time when the moon was between 60% and 90% illuminated, but the strength of this relationship varied dependent on lunar altitude and the amount of cloud present. Birds also foraged more in areas of open vegetation compared to dense areas, as expected, based on their visual searching tactics. We suggest that this indicates a trade-off between prey availability and visibility that may reflect allocating more time to conditions that promote reduced effort and increased foraging efficiency. Limited understanding remains about the actual physiological impact of these foraging choices and knock on effect on breeding success.

As climate change intensifies, animals increasingly experience harsh environmental conditions that reshape the trade-offs underlying behavioral decision-making. A central challenge in behavioral ecology is determining whether classical theoretical frameworks, such as optimal foraging theory, remain predictive under extreme ecological stress or whether animals adopt alternative strategies when key assumptions change. We addressed this question using wild vulturine guineafowl (Acryllium vulturinum), a highly social, arid-adapted bird living in the savannas of central Kenya, sampled across a gradient of environmental harshness from drought to favorable conditions. We combined high-resolution GPS and accelerometry data with satellite-derived vegetation indices (NDVI) to quantify how behavioral state dynamics shift across environmental conditions. Using hidden Markov models, we inferred discrete behavioral states and estimated state persistence and transition probabilities as functions of environmental harshness. Our results indicate that in harsher conditions (low NDVI), guineafowl showed reduced persistence in foraging states and an increased likelihood of transitioning away from foraging, particularly into travel (movement) states. In more favorable conditions, foraging states were more persistent and transitions less frequent, consistent with classical optimal foraging expectations. These patterns suggest that while overall foraging effort may increase under drought, foraging becomes more fragmented, potentially reflecting heightened thermoregulatory or locomotor constraints not considered in optimality models. Together, our findings show that behavioral responses to environmental harshness are expressed not only in time budgets, but in the fine-scale structure of behavioral transitions, providing a framework for testing the robustness of behavioral theory under climate-driven environmental change.

Tropical ecosystems are known for their high species diversity. Different adaptations enable species to coexist and thus permit niche differentiation. Historically, research focused primarily on morphological and behavioral adaptations for foraging, roosting, and other basic ecological factors. Another important adaptation, however, is differences in sensory capabilities. So far, studies mainly have focused on behavioral strategies of predators and their prey preference to study foraging niches. Understanding the coexistence of different foraging strategies, however, requires understanding underlying cognitive and neural mechanisms. The neotropical leaf-nosed family Phyllostomidae is ecologically highly diverse, with many co-existing species. We investigated hearing niche differentiation in gleaning bats, presenting the hearing thresholds and echolocation calls of 12 different species. In our study we measured auditory brainstem responses to assess sensitivity thresholds and dynamic responses to different acoustic stimuli. The audiograms had similar overall shapes but differed in slopes and sensitivity peaks. Hearing sensitivities differed mainly in the low frequency range for frequencies below 9 kHz and in the high frequency range for frequencies of their echolocation calls. Our results suggest that differences in hearing abilities contribute to the diversity of foraging strategies of gleaning bats. We argue that differences in auditory sensitivity and hearing can be a key mechanism explaining diversity in sensory niches and coexistence of species.

Naturally selected adaptations, such as camouflage, are often thought to impair the elaboration of conspicuous sexual signals. In katydids, males produce acoustic signals using specialised sound-producing structures on their wings: a scraper on one forewing is rubbed against a file lined with cuticular teeth on the other forewing and amplified using adjacent sound radiators. These dedicated sound producing structures are found on a physically distinct area of the forewing, but in many Neotropical species, the remainder of the wing has evolved enormous, exaggerated structures that mimic vegetation to deceive and avoid predators. Here, we tested how these large, adjacent physical modifications affect the bioacoustics and attractiveness of male sexual signals. Acoustic and resonance measurements of the leaf-mimic Viadana brunneri before and after removing the leaf-like portion of the wing demonstrate that these non-sound-producing wing regions alter the spectral characteristics and sound radiation of acoustic signals. Using playback experiments we found that females prefer the calls of males with the leaf-mimicking portion of their wings intact. Thus, the function and attractiveness of intraspecific signals can be enhanced by naturally-selected adaptations for predator avoidance, contradicting the common assumption of opposing sexual and natural selection driven by mate attraction and predator avoidance.

Species that exhibit intraspecific geographic variation in mate-recognition signals provide ideal systems for investigating the factors that promote the development of reproductive barriers between diverging lineages. Poison frogs (Dendrobatidae) have been a valuable model for examining geographic variation in acoustic communication signals and their relationship with variability in visual warming signals directed to potential predators. However, substantial gaps remain in our understanding of the causes and consequences of acoustic signal variation for these and other anuran clades. In this study, we characterize the advertisement call of the poison frog Oophaga histrionica and compare its spectral and temporal features among four color morphs (populations): red, orange, yellow, and white, all occurring in the municipality of Santa Cecilia, department of Risaralda, western Colombia. We also describe the characteristics of male calling sites in each morph. Between October - December 2019 and September 2023 - June 2024, we recorded calls from 60 males (20 red, 13 orange, 12 white, and 15 yellow morphs). We found significant differences in both temporal and spectral call traits among morphs. Males of the red and orange morphs produce shorter calls with higher dominant frequencies, whereas yellow and white males emit longer calls with lower frequencies. These differences are partially explained by difference in body size among morphs. Additionally, red-morph males called from the leaf litter, while males of the other three morphs vocalized from trunks and stems up to 70 cm above the ground. Whether these differences translate into patterns of mate recognition and reproductive isolation in O. histrionica remains unknown, but we are currently conducting playback experiments to evaluate this possibility.

(1) Institute of Biology, Scientific Research Centre, Slovenian Academy of Sciences and Arts, Ljubljana, Slovenia - (2) Department of Organisms and Ecosystems Research, National Institute of Biology, Ljubljana, Slovenia

Communication is an essential prerequisite to all animal interactions, making it unsurprising that animal signals can become quite complex and are often multimodal. Traditionally, multimodal communication has been interpreted through the “redundant/backup” and “multiple messages” hypotheses. However, recent studies suggest that signal meaning may emerge from the interactions between modalities, rather than simple additive effects.

Acoustic and vibratory signals are particularly suited for such interactions, as both involve mechanical oscillations. These include airborne sound waves perceived by auditory organs and substrate-borne vibrations transmitted through solid or liquid boundaries and detected by vibrosensory organs. Despite extensive research on cricket “songs,” much less is known about their vibrational signals. Recent work on the house cricket Acheta domesticus has revealed a complex vibroacoustic courtship display involving simultaneous wing stridulation, body tremulation, and leg drumming against the substrate, with robust coupling and coordination between components. This system provides an excellent model for studying how signal components interact and how their expression may depend on male condition.

To investigate condition dependence across different parts of the male vibroacoustic signal, we compared courtship signaling in males. Specifically, we used males put on a diet after molting into adults, males subjected to dietary restriction during the nymphal stage, young and old males, energetic and exhausted males, and control males. We recorded their courtship signals using laser vibrometry, sound recordings, and video to capture all aspects of the courtship display. With this setup, we were able to show that courtship signals differed significantly between condition treatments and controls, providing new insights into the complex interplay of airborne and substrate-borne components and their function as honest signals in female choice.

Temporal organization is a key but understudied dimension of animal communication, with unclear links between rhythmic structure and ecologically relevant information. Here, we focused on wild orangutan vocalizations to investigate how great ape calls are structured by rhythmic and hierarchical temporal relations that vary with signaling context and internal state.

We examined female orangutan (Pongo abelii) alarm calls, the longest known call combinations among great apes (excluding humans). These calls exhibit recursive temporal organization, with self-embedded isochrony across three hierarchical levels. Crucially, rhythmic patterning varies with perceived threat credibility, suggesting that temporal structure contributes to the encoding of ecologically relevant information.

We also analyzed long calls of male orangutans (Pongo pygmaeus wurmbii), which exhibit stable primary isochrony. Males consistently subdivide this pulse into subordinate 1:2 and 2:1 patterns, producing a double-meter organization. These rhythmic patterns are generated through tempo modulation and alternations between voiced inhalation and exhalation. Notably, ingressive phonation occurs non-randomly and is consistent with variation in vocal arousal state. Yet, the temporal pattern is maintained even when voiced inhalation is introduced, indicating fine-grained control of the respiratory–phonatory system during long-distance signalling.

Across sexes, species and call types, orangutan vocal signals are thus organized by isochrony, hierarchical subdivision, and recursive temporal embedding, supported by respiratory control and sensitive to both external context and internal state. We argue that temporal structuring enhances signal flexibility and reliability in great ape communication and provides a comparative framework for understanding the evolution of complex vocal signalling systems.

The social complexity hypothesis predicts that vocal communication is more complex in group-living species with greater opportunities for social interaction than in solitary-living ones. Facultatively social species with fluctuating social structures provide a unique system for identifying how social factors shape vocal repertoire complexity and its ontogeny on both an intra- and interspecific level.

We study vocal development in yellow mongooses (Cynictis penicillata), as they are a socially flexible species whose individuals transition between solitary living and small family groups. The objective of this research is to understand vocal ontogeny across life-history stages, particularly in relation to social context, revealing insight into which social factors may shape vocal variation. Unlike obligately social species typically studied, yellow mongooses experience lifelong variation in social complexity such as group size, sibling composition, and interaction rates. We assess how call types emerge and whether individuals raised in more socially complex environments develop more complex vocal repertoires, integrating analyses of adult vocalisations with ontogenetic trajectories. We have observed a larger call repertoire than so far expected in yellow mongooses.Preliminary results reveal a discrete call type used across multiple contexts, call combinations, and a shift in call types across life-history stages, indicating vocal flexibility.

Our study system allows us to examine vocal developmental trajectories and offers novel insight into how fluctuating social complexity can drive the evolution and development of communication in socially flexible species.

Birdsong is a key mating trait that is crucial for intrasexual competition, mate attraction, and species recognition in many songbirds. Thus, singing a song different from the local population may have severe consequences. However, birds of the same species may sing differently due to independent evolution of songs in distant and isolated populations. Since songs are socially learned, cultural evolution may even lead to faster changes in song than genetic evolution alone. It is thus crucial to understand how songs diverge between populations across geographic scales. Identifying song differences, however, can be challenging in species with complex songs (great syllable and song repertoires) and great individual variation, where classical approaches become impractical. Therefore, we explored divergence in the highly complex song of pied flycatcher males (Ficedula hypoleuca) with a cutting-edge machine learning approach. Specifically, we trained AI classification models on subsets of songs from four locations within Sweden and from further 6 locations from Spain to Finland to investigate at which distances from our focal population songs can be classified as ‘foreign’ songs. Furthermore, we tested if male flycatchers discriminate between ‘local’ and ‘foreign’ songs. We measured the responses of 60 unpaired, territorial flycatcher males to song playback at their defended nest box to test if they responded stronger to local flycatcher songs than to songs sampled at 60, 430, and 1000 km from the local population. The combination of these two approaches sheds light on how song diverges over geographic scales and if this affects conspecific interactions. With challenges such as habitat loss and fragmentation, climate change and resulting changes in dispersal patterns, it is crucial to understand how socially learned mating traits diverge and what the consequences are for individuals and species.

Related species can vary in the extent to which individuals compete or engage in affiliative relationships with same- and opposite-sex conspecifics. For example, chacma baboons (Papio ursinus) display low levels of male-male affiliation, high reproductive skew, frequent infanticide, and a lack of enduring male-female bonds, a suite of behaviors that we term “male intolerance syndrome”. In contrast, guinea baboons (P. papio) have strong male-male bonds, weak reproductive skew, little or no infanticide, and enduring male-female bonds, a suite of behaviors that we term “male tolerance syndrome”. It remains unclear whether the traits that make up male tolerance syndromes (e.g., infanticide prevalence and male-female bonds) evolve primarily in response to one another, in response to changes in demographic conditions (e.g., birth and death rates), or in response to a combination of both. To determine how these factors drive the evolution of male tolerance syndromes, we develop a simulation model of three coevolving male traits: (i) social tolerance of and affiliation with other males, (ii) investment in infanticide, and (iii) investment in social relations with females. We find that, for a given set of demographic conditions, the same male tolerance syndrome evolves from a range of different initial social conditions, suggesting that adaptation to demographic conditions primarily drives male tolerance syndromes. Male-intolerant societies tend to arise under conditions promoting small group sizes (e.g., low birth and high death rates), whereas male-tolerant societies arise when females can express considerable mating preferences. When we also allow female social strategies to evolve in our model, male tolerance syndromes have important implications for female behavior: females only invest in bonds with males if they experience reciprocal investment. Our model sheds light on how social organization evolves and emerges from underlying demographic conditions.

Background

Nasonia is a species complex of four parasitoid wasps. N. vitripennis is cosmopolitan, while the other three species are micro-sympatric with it. This distribution can select for distinct species-specific mate recognition capabilities. However, whether Nasonia males can identify hosts with conspecific females against hosts with heterospecific females is not known.

Materials and methods

We conducted all behavioural and CHC profile studies with four Nasonia species.We investigated if Nasonia males exhibit any such ability to detect hosts with conspecific wasps by providing them with a choice of hosts with conspecific and heterospecific wasps in a cafeteria assay. Further, we studied the searching behaviour of males by developing a customised Python programme for tracking the movement of males and looked for species-specific differences. Finally, we explored the CHC profiles of parasitised hosts and adult females to test the presence of species-specific olfactory signatures that can facilitate the searching behaviour of males.

Results and Conclusions

N. vitripennis males can distinguish hosts with conspecific wasps against those parasitised by N. giraulti and N. oneida, exhibiting longer search time and distance traversed with faster search speed. We also found that N. longicornis males can distinguish hosts with conspecific wasps, but only against the hosts parasitised by N. oneida. We investigated the pairwise differences in the cuticular hydrocarbon (CHC) profiles of the parasitised hosts and adult female wasps. The results reveal that the males show this ability only when the compounds responsible for differences in adult female CHC profiles were also the key differentiators of the host CHC profiles. The comparative mate searching behaviour of males of all reported species within a genus has rarely been studied.This study makes a significant contribution to our understanding of interspecific variation of conspecific-mate searching behaviour.

Sex chromosomes play a significant role influencing the phenotypes of males and females in many organism, and the resulting sex differences may have significant impacts on ecology, life history and behaviour. One manifestation of this influence is that ZW/ZZ sex-determination systems are associated with more male-skewed adult sex ratio (ASR, proportion of males in the adult population) than XX/XY systems across tetrapods (amphibians, reptiles, birds, and mammals). Here we investigate four demographic processes that potentially generate skewed ASRs: offspring sex ratio, production, sex differences in juvenile and adult mortalities and sex different maturation. Using phylogenetic analyses of a large dataset collected from 453 wild tetrapod species from 124 families, here we show that sex differences in adult mortality is the best predictor of ASR variation, although sex differences in juvenile mortality and in maturation time also contribute to ASR skews. Sex-specific adult mortality also differs between sex determination systems with XX/XY species showing more male-skewed mortalities than ZW/ZZ species. Phylogenetic path analyses confirm an influence of sex-determination system on ASR through sex-biased adult mortalities. We call for follow-up studies to uncover the potentially complex web of associations between sex determination, population dynamics and social behaviour.

Social learning strategies such as payoff-biased learning, conformity, and prestige bias are thought to shape behavioural traditions in group-living animals, including humans. However, the evolutionary consequences of prestige bias—when learners preferentially copy individuals who are already widely copied—remain unclear .

Using analytical and simulation models of finite populations, we study role-model choice based on success and prestige bias. Success bias consistently favours higher-payoff traits and acts like directional selection. In contrast, prestige bias generates rich-get-richer dynamics analogous to genetic drift: initially common traits are more likely to spread and fix, even when neutral or mildly maladaptive. Strong prestige bias in highly social groups therefore promotes rapid cultural change and arbitrary divergence in behavioural traditions between animal groups.

Across the animal kingdom, social behaviour is an important driver of behaviour. However, the complexity of social behaviour means that the study of it may be confounded by other factors. Social network analysis often relies on associative measures which are based on spatial co-occurrence. It can be difficult, using observational data, to disentangle the role of spatial and social behaviours in generating observed social networks. In order to investigate the ways in which animals prioritise feeding or social opportunities, we experimentally manipulated the feeding behaviour of wild great tits (Parus major). We allowed only males to visit some feeders, and only females to visit others. This experiment was effective at changing feeding behaviour, and creating sex-biased feeders. Despite this, the birds' social networks and sex-based assortment were resilient to the segregation. This suggests that the sex-based social behaviour observed in wild populations of these birds is generated by social behaviour, rather than being a product of spatial or foraging behaviours. With the rare opportunity to manipulate feeding locations in a wild population, this evidence is an important step in understanding the ways in which animals are able to actively create their social environments, and the various factors which may generate observed social behaviour.

In response to mimicry by their brood parasites, host species have evolved inter-individual variation in egg phenotypes (‘egg signatures’) comprising individually distinct colours and patterns. Such diversity and complexity is adaptive: hosts benefit from high likelihood of mismatches between parasite ‘forgeries’ and host signatures. However, signature variability poses a problem when it comes to decision-making rules: different individuals might benefit from making use of different signature components when comparing eggs. To test how individuals use the colour and pattern information in their signatures, I manipulated host egg colours in the field, leaving patterns constant.

I studied a wild population of tawny-flanked prinias, which are hosts to the cuckoo finch, in Zambia. Using UV blockers, I changed the colour of one egg from each host’s own clutch. Hosts sometimes rejected their own eggs when UV blocker was applied, but never rejected eggs coated with a control treatment.

Interestingly, hosts laying eggs with less pattern information were more likely to reject eggs where colour had been manipulated using UV blockers. This may suggest that individuals possessing eggs with more pattern information prioritise this information over colour information. Alternatively, hosts with more pattern information could be constrained from using colour information because background colour is less visible on highly patterned eggs. I aim to disentangle these hypotheses using pattern analyses, along with data from similar experiments on other host species present in Zambia.

Overall, these results suggest that hosts integrate information from egg colour and pattern in different ways, even within a single species. They also highlight the importance of considering colours outside the human visible spectrum, illustrating a downside of using model eggs (which may mimic egg colours to the human eye, but are invariably made from UV-absorbent materials) in experiments with birds.

Background

Recognition abilities are essential for many host defences against parasites: they enable hosts to upregulate defences and to target them to specific parasites. Yet one of the most beguiling puzzles in brood parasitism is that many hosts fail to recognise parasitic chicks, and will feed a monstrous, huge chick that bears little resemblance to their own. The plot continues to thicken after the nestling stage. On multiple occasions, we observed the fork-tailed drongo Dicrurus adsimilis switch suddenly from feeding to attacking a nestling African cuckoo Cuculus gularis, as it fledged the nest. Drongos subsequently fed the chick again after it landed.

Materials and Methods

Based on this natural history observation, we conducted a literature review, comparative analysis, and model presentation experiment at drongo nests, which found:

Results

1) attacks on brood-parasitic fledglings have been recorded across multiple host–parasite systems, with most records featuring parasitic chicks with hawk-mimicry or other conspicuous cues in flight;

2) across brood-parasitic cuckoos, adults tend to have more hawk-mimetic features than juveniles, providing weak evidence that hawk mimicry could disadvantage juvenile cuckoos; and

3) fork-tailed drongos show general alarm responses to heterospecifics (both doves and fledgling cuckoos) flying near their nest near fledging time, but fledgling cuckoos have specific cues in flight that elicit mobbing.

Conclusions

Together, this reveals that a combination of size, plumage and shape in flight likely trigger drongo attacks. We integrate these findings across different types and taxa of parasites, to understand in general how changes in mimicry, cues and signals over a parasite’s lifecycle affect their recognition by hosts. In doing so, we aim to understand some outcomes of coevolution that seem most paradoxical.

Background:

Parasitism often alters host behaviour and physiology, with implications for social organisation and symbiosis. Strepsipterans (Xenidae) are obligate endoparasitoids of a wide range of insects, yet there are no reports on their impact on the behaviour and microbiota of the primitively eusocial wasp Polistes wattii in the Indian subcontinent.

Materials and Methods:

To observe the behaviour, field observations were conducted on the nest-free aggregation of parasitised wasps. To investigate the effect of the parasitoid on the host, we used 16S rRNA amplicon sequencing (Oxford Nanopore) to study the microbiota of unparasitised wasps, parasitised wasps, and X. gadagkari. The COI gene was used to study the phylogenetic position of the Strepsipteran parasitoid in P. wattii.

Results:

We identified a new strepsipteran species, Xenos gadagkari sp. nov., parasitising the primitively eusocial wasp Polistes wattii. Parasitised wasps failed to initiate nests and instead formed stable, nest-free aggregations in shaded habitats. Microbiota analysis showed significant variation with healthy P. wattii harbouring a microbiota resembling highly eusocial vespids, while both X. gadagkari and parasitised wasps were dominated by Wolbachia and Providencia. Interestingly, the presence of Wolbachia was found in different tissues of parasitised P. wattii but not in unparasitized wasps. This indicates that parasitism drastically changes the microbial communities of their host, making the microbiota composition similar to the microbiota of the parasitoid.

Conclusions:

Our findings reveal that X. gadagkari simultaneously manipulates host behaviour and microbiota, reshaping both ecological and social dynamics. This is the first exploration of microbiota for any primitively eusocial wasp species and any strepsipteran parasitoid associated with a hymenopteran social insect.The Polistes–Xenos association provides a new system to study coevolution and behavioural ecology of parasitism.

Urbanisation is increasing rapidly worldwide, and global urban land cover is projected to double by the end of the century. Cities are characterized by high concentrations of humans, but they also harbour high densities of urban-adapted wildlife species, such as the feral pigeon (Columba livia f. urbana). Within cities, humans and wildlife live in close proximity to each other and this close co-occurrence creates ideal conditions for pathogen circulation and increases opportunities for spillover. Despite this, pathogen transmission in urban wildlife remains poorly understood. Importantly, transmission dynamics in cities may be fundamentally different from those in non-urban habitats because restricted movements confine animals to local environments. Consequently, spatial variation in urbanisation intensity and environmental pollution, including immunotoxic contaminants, may exert a strong influence on infection risk, generating pronounced fine-scale heterogeneity in pathogen prevalence and creating potential localised areas of elevated infection risk.

In this study, we used feral pigeons and the zoonotic bacterium Chlamydia psittaci as a model system to quantify how urban landscape structure and heavy metal pollution shape infection patterns. We sampled 491 pigeons across 43 locations in the city of Antwerp (Belgium) and detected an overall C. psittaci prevalence of 29.9%. Prevalence varied strongly across the city and was highly associated with local landscape composition: prevalence was significantly lower in highly urbanised areas, while prevalence increased in locations with more natural elements. However, none of the heavy metals measured in the blood and feathers had a detectable effect on the probability of C. psittaci infection.

These findings reveal strong within-city heterogeneity in pathogen occurrence and suggest that urban landscape context, rather than environmental pollution, shapes infection patterns, highlighting the need for fine-scale surveillance

Pea aphids (Acyrthosiphon pisum) are infected at intermediate frequencies with endosymbiotic bacteria that offer their host near complete protection from specific parasitoid species at minimal cost. Variation in parasitism risk over time has been thought to explain why these symbionts have not reached fixation in the host population. However, there has been little consideration of variation in space. It is possible unprotected colonies neighbouring protected colonies experience lower parasitism pressure, as their neighbours produce few or no parasitoids. Alternatively, these colonies may see increased parasitism if parasitoids can assess protective status and target unprotected colonies. Using two parasitoid species, Praon volucre and Aphidius ervi, and their corresponding defensive symbionts, we first assessed whether parasitoids show an oviposition preference when encountering protected and unprotected hosts on the same plant. Then, using experimental foraging assays we evaluated whether parasitoids avoid ovipositing in protected aphid colonies and if unprotected colonies that neighbour protected colonies may benefit from a reduction in parasitism. We found that, when foraging, parasitoids oviposit evenly in protected and unprotected colonies and that the reduced number of parasitoids produced by protected colonies led to a significant reduction in parasitism in neighbouring, unprotected colonies. [AM1.1]Our findings indicate that the spatial ecology of defensive symbionts may have important consequences for their hosts and parasitoids.

Interspecific brood parasitism has evolved repeatedly from parental care. However, many non-avian brood-parasitic lineages have ancestors lacking parental care, leaving the foundations of brood parasitism in these lineages enigmatic. We studied the evolution of brood parasitism in Lake Tanganyika radiation of Synodontis catfishes where at least one species, the cuckoo catfish, is brood parasite of mouthbrooding cichlid fishes.

We first conducted comparative analysis using behavioural, ecological, reproductive, and developmental data from all Tanganyikan Synodontis species and found that a combination of ancestral traits (large eggs and rapid embryo development) enabled the origin of brood parasitism. Evolutionary innovations then enhanced the success of brood parasitism after it emerged. Novel traits comprise frequent production of small clutches to effectively utilize host availability, the evolution of egg mimicry to facilitate host egg adoption, and modifications to development to enhance the performance of catfish embryos in the host’s buccal cavity.

We then experimentally parasitized host cichlids with the eggs of various Synodontis species and discovered that one species, a deepwater sister species of the cuckoo catfish (S. granulosus), is presumably at an intermediate stage towards parasitism.

Interestingly, despite the distinct ecological and life history contexts of the origin of catfish brood parasitism, its evolutionary and developmental outcomes align with those of canonical avian brood parasites. This suggests that general patterns are repeated in the evolution of brood parasitism, despite disparate starting conditions.

The spider Progradungula otwayensis is one of the only remaining family members of an ancient lineage of spiders, the gradungulids, and is now restricted to a single temperate rainforest in Australia. Because of their position in the family tree of spiders, they can teach us a huge amount about the evolutionary history and ancestral traits of spiders more generally. However, due to their restricted distribution and numbers, they were only discovered by western science in 1997, and as such almost nothing is known about their ecology or behaviour. To rectify this, we located and filmed over a hundred Progradungula individuals in the wild. From this, we reveal key aspects of their behavioural ecology with direct relevance to their conservation. We also describe with video the unique dynamics of their hunting behaviour, in which prey are grabbed with large, hooked legs and then thrown into a catching web, akin to a slam-dunking basketball player. We also elucidate the sensory mechanisms behind their behaviour, showing that both vision and hearing play important roles in the ecology of these enigmatic spiders. From this, we then point to how anthropogenic pollution within these senses may threaten the conservation of these important relict animals, and suggest solutions for their protection.

University: Mainz University

Institute for Quantitative and Computational Biology

University: Mainz University

Institute for Quantitative and Computational Biology

University: Mainz University

Institute for Quantitative and Computational Biology

University: Mainz University

Institute for Quantitative and Computational Biology

University: Mainz University

Institute for Quantitative and

Recent intriguing evidence suggests that intense bouts of ivory poaching have led to a rapid, heritable increase in tusklessness amongst female African Elephants. However, while tuskless females benefit from reduced adult mortality, the X-linked, large-effect mutation underlying tusklessness is lethal when transmitted to sons. Here, I will present several mathematical models that capture this trade-off and provide precise quantitative predictions for 1) the intensity of poaching required for such an X-linked mutation to invade from rarity and 2) the equilibrium frequency of tusklessness amongst females if poaching were to continue for a prolonged period of time. The models show that poaching must be very intense for tusklessness to increase in frequency; ~50% of tusk-bearing female reproductive lifespan must be lost across the population under even the most optimistic set of assumptions. However, increases in poaching severity beyond this threshold steeply increase the frequency of tuskless females expected to be present in future populations. I will show that this exorbitant invasion threshold is driven by a deviation from Fisherian sex ratios, which exacerbates the intuitive viability cost. I shall finish by discussing the implications of the models for evolutionary rescue and the long term conservation of African Elephant populations.

11 11. Anthropogenic effects on behaviour

Tieke or North Island Saddleback (Philesturnus rufusater) were an early avian model for studying cultural evolution of song. Jenkins published his research on Saddleback song dialects in Animal Behaviour in 1978, showing how song types were innovated through copying errors and how dialect neighbourhoods formed at small spatial scales. What is less well known is that Saddleback are an outstanding conservation success story. Saddleback were once common throughout the North Island of New Zealand, but their population rapidly declined when humans introduced invasive predators. From 1908 to 1964, the total number of NI Saddleback was <1000 birds, persisting on one offshore island – a huge extinction risk. In 1964, Saddleback were the focus of New Zealand’s first planned translocation aimed at establishing a second population. Since then, Saddleback have been translocated to more than 20 locations – North Island Saddleback now number >10,000 birds. In 2004, we used the translocation history of Saddleback to again look at cultural evolution of song but at a population level – we compared song types across all 13 of the populations existing at that time. We found evidence of rapid cultural change, significant cultural divergence based on translocation histories, and evidence of both novel songs and song persistence over decades. In 2021, we examined song culture of a newly established, multi-sourced population, and found new song types innovated by first year males. Overall, Saddleback songs have become shorter across serially translocated populations with some males appearing to incorporate aspects of the simpler chatter call. Nonetheless, the diversity of song types for this species has tracked upwards, parallelling their population increases – success on both counts. Today, Saddleback have resilient and sustainable populations - in the absence of invasive predators. Here I review saddleback song culture across the now extensive range that this species occupies.

Conservation behavior uses behavioral theory to address conservation issues such as human wildlife interactions. Even when potentially positive, as desired via ecotourism, the potential for negative outcomes exists. If wildlife and people compete for resources such as space, food, and water, conflict may ensue to the detriment of both. Where the consequences of interactions involve considerable risk, for example with large herbivores and predators, understanding the benefits and costs of sympatry is vital to reducing risks and ideally enhancing benefits for all actors. For instance, human elephant interactions in sub-Saharan Africa can occur under anthropogenic conditions of ecotourism, agricultural development in elephant habitat, and climate change affecting wild and cultivated landscapes. The combination can compromise food security and survival of people and elephants. In such situations, structured decision-making can inform managers on human perceptions and a no-net-loss framework incorporating behavioral theory can guide actions to mitigate negative interactions. The simultaneous consideration of the varied stakeholders can facilitate human elephant and, more broadly, human wildlife coexistence.

Invasive freshwater fish are a major global conservation challenge and represent one of the most significant threats to Australia’s native freshwater biodiversity, altering community structure and disrupting key ecosystem processes. Conventional management of invasive freshwater fish can affect fish welfare and impact non-target species, highlighting the urgent need for targeted, species-specific approaches that enhance efficiency while minimising non-target impacts. Sensory traps, devices that exploit behavioural responses to specific sensory cues, offer a powerful framework for linking sensory ecology with species-specific control strategies. Because sensory cues play a central role in how animals perceive and interact with their environment, understanding the sensory drivers of behaviour is critical to both behavioural ecology and the development of effective, targeted management tools. However, these sensory mechanisms remain poorly understood for many invasive freshwater fishes.

Here, we investigate behavioural responses to different coloured lights in the invasive eastern mosquitofish (Gambusia holbrooki). Using a field-based, portable Y-maze, fish were captured and tested shortly after collection, minimising the influence of captivity and laboratory acclimation on behaviour. Individuals were exposed to a range of coloured LED lights, and behavioural responses including attraction, avoidance, and exploratory behaviour were quantified. Preliminary results indicate consistent aversions to specific colours, suggesting that visual cues play an important role in shaping decision-making in this species. These findings provide new insight into the sensory ecology of a highly invasive fish and demonstrate how ecologically relevant behavioural experiments can inform the development of targeted, welfare-conscious management tools in freshwater systems.

Bamboo bats (genus Tylonycteris; Family Vespertilionidae) are small insectivorous bats found in the Indo-Malayan region. They exclusively roost inside bamboo internodes with special anatomical adaptations. The Western Ghats (WG), southern India, hosts a bamboo bat, Tylonycteris pachypus aurex, that is one of the rarest bats in this region. Low-mid elevation bamboo thickets are their ideal roosting habitats, and the WG hosts 28 bamboo species, out of which five are threatened. Weevils and leaf beetles attack bamboo culms, forming cavities, which are then used by bamboo bats. However, not all such bamboo cavities are occupied by bats, and it is not known how these bats select cavities or if bats prefer some cavities over others. Hence, we investigated the effects of structural features of bamboo on roost selection of the bamboo bat T. p. aurex in the WG. We found 21 cavities from two bamboo species and three clusters with bats and measured 11 structural features of both occupied and unoccupied cavities (n=21 each). We fitted a generalised mixed effects model (GLMM) with occupancy as a binary response and the structural features as fixed effects. Culm, Cluster IDs and bamboo species were random factors. Bat occupancy was significantly explained only by cavity mouth area, corresponding to an odds ratio of 18.7, suggesting the likelihood of bat occupancy varying with the area of the cavity mouth. Our findings have direct relevance to conservation as we show that bamboo bats require cavities with a certain mouth area for roosting. This specialised roosting system and dependency on bamboo puts the bats at risk of habitat loss as unsustainable harvesting and increased demand have threatened bamboo species in the WG, causing a reduction in the bamboo forests. We provide first-hand insights into the roosting ecology of bamboo bats in India, but more studies on the roosting behaviour and spatial-temporal stability of roosts are essential to understand this interaction better.

Understanding how closely related species coexist within the same geographic area is a fundamental question in behavioural ecology. Sympatric lemurs provide an ideal model for investigating niche separation mechanisms across three main dimensions: spatial use, trophic resources, and temporal or behavioural strategies. In northeastern Madagascar, we examined the spatial distribution, feeding ecology, and behavioural patterns of Indri indri, Eulemur rubriventer, and Varecia variegata, occurring within overlapping forest habitats within the Maromizaha NPA. Our results reveal clear niche differentiation across all three dimensions. Spatially, the species exhibit interspecific habitat segregation, occupying different forest strata and microhabitats in response to environmental conditions. Trophically, dietary specialisation and plasticity reduce overlap: indris rely predominantly on leaves, whereas black-and-white ruffed lemurs and red-bellied lemurs are more frugivorous. However, even among frugivores, resource partitioning occurs through the exploitation of different fruit species, tree sizes, and relative quantities, limiting direct competition. Temporally, niche partitioning fluctuates seasonally and follows sex-specific trajectories, reflecting adaptive responses to changes in resource availability and reproductive constraints. Together, these findings demonstrate that coexistence among these sympatric lemurs is maintained through a dynamic combination of spatial segregation, dietary differentiation, time shifting and flexible behavioural strategies. Given that lemurs are among the most endangered mammalian taxa worldwide, identifying species-specific ecological requirements is essential for designing forest restoration strategies aimed at preserving primate diversity in Madagascar's rapidly declining forest ecosystems.

Evolutionary game theory has provided useful explanations for how behavioural variation can be maintained. In behavioural ‘games’, this variation can persist among individuals via frequency-dependent selection and within individuals via adaptive tactic switching. Recent simulation studies have shown that individuals using strictly fixed strategies can co-evolve with individuals employing flexible, frequency-dependent strategies. However, in biological systems, we expect individuals to differ in their degree of tactic preference, as well as their degree to which they respond to the tactic of their interacting partners (social responsiveness). In order to test whether tactic preference and social responsiveness are persistent characteristics of individual strategies, we repeatedly assayed wild house sparrows across producer-scrounger foraging games in groups of three and in groups of six. This design allowed us to test both the stability of individual foraging strategy across the two contexts, as well as the scaling of social dynamics with group size. We found that the average scrounging frequency did not increase with group size, contrary to well-known producer-scrounger model predictions. However, on average individuals were less responsive in larger groups, whereas individual differences in tactic preference were present in both contexts. Furthermore, we showed that tactic preference was strongly correlated across foraging contexts, indicating that individuals maintain similar tactic preferences across different group sizes. Together these findings provide important new insights into the dynamics of social behaviour in natural populations and advance the application of evolutionary game theory to wild systems.

Ant–plant relationships rank among the most fascinating cross-kingdom interactions. Many plants have evolved specialized structures, such as extrafloral nectaries, to attract ants, which in turn feed on the secreted nectar and provide protection to the plant. This paradigm has traditionally been considered the cornerstone of such mutualisms.

In this study, we investigated the interaction between Vicia faba, a plant bearing extrafloral nectaries, and the ant Crematogaster scutellaris through a multidisciplinary approach combining behavioural ecology, metagenomics, transcriptomics, and metabolomics. Our findings reveal a relationship far more intricate than a simple food-for-defence exchange. While resource provisioning remains a key element, it is not the sole driver of the interaction. Ants obtain sugar- and lipid-rich meals, whereas plants benefit not only from herbivore deterrence but also from reduced bacterial growth on their surfaces. Indeed, ants sterilize plant leaves, potentially lowering the risk of microbial diseases.

Moreover, the trade-off between plant growth and defence is mediated by this mutualism: gene expression patterns and physiological markers indicate that ant presence reduces the need for direct defensive investment, allowing the plant to allocate more resources to growth. A particularly striking result is the role of partner manipulation in sustaining the mutualistic relationship. We provide the first experimental evidence of a plant manipulating ant behaviour via extrafloral nectar enriched with neuroactive metabolites which enhance the ants’ effectiveness as “bodyguards.”

This study uncovers novel regulatory mechanisms underlying ant–plant interactions, which may be widespread across similar systems. It also illustrates how a certain degree of partner manipulation can contribute to the stability of mutualistic relationships.

In cooperatively breeding systems, dominant breeders may benefit from the presence of subordinate non-breeders because they enhance the mean reproductive success of the breeders. Sometimes, however, such benefits can be surprisingly hard to detect. Recently, it has been proposed that breeders might tolerate non-breeders because they reduce the variance in reproductive success of the breeders, i.e., as a bet-hedging strategy. Here, we use the clown anemonefish (Amphiprion percula), which lives in social groups composed of a breeding pair and a small number of non-breeders, to experimentally test this bet-hedging hypothesis. We show that, when dominant females lose their mate, the variance in the time taken to recommence breeding is significantly less when a non-breeder is present than when a non-breeder is absent. It is estimated that widowed females are 17,000 times more likely to face extended (one-year) wait times to recommence breeding when non-breeders are absent. Given that females can breed every lunar month, year-round, for a decade or more, this indicates that females that do not tolerate non-breeders are 17,000 times more likely to have a 10% reduction in relative fitness. Our results provide strong support for the idea that non-breeders can be tolerated as a bet-hedging strategy in cooperative breeding systems.

Background:

Schooling behaviour is a key dimension of social organisation in fishes and reflects shared ecological pressures and evolutionary history. Whether large-scale patterns of social behaviour vary across marine realms, and how such behaviours are represented in global biodiversity datasets, remains unclear.

Materials and methods:

I combined sociality scores for over 6,000 reef fish species with occurrence records from the Ocean Biodiversity Information System (OBIS). Social behaviour was summarised across marine realms and spatially aggregated into 1° grid cells. Spatial summaries and exploratory negative binomial models were used to examine associations between social behaviour, observation frequency, and data coverage.

Results:

Broad patterns of schooling behaviour were similar across marine realms, despite substantial differences in ecology and biogeographic history. In contrast, the spatial distribution of occurrence records and sociality trait coverage varied among regions. Exploratory analyses indicated associations between social behaviour and observation frequency, although disentangling behavioural detectability from sampling efforts remains challenging.

Conclusions:

These findings suggest that large-scale patterns of social behaviour are biologically consistent, but their representation in biodiversity datasets is spatially uneven. Recognising how behaviour and observation processes interact is important for interpreting macro-behavioural patterns and for the use of global occurrence data in behavioural ecology across taxa.

Many avian social groups are renowned for their dynamic structure, which may differ between seasons and life stages. Common ravens, for instance, form foraging groups that vary in size and composition during their dispersal phase. During that time, they also show large between-individual variation in vagrancy, possibly because individuals develop preferences for using particular foraging sites linked to anthropogenic food sources. We here investigated the demographic drivers of group composition of ravens exploiting the food fed to captive animals in a local wildlife park in the Austrian Alps over a time period of 15 years. We used a Cormack-Jolly-Seber capture-mark-recapture model to estimate the probability of a given individual still being in the group how often the individual is seen in the group. Preliminary results suggests that individual age, but not sex or origin (captive-release or wild), predicts individuals’ probability of being detected in the local non-breeder group. Juveniles were found to have lower resighting probability than subadults and adults which showed similar resighting probability. This is in line with the prediction of increased mortality rates in inexperienced juveniles in the first year of life. However, the fact that adult resighting probability was at the same level as subadults was unexpected, as it is the general consensus of current literature that adult ravens should leave the non-breeder groups to form territories with a partner. We discuss these results in relation to the ravens’ scavenger ecology and general fission-fusion group dynamics.

Ecological conditions can result in variation in selection pressure on mothers to produce the more helpful sex (i.e. local resource enhancement hypothesis). We tested this hypothesis with the group living pine sawflies (Hymenoptera), which rely on collective chemical defence in the larval stage. Contributing to the defence is costly for an individual, and the individual's survival is higher in groups where a larger proportion of larvae participate in the production of the defensive secretion. Our data from wild populations show that sex-ratios in larval groups can vary from all-male to all-females. However, on average sex-ratios are female-biased at the group and population levels, and larvae occur mainly in full-sib groups. To study the benefits of having females in the larval group, we quantified the fitness and cooperative behaviour of individuals in virgin produced all-male groups and sexually produced mixed sex groups under low resin (control) and high resin content (harsh environment) host plant diets (Pinus sylvestris). We also tested whether reproductive output differs between virgin and mated females. We found that cooperativeness was sex-biased: haploid male larvae contributed less to the group defence than females. Interestingly, males benefitted from the presence of their sisters, especially in harsher conditions as males grew faster on a high resin diet in mixed-sex groups in comparison to all-male groups. In addition, we found that reproductive output was higher in mated than in virgin females suggesting that mating increased fertility of females. Finally, when we tested the relative importance of sex-ratio and kin-structure in determining the individual cooperativeness, we found that a sex-ratio of the group plays more important role than kin-structure in determining the individuals’ contributions. Altogether, these results suggest that local resource enhancement together with the benefits of sexual reproduction may promote female-biased sex-ratios.

Natural selection on phenotypes is a key mechanism for evolutionary change. However, individuals can also increase their fitness through additional pathways by improving the adaptive match between their phenotype and environment. Consequently, plasticity, selection and adjustment of the environment also contribute to an individual’s phenotypic fit to its environment. Such adaptive pathways concern genetically variable traits that can (co)evolve to enhance or dampen selection on average phenotypes. However, little is known about how these adaptive traits are integrated and interactively affect fitness. We tested this in house sparrow social foraging interactions, where the environment consists of social partner’ phenotypes. Specifically, we quantified investment in producing, scrounging, activity and latency behaviours, whilst experimentally manipulating selection of social environments. We decomposed each behaviour into average phenotype, plasticity to-, and adjustment of- their social environment, and estimated their phenotypic integration with structural equation modelling. We fitted selection gradients based on foraging pay-offs to observed and average phenotypes, and integrated latent variable scores of social foraging characters. This provided strong evidence for integration of average phenotypes, plasticity and adjustment of the environment, representing continuous variation in composite social foraging strategies. These integrated strategies were under weaker selection compared to observed and average phenotypes across social foraging characters. This implies that such integrated strategies mitigate selection differentials, because individuals are adaptively responding to and/or adjusting their social environment. Our findings underline the importance of considering these multiple routes to adaptation that co-evolve as strategies, rather than simply selection on singular traits, in order to improve our understanding of phenotypic evolution.

Environmental changes including habitat fragmentation, land-use change, climatic variation, pollution, and other disruptions are having varied impacts on pollinators globally. These stressors are causing regional and global changes in insect pollinator abundance, species richness, pollination effectiveness, and distribution. Bees are important and abundant pollinators across the globe, with Australia hosting a vast diversity of species within varied climatic environments. Despite the importance of bees for pollination and ecosystem services, their behavioural responses to environmental change remain comparatively understudied. Bee cognition and behaviour are critical to pollination, as bees must navigate to foraging sites, select flowers, learn and recall floral traits, and avoid predators. The paucity of knowledge on behavioural responses to environmental changes is particularly notable for non-eusocial (e.g., solitary, semi-social) bees, compared with eusocial (highly social) species, such as European honeybees and bumblebees. Thus, we have recently focused on examining the impacts of major threats on native non-eusocial bees in Australia—a large, isolated island continent. We have found that bees are experiencing cognitive decline, reduced phototaxis (attraction to light), lower activity levels, and morphological changes as a result of urbanisation and temperature changes. We discuss our recent experiments with a focus on important behaviours and cognitive function in native non-eusocial and introduced eusocial bees. Our methods have applications for future research on the behaviour of native, non-eusocial bee species, which can be challenging to study. Our studies may also have implications for how to support and conserve understudied pollinator species under future environmental changes.

The increasing prevalence of anthropogenic noise in natural soundscapes poses a threat to wildlife by masking biologically relevant sounds, causing distraction, or acting as an aversive stimulus. Nocturnal insectivorous bats rely on sound for navigation, foraging and communication, and are therefore sensitive to the effects of noise pollution. However, most research on the impact of noise on wild bats relies on indirect measures of activity (i.e. bat passes) during foraging or commuting, and subsequently the effects of noise on behaviour at roosts remain poorly understood.

This study investigates the relationship between ambient noise and behaviour of lesser horseshoe bats (Rhinolophus hipposideros) within ten maternity roosts in North Wales (UK) exposed to varying levels of human disturbance. During April–May (pre-parturition) and July–August (post-parturition), we collected hourly focal behavioural observations from in-roost video recordings (>180 hours) alongside hourly measurements of ambient noise amplitude (dB) at each roost’s emergence point. We tested whether in-roost behaviour was predicted by time of the year (pre- vs post-parturition), the amplitude and variance of ambient noise, or environmental variables i.e. temperature and rainfall.

We found that lesser horseshoe bats spent more time alert and less time resting when noise amplitude was more variable. This effect was observed only post-parturition when young were present, suggesting that breeding stage modulates behavioural responses to noise.

Our findings indicate that in-roost behaviour is influenced more by variation in noise levels than by absolute amplitude. A potential explanation is that greater noise variability reduces habituation, particularly during pup rearing, a sensitive stage of the breeding cycle. This research represents a first step toward identifying which features of noise disturb roosting bats, facilitating evidence-based mitigation measures.

Cocaine and its metabolites are increasingly being detected in aquatic environments worldwide. While previous research has demonstrated that environmental concentrations of these neuroactive substances can affect brain function, behaviour, and energetic traits in various species, this research has exclusively been conducted under simplified laboratory conditions that fail to capture real-world complexity. As a result, how cocaine pollution affects animal behaviour and movement in the wild is not known. Here, we combine novel slow-release chemical implants with acoustic telemetry tracking to reveal how environmentally realistic levels of cocaine and its main metabolite benzoylecgonine affect movement and space use of Atlantic salmon (Salmo salar) smolts in a large natural lake (Lake Vättern, Sweden). Both cocaine and benzoylecgonine exposure increased weekly movement rates of fish in the wild, with this effect being particularly pronounced in the benzoylecgonine treatment group. Further, benzoylecgonine increased dispersal and large-scale space use within the lake relative to controls. Our results demonstrate that environmental levels of illicit substances like cocaine and its metabolites can modify animal behaviour and space use in the wild, with potential consequences for species and community ecology.

Anthropogenic pollution poses a serious threat to wildlife. Particularly concerning are endocrine-disrupting chemicals (EDCs), which can mimic or interfere with hormone signalling. Given the fundamental role of hormones in regulating immunity and reproduction, androgenic EDCs are predicted to impact immunocompetence and associated life-history trade-offs. Yet, despite their potency and environmental ubiquity, the effects of androgenic EDCs on immune function and reproductive allocation remain poorly understood. Here, we tested how exposure to the androgenic agricultural pollutant 17β-trenbolone affects immunity and reproductive investment in eastern mosquitofish (Gambusia holbrooki). Adult mosquitofish were exposed to environmentally relevant concentrations of trenbolone (control: 0 ng/L, low: 11±2.9 ng/L, high: 101±13.6 ng/L) for 45 days. Immune function was assessed using phytohaemagglutinin (PHA)-induced skin swelling, white blood cell (WBC) counts, and neutrophil–lymphocyte ratio, while male reproductive investment was quantified by sperm production. Trenbolone exposure significantly impaired immunity, reducing PHA-induced swelling by approximately 25%, decreasing total WBC counts, and increasing neutrophil–lymphocyte ratios, a biomarker of inflammation and immune response. In contrast, trenbolone exposure increased sperm number, and we found an overall negative correlation between immune response and sperm production. Our findings highlight how androgenic pollutants can simultaneously compromise immunity and alter reproductive allocation, enforcing evolutionary trade-offs that could negatively affect individual fitness and population resilience in contaminated environments.

Golden eagles (Aquila chrysaetos) in the European Alps face increasing overlaps with human recreational activities in areas essential for their nesting, foraging, and soaring. Using high-resolution GPS data from individuals tracked from fledging to three years of age, we examined how landscape, human, and social environmental features related to energy expenditure (flight) and energy gain (stationary behaviour, including resting and feeding). We assessed whether eagles preferentially used less disturbed areas when stationary compared to flying, and whether such preferences changed with age as golden eagles transition from juvenile scavenging (i.e., prolonged use of fixed carcasses) to sub-adult hunting (i.e., more flexible prey capture). Environmental variables only partially distinguished stationary from movement behaviour, indicating overlap in the conditions under which eagles fly and remain stationary. However, stationary behaviour occurred within a subset of the broader landscape used during flight. This subset was characterised by lower levels of human disturbance and became more pronounced with age, suggesting that individuals may refine spatial preferences as they mature. Within stationary locations, feeding and non-feeding behaviour could not be reliably differentiated using the variables considered. Our findings suggest that areas of relatively low disturbance may play a role in supporting stationary behaviour within heavily used alpine landscapes.

In most places where they share landscapes, wolves have been observed to overall avoid areas of human activity. These conclusions are generally drawn from large-scale studies using, at the most precise, half-hourly GPS positioning from on-board sensors. Albeit giving a solid idea of the general avoidance behavior at species level, these studies tell little of individual response mechanisms. With increasing reports of fortuitous encounters between humans and wolves, societal, ethical and management issues are being raised. Confronted with the current questioning around the variability of behavior patterns, we want to explore the individual responses of wolves, equipped with GPS and accelerometers, to encounters with humans. Here we offer a perspective in the context of anthropogenic landscapes of Scandinavia.

To this end, we use a standardized approach protocol involving a human observer passing 50 m from a free-ranging animal, and additional data from various encounter types (e.g., den checks, captures…). Leveraging large datasets of 32 Hz acceleration from captive and free-ranging wolves, we developed a bio-logging toolbox of fine-scale behavioral and energetic models able to predict individual specific behaviors (lying, galloping, sniffing...) and energy expenditure continuously at resolutions up to 1 second.

Our method allows for the inspection of encounter events in an unprecedented level of detail. We use it to study the prevalence and features of wolves' flight response, including the levels of energy engaged. We also analyze response variability across encounter types and individuals. This work lays base for further studies around context-dependent responses, correspondence between human perceptions and recorded behavior patterns, and response variability at individual, population and species levels.

Urbanisation is a major driver of rapid environmental change, exposing animals to novel stressors and reshaping the social environments in which they live. Because social behaviour is central to survival and reproduction, understanding these changes is crucial for anticipating species’ responses to increasingly urbanized landscapes. Thus, we conducted a systematic review on how urbanization influences animal social behaviour, analysing its impact on all four social systems: social organization, social structure, mating systems and care systems.

Our literature search identified 227 studies covering (i) the effects of urban stressors on social behaviour (N=170), (ii) social system responses to urban environments (N=75), and (iii) the impact of urbanisation on interspecific interactions (N=12). Overall, 92% of studies reported significant urban effects, highlighting the substantial impact urbanization can have on social systems. While animals exhibit diverse responses shaped by species-specific traits and life histories, our synthesis indicates that the rapid pace of environmental change and the combination of multiple stressors in cities often destabilise complex social groups, instead favouring loosely structured aggregations with dynamic membership. Species unable to disperse outside urban areas may experience higher encounter rates that promote social tolerance and altered selection pressures may drive alternative mating strategies. However, major taxonomic and thematic biases limit broader inference: 62% of studies focused on birds, and 85% of stressor-based studies examined anthropogenic noise, leaving large gaps regarding other taxa and stressors.

Our review reveals the profound ways urbanization is reshaping social life. This synthesis is central beyond the scope of urban ecology, providing a crucial foundation for predicting species’ responses to rapidly changing environments and for informing conservation efforts in an increasingly urbanized world.

Understanding why and how animals migrate remains a central challenge in behavioural and conservation ecology. Migration exposes birds to threats across large spatial scales, including habitat loss, infrastructure development, and light pollution, making detailed knowledge of movement pathways essential for effective conservation.

The Tasmanian Boobook (Ninox leucopsis) has long been considered sedentary, although anecdotal observations have suggested seasonal movements between Tasmania and mainland Australia. Here, we present the first empirical evidence of long-distance migration in this species using satellite-tracking, supported by genetic, morphological, and occurrence data. Our findings reveal that the Tasmanian Boobook is the only known migratory owl in Australasia.

We document migration routes, timing, and staging behaviour, and identify patterns of habitat use following migration, providing new insight into the ecological drivers of movement in this species. Importantly, our results highlight potential conservation risks associated with increasing anthropogenic pressures along their Bass Strait flyway, including light pollution and offshore infrastructure. Characterising these threats is critical not only for the conservation of the Tasmanian Boobook, but also for other migratory taxa that rely on this key southern hemisphere flyway, including the Critically Endangered orange-bellied parrot. These findings challenge long-held assumptions about movement strategies across southern Australia, and identify a new focus for conservation priorities in the region.

Silk production is a unique trait of spiders, with silk extruded through spigots on the spinnerets, which are paired appendages at the end of the abdomen. Early studies showed that spinnerets have a complex musclature allowing precise control over silk construction. Notably, muscles in the anterior lateral spinnerets may control silk flow from the major ampullate gland. In orb-weaving spiders, three muscles linked to a valve-like structure have been described in this duct. This feature may allow spiders to stabilise themselves during abseiling or adjust silk stiffness by modifying shear forces during spinning. However, it was uncertain if this apparatus was exclusive to orb-weavers or present in all spiders.

To investigate, a comparative anatomical study using micro-computed tomography (µCT) was conducted. The results revealed varied configurations of possible silk-controlling muscles among spider groups. Early-branching Mygalomorphae lack these muscles, but most araneomorph (‘modern’) spiders have at least one of them, except certain families like Pholcidae, Oecobiidae, and Hersiliidae. The most complex set-up, with three muscles and a duct valve, was found in Deinopidae, some Uloboridae, and all studied Araneoidea except Linyphiidae. Sparassidae also have three muscles, though it is unclear if they possess a valve-like structure as well. These findings suggest multiple independent gains or losses of these muscles.

Ongoing research aims to determine whether differences in the silk flow control system affect function and efficiency. Understanding these variations is crucial for revealing how spiders from different evolutionary backgrounds utilise thier silk and adapt its mechanical properties to their ecological needs.

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Effects of Artificial Light and Flow on European Glass Eel (Anguilla anguilla) Movement Behaviour and Passage Success

Benjamin BLUCK (1)

(1) International Centre for Ecohydraulics Research, University of Southampton, Southampton, United Kingdom

Anguillid eels are predominantly crepuscular and nocturnal, and considered negatively phototactic. However, this phototaxis can vary in both kind and degree by species and lifestage. As a result, there is potential for humans to inadvertently impact important aspects of eel behaviour, for example impeding or delaying movement at river infrastructure that creates unnatural light gradients. Conversely, how eels respond to light could be exploited by humans, for example lamping, the use of light to attract animals, remains a widely used method of eel fishing. To better inform eel conservation and management we need to understand how artificial light affects various aspects of eel behaviour, including movement behaviour as studied here. We initially investigated behavioural response of critically endangered European glass eel (Anguilla anguilla) to light in a still-water tank, where eel passed from a light or dark start zone through a light gradient to an oppositely lit zone. Here we found that glass eel display a general aversion to light, and engage in more erratic movement behaviour in the presence of light. However, the brightness of the light used (measured in lux) had little to no effect on eel behaviour. We then studied glass eel passage success and movement behaviour through a lit and/or covered treatment zone within a recirculating flume, where flow was present so that the eel were swimming upstream as in the wild during this migratory lifestage. Results from this second study will be combined with, and compared to, the first to explore the potential impacts of artificial light and infrastructure on eel movement and migration success, and the potential mitigating factor of flow as a driver of eel movement. Further research is needed to better understand these behaviours within a more applied context, e.g. in the field, in order to help inform methods of mitigating the potential impacts of artificial light and infrastructure on glass eel populations.

Birds that migrate long distances have to overcome geographical barriers, expend high amounts of energy and time to reach regions that offer favourable conditions. In the recent decades, anthropogenic factors have heavily impacted bird migration patterns. Some species respond to it by shortening their migrating distance and overwintering closer to breeding grounds. This behavior, known as shortstopping, is highly influenced by global warming and availability of predictable anthropogenic food sources such as landfills. Artificial food sources are highly advantageous, especially for migrating birds as this provides them energy-rich food with low foraging effort. Studies in social migrants have shown that groups with older individuals have a higher tendency to shorten migrating distance.

The European white stork (Ciconia ciconia) is a large soaring bird that breeds in Europe and winters in sub-Saharan Africa. Studies in the past decade have shown stork populations breeding in western Europe shorten their migration distance or turn to residency in southern Europe. In this study, we investigate how age influences shortstopping behaviour in white storks breeding in south western Germany using GPS data from 59 white storks tagged between 2013-25 with atleast 2 complete migrations. We found that storks that overwinter beyond the Strait of Gibraltar in their first year end up shortstopping in the Iberian peninsula in later years. Furthermore, they prefer to establish new wintering ranges at previously used stopover sites. In contrast, storks overwintering in the Iberian peninsula in their first year stay faithful to these ranges over time. With age, they tend to specialise in using landfills more than shortstopping storks do. We suggest that while a high proportion of storks shortstop later in life, staying faithful to closer wintering sites is a more advantageous strategy. As this is an ongoing study, we intend to offer a more in-depth discussion at the conference.

09 09. Foraging

Understanding how animals acquire and use information from the environment is critical for linking movement to species distributions and conservation. Advances in tracking technologies and growing interest in learning processes have opened opportunities to study behaviours such as habitat exploration in translocated animals or ontogeny of migration and dispersal movements. However, accessible statistical methods are lacking. We present a learning-explicit step-selection analysis (SSA) that integrates movement, habitat selection, and learning into a single evolving process. At the start of the movement trajectory, the animal is assumed to have no knowledge of the landscape, i.e. its internal habitat quality map is initialized to zero. As the animal moves, this map is updated dynamically: with each step, only the habitat within its perceptual range becomes known and contributes to future decisions. Through simulations, we show that this method separates true habitat preferences from learning effects and reveals when large-scale behaviours, such as attraction to resources or avoidance of risks, emerge as knowledge accumulates. Critically, we demonstrate that ignoring learning, as in traditional SSA, can bias estimates of habitat selection. We conclude by discussing methodological considerations and future directions for integrating learning into movement ecology. By explicitly modelling the formation of memory that integrates both spatial information and habitat quality, our approach advances process-based movement ecology while remaining compatible with standard SSA workflows, offering practical tools for both theoretical research and applied wildlife management.

Many social groups spread out over vast territories, yet still need to come together to defend common resources. Long-distance vocalizations have the potential to facilitate collective action by forging links between dispersed group members, forming a dynamic communication network over which information can be transmitted, propagated, and acted upon. Understanding whether and how these networks function over large spatial scales has remained mostly out of reach, due to the limits of on-the-ground field observation. We deployed multi-sensor tracking collars on most members of a wild spotted hyena social group (Crocuta crocuta) in the Masai Mara, Kenya, to observe the movements and vocalizations of this spatially dispersed group simultaneously. We identified long-distance recruitment calls using collar-recorded audio data, and confirmed caller identity using throat vibrations detected via accelerometers. These recruitment calls are thought to facilitate meetups and catalyze collective responses to threats, including lions and neighboring groups. We found that hyenas responded to their groupmates’ calls over a range of 4-5 km, not only by moving rapidly toward the source, but also often by producing calls of their own, amplifying signals across the group. Hyenas were also more likely to respond when they heard multiple callers. Through agent-based models, we show that such vocal responses enhance signal spread and increase the number of individuals recruited for collective action. We argue that such long-distance communication networks can allow dispersed groups to effectively operate at multiple spatial scales: reducing local competition while retaining global connectivity for rapid recruitment. Our findings suggest that even widely separated individuals can function as a cohesive social unit when it comes to collective action, with broad implications for the evolution of fission-fusion dynamics across animal societies.

Reaping the benefits of group living depends on group members remaining cohesive, which requires making collective decisions about when and where to move. It is now well established that decision-making in most species is shared, meaning that all group members can contribute to collective actions. However, these patterns have only been studied in species that live in unilevel societies, such as where individuals make decisions with the members of their long-term social units. There still remain a significant knowledge gap in how individuals make decisions in species that live in multilevel societies (MLSs). MLSs typically involve associations among social units, which adds a complexity to decision-making as collective movements involve both long-term and temporary associates. Here, we quantify how superb fairywrens (Malurus cyaneus) make collective decisions when they make cohesive multi-unit movements. Based on 1,215 movement initiations from 92 individuals, we found that female initiators were more likely to recruit at least one follower. In multi-unit movements, individuals preferentially followed initiators from their own unit, and individuals from different units joined later than same-unit members. However, decision-making was shared among units (all units were equally able to successfully initiate collective movements). Overall, our results show that collective decision-making in multilevel societies is structured hierarchically, whereby within-group leadership (superb fairywrens move with their core social unit) drives higher-level collective outcomes (movements involving multiple social units). By linking individual traits and MLSs to group movement, our study provides novel insights into leadership patterns in complex animal societies.

Avian migration is an important transport process involving billions of birds, with individuals facing both natural challenges and growing anthropogenic pressures. Effective monitoring is essential for understanding migration dynamics and guiding conservation actions. Situated within a major flyway, Israel offers a key opportunity to study the large-scale movements of migrating birds. Passive acoustic monitoring (PAM) is emerging as a powerful and cost-effective tool for long-term ecological research. By detecting and classifying nocturnal flight calls of migrating birds, PAM provides critical insights into species composition, migration timing, and its intensity. Importantly, this method enables identification to the species level – a major challenge for other large-scale methods.

Here, we present results from continuous monitoring in southern Israel during fall 2024 and spring 2025, processed using a deep-learning-based framework for species detection and classification. A retrained BirdNET model was applied to identify nocturnal flight calls of 35 common migratory species, achieving an average recall of 0.94 and precision of 0.96 on test data. The acoustic detections revealed clear seasonal differences: fall migration showed higher call rates and greater species diversity, whereas spring migration exhibited a weaker signal and lower species diversity. Nightly vocal activity also differed between seasons—detections in fall are spread throughout the night, while in spring they concentrate near dawn, possibly reflecting birds descending after crossing arid regions to the south. This data aligned closely with visual observations from eBird, validating the method’s accuracy.

Together, these results provide a comprehensive view of songbird migration in Israel and demonstrate that PAM is a robust and scalable approach for quantifying nocturnal bird migration, characterizing species phenology, and enhancing long-term monitoring and conservation across migratory flyways.

Mesopredators need to balance the conflicting demands of obtaining resources while remaining safe as they navigate landscapes with dominant predators. Fear generalisation predicts that animals have consistent behavioural traits that govern their responses to ecologically similar risks. We tested this prediction by measuring the behavioural responses and personality traits of an invasive mesopredator, the stoat (Mustela erminea), when it encountered a dominant predator (ferret, Mustela putorius) while foraging in a captive study.

Stoats exhibited two consistent individual strategies when foraging under predation risk. Individuals that were bold, active, and exploratory approached the risky food patches with the predator quickly, initiated feeding sooner, and visited patches more frequently. In contrast, individuals that were shy and less active mitigated risk by adjusting their foraging behaviour as they delayed approaching the risky food patch and increased vigilance. The presence of a dominant predator induced strong overall shifts in stoat foraging behaviours, as stoats generally took longer to approach and visited risky patches less often, reduced time spent feeding, and increasing vigilance when close to the dominant predator. Personality effects were most evident under predator risk, indicating that individual traits shape not only whether stoats forage in high-risk areas, but also how they manage the risks while foraging.

Our results provide insights into the behavioural mechanisms through which dominant predators can structure mesopredator foraging behaviour and highlight the importance of individual variation in shaping predator–predator interactions.

Numerous species are experiencing range shifts in response to environmental change, but why some successfully track their niche while others do not remains unclear. One key process is spatial sorting of expansion-facilitating traits, which increase in frequency at the expanding range front. Sorting of behavioural traits may be especially important for philopatric species that have low dispersal rates in equilibrium populations – more dispersive individuals are expected to be the ones reaching new areas and high aggression can bring advantages in competition over resources. While the advantage of these traits is expected to decline after initial colonisation, whether spatial sorting leaves detectable behavioural gradients across the range has rarely been investigated. Here we tested whether clines in expansion-facilitating behaviours persist across the European breeding range of the reed warbler (Acrocephalus scirpaceus), a philopatric long-distance migrant that has undergone a rapid northward range expansion in the past 150 years. Exploratory behaviour was measured using a standardised open field test, combined with repeatable measures of aggression and breath rate as a proxy for stress (n = 285 individuals). To disentangle patterns caused by range expansion from other drivers of behavioural variation, such as climate (cf. Bergmann’s rule of body size increasing in colder climates), we extended the sampling beyond areas involved in the recent range expansion, tested for relationships with morphological variables and sex, and quantified ongoing fitness effects of the behavioural traits at the Finnish range edge across multiple years. We found persistent clines in typical expansion-facilitating behaviours, providing new insights into the mechanisms underpinning successful range expansions.

15 15. Behavioural genetics/genomics

There is only one species of forest rodent in Ireland, the native wood mouse (Apodemus sylvaticus). For a century, continental bank voles (Myodes glareolus) are invading hedges and forest patches, displacing native wood mice. We tested animal personality traits of individual rodents of both species at multiple sites in three invasion-related zones: established range of bank voles, expansion edge of bank voles, pre-invasion. The bank vole invasion showed spatial sorting in behaviour, with voles being shyer at the invasion edge than at established ranges (Eccard et al. 2023, PRSLB). Voles were also more explorative at the invasion edge (Mazza & Eccard 2023 Curr Zool). Mice personality traits, however, did not differ among zones. We investigated behavioural differences between the two species, comparing 6 invasion and pre-invasion sites with camera traps (360 trap nights). Bank voles fed more efficiently than wood mice; wood mice did not prolong their activity pattern in response to the increased resource pressure through the bank voles. However, bank voles were not found displacing wood mice via aggression from good feeding sites. Our results indicate that wood mice have not evolved a flexible response to resource competition by bank voles, contributing to their massive decline in areas invaded by bank voles.

Personality variation is widespread in nature, yet its consequences for gene flow and evolution remain far less understood than the mechanisms that generate it. Personality influences how individuals use space, acquire resources, interact socially, and reproduce. Variation in personality is thus expected to lead to consistent individual differences in life history, as well as non-random patterns of habitat use, social encounters, and mate choice that may promote assortative mating. Despite frequent theoretical predictions, empirical evidence for these processes is scarce. We therefore experimentally tested whether behavioural and potentially associated phenological variation promote assortative mating and contribute to reproductive isolation.

In Dutch freshwater systems fragmented by anthropogenic barriers, formerly migratory three-spined sticklebacks (Gasterosteus aculeatus) have been forced into residency and diverged behaviourally and morphologically from their migratory ancestors within ~50 generations. As fishways now restore connectivity, it is critical to determine whether these populations are on a trajectory toward reproductive isolation and whether personality and breeding timing structure mating patterns during early secondary contact.

To test this, we released wild sticklebacks with known personalities (activity, aggressiveness) into replicate semi-natural mesocosms under three social treatments: residents only, migrants only, and mixed populations. Over three months, RFID tracking and clutch monitoring provided fine-scale data on breeding timing, and DNA-based parentage analyses identified mating pairs. This allowed us to quantify assortative mating by personality, timing and population as well as social effects on phenology. Our results provide new empirical insights into the role of personality in shaping reproductive isolation during early stages of population divergence.

Consistent individual differences in behaviour, known as personality, can influence a range of fitness outcomes, including survival, pairing success, and reproductive success. However, most personality studies to date have focused only on adult behaviour and so we know surprisingly little about the ontogeny of these behavioural differences. In this study, we systematically measured five major personality traits (boldness, exploration, activity, aggressiveness, and sociability) in 35 hand-raised greylag geese (Anser anser), using a combination of observational and experimental approaches. Behavioural measurements began when subjects were one week old and continued across their first two years of development, allowing us to assess the consistency of personality traits through to adulthood. We found that all five personality traits were significantly repeatable at the gosling stage (age 1–4 months), demonstrating that personality differences are present even very early in life. However, the consistency of these differences across ontogenetic stages differed among the five personality traits, which suggests that some behavioural axes are more sensitive than others to shifts in environmental or social context. Future work will investigate how early-life personality differences influence important social behaviours, including social network position and dominance, as well as fitness metrics such as survival and reproductive success.

Neophobia—the avoidance of novel stimuli—is an emotional response that shapes how animals interact with their environment. Although neophobia has been widely studied at the individual level, much less is known about how it manifests in social contexts, which may be critical in highly social species. We investigated neophobia in colonies of free-living jackdaws (Corvus monedula) breeding in artificial towers. During incubation, we introduced a novel object on the nest entrance ledge and quantified individual responses in relation to those of their partner and colony members. We measured latency to return, object interactions, and several reproductive parameters (clutch size, egg size, chick growth, fledging success). The experiment was repeated one week later. We found that jackdaws returned later during the first test than in the control, indicating neophobia, but showed habituation in the second test. Repeatability analyses showed that consistency in return latencies was low within nests (repeatability = 0.032, 95% CI: 0–0.134), but moderate within colonies (repeatability = 0.255, 95% CI: 0.04–0.47; p < 0.001), suggesting that colony-level factors influence neophobic behaviour. We hypothesize that breeding tower location drives colony differences through variation in environmental quality and nest competition.

A major goal of behavioural ecology is identifying sources of among-individual variation in behaviour. Theory suggests that life history traits and personality should be correlated at the individual level, but despite much attention, it has little support. A potentially crucial aspect influencing life history and personality associations that has been overlooked is sex. Males and females of many species differ in energy requirements, energy allocation, and behaviour, suggesting that sex may affect correlations between life history and personality differently; if so, not accounting for this possibility may obscure relationships.

We address this possibility by intensive longitudinal sampling of boldness and growth in 68 male and 92 female pillbugs (total N=160), using novel statistical methods to estimate sex-specific (co-)variances in a single parsimonious model. We found that males and females had similar mean boldness, similar among-individual variation in boldness and in growth rate, but females grew faster than males. We found that the correlation between boldness and growth was positive in males, but not significant in females. The sex differences in can potentially be explained by different selective pressures on reproductive fitness. Given the ubiquity of sex differences in life history, and sex-specific selection pressures on behaviour, this sex-specific approach to studying trait integration is likely to provide novel insights that to date may have gone unnoticed.

The study of female song is gaining momentum, after a decade of publications manifesting this gap in our knowledge. Nevertheless, quantitative descriptions of female song are still missing, even for well-studied model species. Here, we present a comprehensive view of female song in a colony breeding songbird, the spotless starling (Sturnus unicolor). Using passive acoustic monitoring near and inside the nestbox, together with PIT tag detection, we identified 51 individual females singing over a five-month period during the breeding season (2025). We found that female’s singing style was markedly different from the male’s. Furthermore, we found song motifs shared exclusively by females but not sung by any male, although many song elements are common in both sexes. Given that starlings are excellent vocal mimics, this finding is surprising and questions what neuro-ethological processes allow individuals to learn their song by mimicking virtually any sound, while preserving partially sex-separated repertoires. We also found that females sang near the nestbox for long periods similar to the broadcast song of males. This could serve as a nest defense or mate guarding strategy to prevent polygyny. Finally, we collected audio and video recordings of females singing in the nest during incubation, a rare behaviour that has been described only recently in two species. Our pilot playback study indicates incubation song might serve to reduce clutch sabotage, which is common in our population. Understanding how selection pressures shape song in each sex is a promising tool to unravel universal trends in the evolution of birdsong.

14 14. Animal personality

Babbling in humans, as well as other babbling species such as songbirds and bats, function as a way for infants to learn the adult language or tutor songs, respectively. In humans and pygmy marmosets (Cebuella pygmaea) however, babbling also seems to have the social function to elicit caregiver attention, a trait that may be essential in species with cooperative breeding where care is competed for between siblings. Common marmosets are cooperative breeders and are known to babble, yet they are already born with the full adult repertoire upon birth, prompting the question as to what they gain via babbling. Babbling function has been studied in captive pygmy marmosets but never in common marmosets, let alone in the wild. We recorded the context of all instances of babbling in 4 captive and 10 wild marmoset infants across ontogenetic time till they stopped babbling (between wk 0-37) through full day focals from April 2024-November 2025. All recordings were conducted in unrestrained settings within the family groups. By testing babbling across ontogeny, this enables us to pinpoint if the function of babbling changes with age and if it’s used instrumentally in diverse contexts. First results suggest there are contexts where babbling is more likely to occur than others and has the function to attract caregivers. This could imply that the social function may predate the learning function of babbling. Intriguingly, the results also show babbling occurs for longer than was previously described in the literature of 20wks and varies across individuals, which points to additional functions. If the analysis of the full data set confirms these patterns, our findings suggest babbling is not produced randomly but in specific contexts that facilitate infant survival.

African Penguins are colonial and highly vocal seabirds. Despite their rich vocal repertoire, detailed studies on the structure and function of particular vocalisations remain limited. In particular, the Mutual Display Song (MDS), which is produced jointly by both partners of a bonded pair, has received little attention in past research. While early descriptive studies recognised its connection to pair interactions and its socially contagious nature, its function has never been tested experimentally. We exposed pre-egg stage pairs at the nest to playback of stranger MDS, stranger Ecstatic Display Songs (EDS, uttered during the breeding season to attract mates and defend territory), and white noise, and monitored their behavioural responses. We hypothesised that exposure to stranger MDS would motivate couples to engage in pair-bonding behaviours. We found that penguins exposed to MDS playback all showed a strong trend towards exhibiting nest-related behaviours, courtship behaviour, and copulation, while such reactions were nearly absent in response to EDS and white noise treatments. Therefore, we showed that the playback of stranger MDS motivated pre-egg stage African Penguin couples to engage in pair bonding behaviours and copulation. This study reveals a potential synchronising function of the MDS for breeding behaviour in the African Penguin and opens up new possibilities for future conservation efforts, which might include MDS playback on a colony level to encourage nest building and copulation in this Critically Endangered species.

Amplitude is a key property of sound and a major factor in effective signal transmission. Animals relying on acoustic communication adjust amplitude to attract mates, maintain contact over distance, reduce eavesdropping, and compensate for high ambient noise. Despite its central role, amplitude remains one of the least studied aspects of animal signaling.

During early breeding seasons in 2024–2025, we recorded calibrated song amplitude in six common European passerines in north-eastern Poland. Using 3267 measurements from 20 individuals per species, we quantified song sound pressure levels (SPL) at 1 m and analyzed variation with song traits, social context, and environmental factors using Bayesian Generalized Linear Mixed Models.

SPL were 81 ± 2 dB(A) in Fringilla coelebs, 82 ± 3 dB(A) in Emberiza citrinella, 81 ± 2 dB(A) in Phylloscopus collybita, 82 ± 2 dB(A) in Phylloscopus trochilus, 81 ± 3 dB(A) in Curruca communis, and 88 ± 3 dB(A) in Acrocephalus arundinaceus. Models revealed that temperature, humidity, and time of day significantly influenced amplitude. Birds sang louder early in the day and under cooler, drier conditions. Among song traits, higher peak frequency was associated with greater amplitude, and song rate showed a weaker effect. Social context and ambient noise had negligible influence.

Our findings demonstrate that song amplitude is shaped by environmental and acoustic factors, highlighting its potential sensitivity to climate change and habitat alteration. Integrating amplitude into studies of avian communication is essential for understanding behavioral adaptation and predicting responses to shifting environments.

This research was funded by the National Science Center, Poland (2022/47/D/NZ8/00565). Conference participation was supported by the Polish Ministry of Science and Higher Education under the European Social Development Funds 2021–2027 program, project ‘Supporting students in improving their competences and skills’ (MNiSW/2025/DPI/6).

Acoustic communication is widespread across species, playing a crucial role in contexts like mate attraction, territory defence, predator avoidance, rival intimidation, individual recognition, and social interaction. In poikilotherm animals, such as amphibians, many vital functions, including sound production, are directly affected by the environmental temperature, which has been shown to strongly influence call performance and acoustic parameters in frogs. Calling is an energetically costly activity, driven by muscular contractions that are highly sensitive to temperature fluctuations. As temperature affects metabolic processes, it directly influences acoustic parameters such as call rate and call duration, which are tied to the efficiency of muscle function. Previous research showed that temperature can alter call rate, with frogs producing calls more rapidly at higher temperatures. Such adjustments are essential for maintaining effective communication, yet they may increase energetic demands and challenge the ability of individuals to transmit reliable signals under fluctuating environmental conditions. This study investigates how temperature influences the calling behaviour of the poison frog Allobates femoralis, a diurnal and terrestrial species inhabiting the rainforests of South America. Using continuous recordings of captive individuals exposed to both natural daily temperature cycles and experimentally controlled extreme temperatures, we quantify variation in calling activity and patterns of vocal behaviour. Preliminary results reveal strong temperature dependence, with activity drastically decreasing at lower temperatures and increasing under warmer conditions. This work provides insights into the thermal sensitivity of frog communication and offers a framework for understanding how changing environmental conditions may affect signal production, performance, and ultimately reproductive success in a warming world.

Understanding how closely related species coexist despite strong ecological similarity remains a central challenge in behavioural ecology. Using a multi-scale approach combining different sampling methods over 5 years, we investigated the mechanisms promoting the coexistence of 5 sympatric tit species in a managed mixed lowland forest in northern Italy across different phases of the circannual cycle. Across seasons, species consistently clustered into two habitat-based ecological groups: “broadleaf species” (blue tit, great tit, marsh tit) and “conifer species” (coal tit, crested tit). In winter, when species are non-territorial and forage in flocks, foraging microhabitat partitioning occurred within each group, with complementary exploitation of the tree canopy. Conversely, during breeding, all species foraged across the entire canopy, resulting in strong spatial overlap. Nevertheless, coexistence was maintained through interspecific spatial segregation of breeding territories. We then tested aggressivity responses of territorial males using playback experiments, assessing whether aggressive territorial behaviours occurred in response to heterospecific playback stimuli, and if responses were stronger towards species sharing the same habitat. “Broadleaf species” consistently showed higher aggression towards songs of species from the same habitat, whereas this pattern was absent in “conifer species”. We further tested whether interspecific territoriality was affected by nest-site (i.e. cavity) limitation by experimentally manipulating nest-box densities across different areas. In parallel, we assessed whether spatial overlap during breeding translates into trophic overlap by analysing nestling diet using DNA metabarcoding of faecal samples, suggesting dietary differentiation associated with the capture of different prey taxa. This study enhances our understanding of ecological and behavioural mechanisms driving coexistence among ecologically similar bird species.

The evolution of sensory systems is fundamentally governed by an organism’s life-history strategy. For phytophagous insects, oviposition is a high-stakes decision that directly links maternal fitness to offspring survival. While reliance on visual and chemical cues for host selection is well-documented, the role of plant-derived acoustic signals, indicative of physiological stress, remains largely unexplored. Here, we investigated how female Egyptian cotton leafworms (Spodoptera littoralis) utilize plant acoustics to evaluate host vitality. Using two-choice behavioral assays and high-resolution movement tracking, we show that S. littoralis females discriminate between drought-stressed and well-watered plants, guided by "acoustic eavesdropping" on stress-induced ultrasonic emissions. To assess whether drought stress is also encoded in olfactory cues, we recorded electroantennograms (EAGs) to whole-plant volatile blends in both sexes and quantified the hierarchy and separability of response profiles using machine-learning classifiers. Our data reveal pronounced sexual dimorphism in peripheral sensory tuning: female antennae exhibit superior temporal resolution, enabling finer discrimination of ecologically relevant signals. Notably, olfactory response patterns aligned more closely with plant physiological state than with taxonomic identity, suggesting an evolved function-based coding mechanism. This strategy may reduce cognitive load during rapid decision-making in complex environments. By integrating the acoustic detection of plant stress with temporally precise olfactory processing, S. littoralis optimizes maternal investment in unpredictable habitats. These findings highlight an underappreciated multimodal sensory pathway and provide new insights into the evolution of sensory integration in interkingdom interactions.

Animal life cycles are structured into seasons with major differences in behaviour. Yet much of our knowledge, and consequently the data that inform policy and predictive modelling, is drawn from studies conducted when animals breed. This seasonal research bias overlooks key seasonal and life stages in the ecology of animal populations, such as high over-winter mortality periods. Proposed hypotheses for this bias include increased methodological feasibility associated with studying breeding animals as well as a preference for asking breeding-related questions. We evaluate the structural and temporal characteristics of the animal ecology literature by reviewing >6,000 studies. Temporal trends in the seasonality of research effort shows only slight increases in non-breeding studies over the past decade, with the majority of data still being collected during the breeding period. Disentangling when data were collected from the research question focus reveals that the majority of studies address non-breeding questions (even if the data were collected during breeding), suggesting that feasibility is a key driver behind the disproportionate data collection during the breeding season. This hypothesis is supported by studies conducted during the breeding season being more likely to include experimental treatments and having larger sample sizes (more study individuals as well as more replications). Analysing the methods used in each study reveals that indirect approaches, notably biologging, are playing a key role in bridging the gap to non-breeding ecology. Thus, while the seasonal research bias is pervasive, it is primarily driven by the feasibility of collecting data when animals breed rather than questions focused on breeding per se. Achieving a more systemic understanding of animal behaviour and ecology will be achievable by investing in solutions that overcome limitations to data collection.

Female mimicry, when some males closely resemble female morphology to deceive and exploit the reproductive investment of dominant males, is common among nesting fishes. The disguise can be so convincing that even trained biologists struggle to tell them apart, complicating our ability to assess their true frequency and study their behavior. We tested whether artificial intelligence (AI) can determine sex in the corkwing wrasse (Symphodus melops) using 4,979 images from 1,666 wild-caught, individually tagged individuals of verified sex. The model substantially outperformed human experts in correctly distinguishing mimics from females (weighted F1 score: 95.4% versus 57.0%, mean of two experts). Furthermore, we find that sex-specific visual information is spatially distributed across the entire body, with particularly strong signals from the area just below the eye and around the urogenital papillae. Applying the trained model to new data from a population in a marine protected area showed a decline in female frequency relative to nesting males over a six-year period, while the proportion of mimics remained unchanged. This demonstrates the practical use of an objective and automated tool that can easily be adapted to other systems where photography and sexing are integrated into field sampling. The approach opens new opportunities for non-invasive studies of mimicry in the wild, for example by testing whether density dependence affects the fitness of different morphs, or by studying the effectiveness of the mimicry in situ as a function of individual traits and environmental conditions.

Individual identification (ID) is an essential part of the behavioral ecologist’s toolbox, but tagging can be costly and negatively affect the animals themselves. Visual ID provides a non-invasive alternative for species with individually unique markings yet quickly becomes impractical for humans in large populations. Recent advances in artificial intelligence (AI) have produced powerful models for automated individual re-identification (re-ID). However, because most animals’ morphology changes substantially over their lifetime, such models may struggle when observations are separated by long time spans. We explore this challenge and potential solutions through a case study of a fish with fingerprint-like facial patterns, Symphodus melops. We assembled an image dataset of 9861 wild-caught, PIT-tagged individuals spanning seven years. 1879 individuals were captured at least twice, enabling us to train and test metric-based deep learning models for closed-set re-ID. As expected, accuracy declined with increasing time between observations. To mitigate this, we constrained candidate matches using biologically realistic size-at-sampling estimates, spatial information, and sex.This allows unlikely matches to be identified and excluded, improving robustness over both short (<50 days; rank-5 accuracy > 0.95) and longer (>50 days; rank-5 accuracy > 0.70) time spans. We also developed AI-models for detection of key behaviors at nests in video data, which, when combined with re-ID, open new opportunities for studying individual variation in traits such as nest building, sneaking, courtship behavior, and mate choice. While our results demonstrate how integrating biological knowledge with AI can facilitate more ethical and scalable studies of animal behavior, further progress will require models that explicitly account for temporal changes in morphology. Achieving this will also depend on the availability of high-quality longitudinal datasets across species.

Complexity is a key feature of living organisms and therefore an essential component of biological research, including animal behaviour. But what role does complexity play in the formation and maintenance of animal mating systems? Animal mating systems describe the number of partners each sex mates with as well as the context in which mating occurs. Although they have been studied for centuries, their diversity across species and plasticity within species still remains a puzzle. We argue that adopting a complex systems perspective can improve our understanding of the conditions under which mating systems arise and how they are maintained in a population or species.

Here, we propose a framework that depicts mating systems as complex interactions of ecological, morphological and behavioural traits. Our approach uses methods from complex system science and network science to test whether mating systems can be identified from strongly associated traits across different species. To test our approach, we used spiders as a model taxon, since spiders show remarkable diversity in reproductive behaviours and strategies. We found consistent clusters of trait associations linked to specific mating rates per sex, patterns we describe as mating system syndromes. For example, we identified a syndrome with low male mating rates that included many behavioural traits known from monogynous species, such as sperm depletion and spontaneous male death. We therefore argue that mating system studies can benefit from a systems perspective, in which we can visualize mating systems as a network of traits that influence each other and give rise to a certain behaviour pattern. Considering complexity and potential trait interdependence, alongside environmental conditions, when studying mating systems opens a new way of analysing not only how mating systems arise but also their ability to change, even within species.

The intersection of animal ethics, welfare, and behavioural ecology requires robust ethical oversight to ensure responsible animal treatment. Animal sentience (capacity to feel both positive and negative emotions) is a core aspect of ethical research and essential for applying integrity oversight to behavioural ecology. This oversight is aimed at fostering public trust in science by promoting responsible and evidence-based research. The Animal Welfare (Sentience) Act 2022 (UK), is an example of how legal standards evolve, reflecting changing societal and ethical expectations regarding research. This act acknowledges vertebrates and certain invertebrates (e.g. decapod crustaceans) as deserving protection, highlighting the need for ethical considerations in research involving these animal taxa. Ethical oversight must not only address the welfare of animals but also the ethical duty of researchers to uphold high standards in study design, methods, and reporting. Current challenges in behavioural ecology research, which range from animal behaviour experiments to the use of invasive species management techniques, underscore the necessity of ethical scrutiny. The distinctions between routine veterinary practice versus clinical veterinary research, as well as wildlife management versus wildlife research, are useful examples that assist with guidance on ensuring ethical compliance. Researchers are encouraged to use established guidelines, such as the PREPARE checklist and ARRIVE guidelines, to enhance the ethical standards of their research. Ultimately, the ongoing dialogue surrounding animal ethics in research is crucial for maintaining high research standards and fostering public trust. Greater vigilance in reporting ethical and welfare problems is needed. Furthermore, requiring ethics declarations in conference submissions could promote greater accountability and integrity, ensuring that the welfare of animal subjects remains a priority for behavioural ecology research.

Adult sex ratio (ASR) is a fundamental parameter in population biology that varies widely both within and across species. Understanding the causes and implications of these variations is important for evaluating the significance of frequency-dependence in sexual selection, breeding systems and social behaviour, and also for managing wild and captive populations. However, estimating ASR is challenging due to spatial and temporal variations in male and female abundance, to sex-specific differences in detectability and to potential biases in sampling design. To address these challenges, we have compiled an extensive ASR dataset using published data from 2,056 wild populations representing 856 tetrapod species that included amphibians, reptiles, birds and mammals. Using phylogenetically controlled comparative analyses, we estimated the repeatability of ASR at both population and species levels and examined how estimation method, sample size, study duration and seasonality, and data quality influenced within- and between-species variation in ASR. We also tested temporal and spatial consistency in ASR estimates. By integrating data across a wide taxonomic range and diverse study designs, this approach allows us to evaluate the relative contributions of biological and methodological sources of variation in ASR. Our study offers guidance for data selection and study design for future research of adult sex ratio variation.

Anthropogenic stressors can strongly alter species interactions, reshaping trophic and non-trophic relationships and restructuring ecological networks. I will present how long-term exposure to artificial light at night (ALAN; 12 months in the wild), short-term exposure to elevated temperature (two weeks in aquaria), and prior experience with predators (wild-caught versus naïve fish) influence behavioural and physiological responses of coral reef fishes to conspecifics and predators. Experiments were conducted in a fully immersive, closed-loop virtual reality (VR) system designed for freely moving fish. The system integrates real-time 3D tracking, DeepLabCut-based posture detection, and viewpoint-updated rendering, enabling precise quantification of behaviour, gaze direction, and decision-making under highly realistic yet controlled conditions. A respirometry chamber was incorporated into the VR setup to measure metabolic responses to predation cues. This platform reveals clear, species-specific behavioural signatures, such as position, velocity, forward swimming, and including gaze–motion coordination not previously accessible in freely moving fish. We detect marked differences in conspecific attraction and predator avoidance among species, likely reflecting variation in social structure, mobility, and group size. Polynesian anemonefish exhibit a strong immobility response to virtual predators, accompanied by suppressed metabolic rate, but this response is weakened following long-term ALAN exposure, potentially explaining reduced survival observed in the wild. Elevated temperature also modifies antipredator behaviour, with effects correlated to metabolic performance across species. This VR framework provides a powerful and flexible tool to investigate how anthropogenic stressors shape perception, decision-making, and species interactions in aquatic animals.

Cooperative breeding is a key steppingstone from solitary to social and eusocial systems, yet its early evolution remain poorly understood. The Asian burying beetle, Nicrophorus nepalensis, offers a powerful model to address this gap. This subsocial species exhibits complex biparental care, including intensive pre-hatching investment through carcass preparation and burial, which serves as a food source for larvae. Around this parental system, cooperative interactions among non-breeding individuals have evolved.

Using two populations, we show that interspecific competition with blowflies induces population- and sex-specific cooperative strategies. In the high-elevation, year-round breeding Hehuan population, cooperation emerges primarily among females, whereas in the low-elevation, seasonally breeding Yang-Ming population, males drive the cooperative response. This represents a rare form of sex-role reversal: dominant females remain the primary carers, but the identity of subordinate helpers shifts between populations.

Hybridisation experiments support a genetic basis for these differences. F1 hybrids display cooperation in both sexes and intermediate parental care, consistent with a 13 Mb chromosomal inversion present in Yang-Ming (+/+) but absent in Hehuan (–/–). The combined phenotype of hybrids (+/–) implicates this region in cooperative behaviour.

Sex-specific cooperation is associated with divergent social and reproductive outcomes. Female cooperation reduces female aggression, whereas male cooperation does not. Sex ratios, timing and efficiency of pre-hatching care, and reproductive success differ depending on which sex cooperates. Notably, larval mass remains stable under blowfly competition only when both sexes cooperate.

Together, we show that cooperative breeding in N. nepalensis is shaped by both plastic and evolutionary processes, highlighting how sex-specific cooperation and local adaptation drive diversification in early social systems.

The evolution of biparental cooperation across diverse animal taxa remains a longstanding puzzle in evolutionary biology. Although both parents share a common fitness interest through their offspring, each incurs the direct costs of care individually, creating a well-defined cooperative dilemma. Many theoretical studies have proposed that biparental cooperation can be stabilised when males and females specialise in different care duties or negotiate to coordinate their investment. Empirical evidence, however, offers mixed support for these predictions, suggesting that parental cooperation does not follow a single universal rule. Using comparative data on birds, where biparental care is most prevalent, I reveal striking diversity in how parents cooperate. In some species, parents divide tasks clearly, with each performing distinct activities; in others, parents cooperate continuously throughout the breeding cycle; and in still others, parents specialise in different tasks early on and later coordinate joint feeding of the young. In my talk, I will show how these cooperative strategies are distributed across bird species, identify which strategies are evolutionarily stable and resist transitions to alternative care patterns (e.g., female-only care), and explore the ecological and evolutionary conditions that favour a particular form of parental cooperation.

To parents, the value of the brood typically increases with offspring number because more offspring may reach independence and reproduce. Therefore, parents should invest more in larger broods; accordingly, for example, in passerine birds, parental provisioning during nestling growth should be greater for larger broods. Southern House Wrens (Troglodytes musculus bonariae) are year-round residents, socially monogamous, and small hosts of the obligate brood parasitic Shiny Cowbird (Molothrus bonariensis). During 2023-2024 in Buenos Aires, Argentina, we studied parental provisioning and nestling growth in 55 experimental broods differing in nestling composition, containing four wrens, seven wrens, or four wrens plus a cowbird. At each brood, we quantified adult provisioning behavior at 4- and 8 days posthatch using video cameras. Estimated body mass of fledglings from four-wren broods was higher than for seven-wren broods, while it did not differ from parasitized broods. In turn, maximum relative growth rate did not differ with brood composition. Parent wrens appear to compensate provision rates in large and parasitized broods by delivering more food than at small broods: at 8 days of age, the total provisioning rate of parasitized broods was twice that of four-wren broods, and the provisioning rate of the cowbird nestling was similar to that of the four wren nestlings in the brood. Remarkably, provisioning rate per wren nestling did not differ with brood composition either at 4- or 8 days. Our results are in line with parental investment and brood value predictions as wren parents increase feeding effort with brood size and chick need, but they also do not appear to discriminate against the parasitic nestling.

Parental care is widespread across taxa and often requires significant energetic investment. Because all individuals have a limited energy budget, these energetic demands necessitate life-history trade-offs in care-giving parents. Although life-history trade-offs associated with parental care have been well studied, less attention has been devoted to whether and how adaptive divergence, particularly diet specialization, shapes life-history strategies in care-giving species. Previous work shows that diet can influence life-history strategies at both developmental and evolutionary timescales; however, we know little about how the evolution of diet specialization may drive variation in parental care or the life-history trade-offs associated with it. Here, we use Alaskan populations of diet-specialized threespine stickleback (Gasterosteus aculeatus) ecotypes to ask: 1) does diet specialization drive variation in care behaviors, and 2) does diet specialization affect life-history trade-offs associated with care. Our results will identify potential ecological variables shaping the evolution of parental care with implications for care-mediated effects on offspring development.

Allomaternal care, where non-maternal caregivers assist with infant care, is predicted to provide benefits to the care receivers and to incur immediate costs to the care providers. Yet, few studies have investigated the physiological consequences of allomaternal care, typically focusing either on caregivers or care receivers, but never adopting a holistic approach that considers all actors simultaneously. Here, we study the physiological correlates of allomaternal care in a semi-captive Asian elephant population from Myanmar. We use behavioural data on allomaternal care from 52 mothers, 59 calves and 44 allomothers, coupled with faecal glucocorticoid metabolite (FGMs) and body condition (BC) measurements, to test (i) whether the presence of an allomother, her reproductive experience, and allonursing impact mother’s and calf’s FGM concentrations and BC, and (ii) whether allomaternal care impacts the same outcomes in allomothers. Mothers had lower FGM concentrations when receiving help from a nulliparous allomother, whereas calves had lower FGM concentrations when receiving care from allomothers with no dependent calves, regardless of their parity. Calves had higher FGM concentrations when their mother was allomothering another calf. Allonursing did not impact FGM concentrations, but tended to improve maternal body condition. Providing allomaternal care was associated with lower FGM concentrations in nulliparous and parous females with no dependent calves. Our findings show that allomothers’ traits mediate the physiological consequences of allomaternal care, and reveals divergent “optimal” allomothers for mothers and infants. Our study further suggests that allomaternal care is low cost in our population, and could be used as part of reciprocal exchanges between females.

Background.

Diet may be the main driver of the extensive paternal care and reduced maternal care seen in the bat-eared fox (Otocyon megalotis), a termite-specialist that only rarely consumes vertebrates. Lactating, physiologically challenged females tend to invest more heavily in foraging, while males spend more time with the pups. However, we know little about changes in foraging behavior and stress in bat-eared fox parents.

Methods.

Using focal observations of habituated individuals, we studied foraging behavior in 20 wild bat-eared foxes for two years, describing how foraging behavior and fecal glucocorticoid metabolite (fGCM) levels varied with austral season and parental status.

Results.

We found that small item consumption and overall daily foraging rates were lowest for all foxes in winter. Male foxes, specifically, increased foraging rates in spring, while all foxes ate more large items in summer. Some parents exhibited innovative foraging behaviors during the period of pup dependence, including surplus killing of vertebrate prey. Mean fGCM levels in the population (0.41 µg g-1 organic content) were not affected by sex or austral season but did change with seasonal activities: parents had significantly lower fGCM levels in the breeding season.

Conclusions.

Our findings suggest that behavioral adaptations, including foraging adaptations, are sufficient for bat-eared foxes to meet the physiological challenges of parenting. Parents may indeed experience reduced stress due to successful pairing and within-family socialization during the breeding season. This is the first study to start unravelling the intricate relationship between foraging, reproduction, and stress-related hormone levels in the bat-eared fox.

Parental care has been found to promote greater standing genetic variation and to buffer against mutation load, but the importance of these processes remains unclear in wild populations. We tested whether inbreeding depression and parental care varied among six different neighboring woodland populations of Nicrophorus vespilloides. If local variation in care causes mutation load to increase, we would expect populations with a greater inbreeding depression to display longer durations of parental care. Burying beetles (N. vespilloides) provide elaborate biparental care for their larvae, which involves converting small vertebrate carrion into an edible nest, defending the nest, and provisioning larvae. N. vespilloides larvae are facultatively dependent on post-hatching care and experience natural variation in the duration of post-hatching care. Our previous work found that wild populations do indeed vary in their inbreeding depression. To test whether they also vary in duration of care, we bred pairs from each population in a box with two chambers separated by a one-way exit valve, which allowed beetles to end their supply of care at a time of their choosing. Boxes were checked every four hours during the breeding period, and beetles found in the exit chamber were removed. Preliminary results suggest that most populations do not differ in duration of care, except for females from one population, which provided less care. There does not appear to be a relationship between duration of care and inbreeding depression among these populations of N. vespilloides. Further work on the demography of these populations and more fine-scale measurements of care behaviour will help us better understand the relationship between parental care and mutation load in this species.

Encoding individual characteristics in long-distance animal signals is widespread. This broadcast can be particularly refined in species that produce songs composed of motifs, phrases, and acoustic units that differ in duration and spectral properties. Among non-human primates, some species likewise produce songs as extended sequences of units organised into phrases, often marked by pronounced frequency variation. The indri (Indri indri), an iconic lemur of Madagascar’s eastern rainforests, produces near-daily choral songs. Spatially segregated family groups that actively defend territories by chorusing alternate phrases built from units with distinct frequency characteristics. To test whether individuals of both sexes exhibit idiosyncratic song and unit features, we conducted a multi-level analysis of phrase–unit combinations and of unit duration and frequency structure. Phrase–unit combinations differed consistently between the sexes, with females showing greater variability within and among individuals. At the unit level, inter-individual variability was striking, as supported by a dataset comprising more than 84,900 units. Focusing on the most distinctive units per individual and classifying them with a random forest, all individuals were identified above chance, and 44 out of 79 indris exceeded chance by more than 25%. These findings indicate that individually distinctive traits are encoded in both the combinatorial organisation and the temporal–spectral features of indri song units, providing a potential basis for individual recognition in a territorial species where direct encounters are rare and acoustic cues may support dispersal and pair formation.

Formants are resonance frequencies shaped by the upper vocal tract. Across vertebrates, they encode key information in acoustic communication. Humans exert fine-grained control of formant modulation; little is known about such control in other species. Here, we test whether and how a harbor seal (Phoca vitulina) male can learn to shape formants. We trained one individual to modify a baseline vocalization via upper vocal tract movements – the opening and closing of the mouth – resulting in a conditioned vocalization. The seal also had to maintain the baseline vocalization throughout the experiment. Over 150 days, we audio- and video-recorded 455 baseline and 640 conditioned vocalizations. We extracted the first three formants (F1, F2, F3) and quantified their within-vocalization modulation via complementary measures. Through deep learning, we video-tracked crucial facial and spatial reference points, allowing us to quantify mouth opening and to map it to formant dynamics. First, formant contours revealed that F1 and F3 were similar at the start but diverged over the experiment. Second, F1 contours’ coefficients of variation were higher in the conditioned vocalizations at the end of the experiment. Third, F1 and F3 modulation depth, measuring frequency variation between adjacent time points, was higher in conditioned vocalizations. Fourth, formants’ spectral entropy decreased only in conditioned vocalizations, indicating a more predictable energy distribution throughout the experiment. Fifth, machine learning techniques confirmed that baseline and conditioned vocalizations differed in their modulation parameters at the end of the experiment. Sixth, mouth opening increased F1 and F3, but did not affect F2. Our findings show that (1) an adult harbor seal can be trained to open and close its mouth while phonating; (2) the conditioned vocal output contains more modulated formants than the baseline vocalization; (3) formant dynamics map to mouth opening and closing.

Sleep is essential for many animal behaviours such as learning, memory retention, and communication. However, birds living among humans are constantly faced with sleep disturbances such as urban light, noise, and traffic. Studies have shown that a lack of sleep can decrease the song performance of adult birds. Juvenile songbirds rely on learning and memory to produce high-quality songs as adults. Yet, no study to date has tested whether sleep disturbances in juveniles affect song learning and crystallisation. Our study used a model bird species, the zebra finch (Taeniopygia guttata), to investigate whether experiencing chronic sleep disturbances during the critical song learning window affects how birds learn their songs. We experimentally disturbed 14 male zebra finch chicks for up to 20% of every night during the sensory and sensory motor phases (ages 35 to 75) and compared them to 16 undisturbed birds. Both control and experimental birds received an unrelated tutor playback until song crystallisation (Day 100). We recorded individuals’ vocalisations during their sensory motor phase until song crystallisation. We then compared song characteristics such as peak frequency, average entropy and song similarity to the tutor song during the song learning period and post-song crystallisation. Preliminary results suggest clear differences in the songs of experimental and control males, suggesting that sleep disturbances during the juvenile period can alter adult song. These results inform how songbird species may be affected when sleeping under chronic disturbances, such as those experienced by urban birds.

In highly territorial species with acoustic communication, it is crucial for individuals to accurately assess the distance to other signalling territory holders and potential intruders – an ability termed “acoustic ranging”. Animals use this mechanism to maintain individual spacing which helps avoiding costly physical conflicts between neighbours. Likewise, accurate ranging can mediate engagement of intruders, when tolerance thresholds are passed.

While signal amplitude can provide a first orientation of source distance, it is not a reliable cue as animals can modify their calling or might call directional, or the signal path could be blocked by obstacles, or signals be modified through resonance, refraction or interference. Two distance dependent characteristics of sound transmission have shown to be rather robust against these influences: the signal-to-reverb-ratio, which incorporates amplitude- and runtime differences between the direct sound and reverberations from the environment, and distance-dependent frequency attenuation, which reflects the spectral-filtering function of a particular acoustic habitat over distance.

In the poison frog Allobates femoralis, a pan-Amazonian species, characterised by strong territoriality and prominent acoustic communication, we previously showed that males show decreasing responses to conspecific signals coming from increasing distance. Their response was independent of signal amplitude and changes in the signal-to-noise ratio. To further elucidate the cues used in acoustic ranging, we now used artificially reverberated signals and signals with artificial spectral filtering to simulate calling intruders at varying distances. Here we present first results on the differential response of the frogs to these distance cues, which provides deeper insight into the mechanisms of how animals perceive and evaluate acoustic distance.

Spontaneous entrainment to rhythm, or keeping the beat, is the core of human musicality, and as such may have adaptive significance. Entrainment is also known from group behaviours of some invertebrates and amphibians, but it is controversial whether the benefits of synchrony achieved extend beyond the individual level. Additionally, no convincing evidence has been provided for the use of entrainment in group signalling in other higher vertebrates, in which coordination typically results from training and relies on local call-and-response mechanisms. Here, we investigated the structure, mechanism, and function of duets in the little crake (Zapornia parva), a non-passerine bird species in which mated males and females produce extremely fast alternating trills, with 23-ms pulses repeated at approximately 30 Hz. Analysis of natural trills revealed their high isochrony and perfect alternation in duets. When we played solo trills to unpaired birds, they spontaneously joined them to form duets despite no prior training. Moreover, birds matched their isochronous trills to the playback even when the playback tempo was altered (10% faster or slower), when a single random note was omitted, and when every third note was removed to create a novel rhythm. In contrast, they failed to join non-isochronous solos with randomised inter-note intervals, strongly suggesting that entrainment of intrinsic rhythms—rather than note-by-note coordination—underlies duet formation in little crakes. Finally, when we played regularly alternating and irregular duets to territorial mated pairs in the playback experiment, the former elicited stronger reactions. This demonstrates the importance of alternation achieved through entrainment in territorial interactions. Overall, our results show that mated little crakes not only synchronise their extremely fast trills via entrainment, but that this cooperative behaviour is adaptive.

Animal culture is increasingly recognized as a component for conservation due to its role in population resilience and adaptability. In passerines, vocal culture facilitates information flow and reproduction. Globally, habitat fragmentation affects bird populations, yet its cultural impacts remain underexplored. Fragmentation can drive cultural drift, reduce song diversity, and alter transmission pathways. Our study examines how fragmentation shapes movement and vocal culture of the Korimako (Anthornis melanura) in Tawharanui Regional Park, a predator-controlled sanctuary with a mosaic of forest patches ideal for studying small-scale fragmentation effects. We: (1) track movements of banded individuals within and between patches; (2) record male and female songs to assess spatial variation; (3) measure morphological traits to detect habitat-linked clustering; and (4) conduct a cultural transmission experiment to test the uptake of a new song variant. Preliminary results suggest both sexes move between patches, especially in autumn, with higher dispersal probability in females. Most individuals show high site fidelity year-round. Distinct male and female song variants occur in marginal habitats with high edge proportion. Morphological clustering indicates heavier birds with shorter wings and tails remain in central habitats with abundant resources, while slimmer, longer-winged individuals dominate isolated patches, suggesting adaptation to commuting. By integrating movement, morphology, and song, we aim to map cultural diffusion across fragmented landscapes and uncover links between vocal culture, dispersal, and adaptation.

Stereotyped whistles fulfilling the SIGnature-IDentification (SIGID) criteria have been proposed to function as individual signature whistles in several delphinids other than the bottlenose dolphin. However, their evolutionary distribution across species remains poorly understood. We investigated the occurrence of these signals in four oceanic delphinids (Stenella attenuata, Stenella longirostris, Peponocephala electra, and Grampus griseus) living in sympatry in the Shisiwani National Park (Anjouan, Comoros Archipelago). Acoustic recordings were collected during dolphin encounters across three field seasons (May–September 2023, 2024, and 2025) using an HTI-96-MIN hydrophone towed from a local fishing boat at −5 m depth and digitized with a ZOOM H5 recorder. We visually inspected spectrograms and extracted whistle contours to detect whistle sequences matching the SIGID criteria. We then examined and quantified their occurrence within species’ repertoires and characterised their acoustic structure. We found that signature-like whistles occurred in all species, but the frequency of use and acoustic features differed markedly. Congeneric Stenella sp. showed closer acoustic similarity, while P. electra, and G. griseus occupied more distinct regions of the whistle space, consistent with phylogenetic expectations. All together, these results support the view that signature whistles, first described in bottlenose dolphins, may represent a widespread adaptation among delphinids, allowing individual recognition and social cohesion in fission–fusion societies where groups frequently split and reunite. From a practical standpoint, we also suggest that signature whistles may function as natural acoustic “marks” within capture–recapture frameworks, enabling the tracking of individuals and the estimation of population trends in these threatened dolphin species.

Vocal production learning is known to occur in several non-human taxa, including cetaceans, bats, elephants, and certain birds such as parrots, hummingbirds, and songbirds. Among birds, songbirds such as zebra finches are often studied as closed-ended learners, acquiring their vocal repertoire only during an early sensitive period, whereas open-ended learners like parrots can acquire new vocalizations throughout life. However, few relatively little attention was paid to learning process of open-ended learners at different developmental stages. Whether open-ended learners such as budgerigars (Melopsittacus undulatus) maintain high-level vocal learning ability into adulthood remains underexplored. Here, we investigated age-related differences in vocal learning capacity in budgerigars by comparing their ability to learn human speech sounds at different ages. We found that adult budgerigars retained the capacity to learn human vocalizations, providing clear evidence for vocal learning in adulthood. However, compared with juveniles, adults showed a lower probability of successful learning, slower learning rates within the same training period, and reduced overall imitation accuracy. Interestingly, adults exhibited significantly higher sequential similarity in vocal output than juveniles. Our findings demonstrate that parrots can acquire new vocalizations across species during adulthood and reveal age-related differences in vocal learning ability. These results provide experimental evidence for understanding open-ended vocal learning and its changes across the lifespan, and offer insights for comparative studies of human speech learning and evolution.

Vocal mimicry occurs in nearly 20% of songbird species, yet the constraints on accuracy and its consequences for function remain poorly understood. Body size is known to affect vocal performance in birds, but there appears to be no study of how body size affects mimetic accuracy and subsequent function. We examined how body size disparities between brown thornbills (Acanthiza pusilla) and the model species they mimic affect the accuracy and function of mimicry. Brown thornbills are tiny (7g) songbirds that mimic the alarm calls of multiple sympatric species to deceive nest predators like the pied currawong (Strepera graculina). We found that accuracy was variable among thornbill mimetic calls, and that mimicry of larger model species was less accurate than mimicry of smaller species, especially of lower-frequency call components. Furthermore, female thornbills, that are 13% lighter than males, appeared to be less accurate than males. To test the consequences of mimetic accuracy, we carried out a playback experiment on pied currawongs, exposing them to alarm call mimicry of variable accuracy. Preliminary analysis suggests that currawongs may respond more strongly to more accurate mimicry. Detailed analyses of the types of responses, intensity of vigilance and response latency are in progress. By examining how body size affects mimetic accuracy and the subsequent response of receivers, this study promises to advance our understanding of the constraints on vocal mimicry and how they affect mimetic function.

In group-living animals, individuals can often benefit from directing vocalizations to specific individuals. In common vampire bats (Desmodus rotundus), females form cooperative relationships with certain group members. In the complete darkness of their roosts, they recognize and find these same-sex social partners using individually variable contact calls. Recent work shows that cooperative food sharing rates predict both contact call similarity and calling rate. But how can a calling bat “address” a specific recipient in a dark, crowded, and noisy environment? Studies of dolphins and parrots suggest that callers can increase the likelihood of vocal recognition and response by producing a call that resembles the intended receiver’s most recent calls.

To test this vocal matching hypothesis, we repeatedly recorded vocal interactions within isolated pairs of eight common vampire bats from the same colony (28 pairs, three recording sessions per pair, 3686 calls). About 10% of calls received responses within 5 s of the focal call. To determine if call responses were predicted by vocal matching, we first quantified pairwise call similarity using dynamic time warping. We then fit a logistic multi-membership model to determine if the probability of a response was greater when a bat’s calls were more similar to the partner’s previous five calls.

We found that receivers were more likely to respond to calls that were more similar to their own recent calls. Specifically, response-eliciting calls were ~20% lower in acoustic distance than non-response calls on average. These results support the vocal matching hypothesis that vampire bats use rapid vocal convergence to address specific social partners. Vampire bats might use this ability to coordinate behaviors such as social foraging and cooperative food sharing after unsuccessful foraging.

Animals often eavesdrop on signals intended for others to gather information about their environment. While adult animals have been shown to learn to recognize unfamiliar heterospecific alarm calls through both social and asocial learning, it remains unclear whether and how young animals learn to recognize unfamiliar alarm calls. We show experimentally that nestling Daurian redstarts Phoenicurus auroreus can socially learn to recognize unfamiliar heterospecific alarm signals by associating them with conspecific alarm calls. We trained nestlings by presenting two unfamiliar sounds, one together with conspecific alarm calls (training) and one without (control). Before training, nestlings showed similarly little response to both novel sounds. After training, however, nestlings showed clear anti-predator responses to the training sound, but not to the control sound. These results show that nestling birds can socially learn to associate novel sounds with known alarm calls, even without visual confirmation of danger.

Wild species in temperate regions face increasing pressure as climate change rapidly reshapes their environments, often driving shifts in the timing of key annual events (phenology). While phenological responses are well documented in birds, far less is known for mammals, particularly marine mammals.

In this study, we analyzed climate-driven changes in birth timing for two top marine predators of the St. Lawrence River in the Northwest Atlantic: grey seal (Halichoerus grypus) and harbour seal (Phoca vitulina), over the past two decades (1998-2025). Despite being sympatric, these species give birth months apart (early winter for grey seal vs. late spring for harbour seal), providing a natural contrast to compare phenological responses.

We rely on transitions between neonatal developmental stages (neonatal moult in grey seal and umbilical cord degeneration in harbour seal) to model each species’ birth distribution using a Bayesian framework incorporating long-term trends and environmental drivers. Sea ice cover duration was included as a proxy for winter severity and its effects on maternal foraging and habitat availability, potentially influencing birth phenology.

Both species show advanced birth phenology, but at different paces. Grey seal shows a marked shift, with a median birth date ~16 days earlier than in 2004 (99% probability), whereas harbour seal exhibits a more modest ~3-day advancement since 1998 (89% probability). Shorter ice cover duration is associated with earlier median birth dates similarly in both species, with an advancement of ~1 day per 10 days of reduction in sea ice cover.

These findings suggest that both species are adjusting their birth phenology in response to climate change, with shorter ice periods also associated with earlier births. Comparing pinnipeds with asynchronous reproductive cycles improves our understanding of phenological responses and the potential environmental cues and mechanisms driving them across species.

Artificial light at night (ALAN) is a pervasive urban driver that can reshape coastal communities, yet its links to genetic structure and behavior remain unclear. Here, we examined two closely related isopods, <i>Ligia laticarpa</i> and <i>L. furcata</i>, across Tokyo Bay along a gradient from brightly lit inner-bay shorelines to darker, vegetated outer-bay coasts. Genomic and mitochondrial evidence consistently identified clear genetic segregation between outer- and inner-bay populations corresponding to the two species, with <i>L. laticarpa</i> predominating at inner-bay and <i>L. furcata</i> at outer-bay sites. While individual genetic profiles showed little indication of recent hybridization, population signals in several inner-bay sites pointed to historical inputs or local co-occurrence of distinct lineages, possibly mediated by ships. Bayesian modeling of 28 years of environmental data identified nighttime light intensity, salinity, and vegetation cover as major predictors of species occurrence, highlighting ALAN as a key environmental axis distinguishing their habitats. In laboratory assays, chronic ALAN exposure reduced growth and activity in <i>L. furcata</i> but had limited effects on <i>L. laticarpa</i>. These findings suggest that artificial lighting and maritime activity jointly shape patterns of genetic connectivity, habitat segregation, and physiological plasticity between closely related coastal species, providing insights into how anthropogenic disturbances influence ecological divergence.

Climate change is increasing the variability of weather conditions experienced by migratory species during migration and wintering. Furthermore, environmental conditions at wintering sites are often poor predictors of conditions at breeding sites. This potential mismatch makes it difficult for individuals to synchronize their activities with local resource abundance, potentially leading to carry-over effects, in which past conditions influence later performances. Our project assesses the effects of environmental conditions at wintering, stopover and local breeding sites on individuals’ performance (body mass and reproductive success) in female Tree swallows (Tachycineta bicolor), an insectivorous migratory passerine bird. To achieve this, we integrated data collected from citizen science (GBIF), meteorological databases, and a long-term study on marked individuals in southern Québec (2004–2025). Our preliminary results revealed that spring conditions at the local breeding site affected female body mass, while those experienced during wintering and migration had no detectable effect. In particular, female body mass decreased with increasing average precipitation (–0.40 g/mm) and with higher minimum temperatures (–0.14 g/°C) between arrival and incubation at the local breeding site. Our results suggest limited carry-over effects related to conditions during migration and wintering but highlights the major role of local spring conditions on birds’ physical condition, which can directly influence their reproductive success.

Truly dark skies are rare in many parts of the world due to the widespread effects of Artificial Light At Night (ALAN). Impacts on nocturnal and crepuscular species vary according to their level of tolerance to such disturbance. Whilst light-avoidance behaviour during commuting and foraging in light-averse species such as the lesser horseshoe bat Rhinolophus hipposideros is well documented, and delayed emergence has been linked with higher levels of light pollution, little is known about the effects of light pollution on bat behaviour at the roost. If emergence is delayed by brighter skies, what are the knock-on effects on preceding activity levels?

We installed cameras in ten lesser horseshoe bat maternity roosts across North Wales, UK, between April and September 2025 to quantify in-roost activity levels and emergence timing. These roosts varied in their proximity to sources of ALAN and in other measures of anthropogenic disturbance, such as distance to major roads. We quantified sky brightness continuously using a data-logging sky quality meter at emergence points, finding evidence of light pollution at all roosts. After controlling for weather, sunset timing and moon phase, we found that emergence was delayed at roosts experiencing higher levels of light pollution. This delay was associated with changes in activity levels and light sampling behaviour inside the roost.

Delayed emergence means less time available for foraging and increased in-roost activity wastes valuable energy reserves, particularly important during the breeding season and in advance of going into torpor. We therefore conclude that ambient light pollution can have subtle effects on in-roost behaviour in this species that are predicted to have negative consequences for fitness. This study contributes to the growing evidence base that minimising light pollution plays an important role in mitigating against anthropogenic disturbance to light-sensitive bat species such as the lesser horseshoe bat.

Heatwaves are extreme climatic events driven by climate change that strongly affect animal survival and reproduction and their impact might also extend beyond direct exposure. The potential for heatwave-mediated parental effects has been rarely investigated and especially during pregnancy, a costly phase for viviparous animals due to high metabolic demand that increases with time across the gestation. Here, female guppies (Poecilia reticulata), a small viviparous tropical fish, were exposed to a 5-days simulated heatwave during either early or late pregnancy. We quantified the effects of maternal heat exposure on female condition and fertility and on various offspring traits. Our results reveal effects on both fertility and maternal effects. On female fertility, there were size-dependent effects, with larger females exposed to high temperature during late pregnancy more likely to produce larger broods but with greater within-brood mortality than smaller females. These females showed reduced body condition, reflected by slower critical swimming speed. Maternal heat stress during late, but not early, pregnancy led to changes in offspring behaviour and sexually-selected traits. Offspring of late-pregnancy exposed mother exhibited increased explorative behaviour and higher swimming velocity in an open field test. These differences were independent of offspring’s condition, as body size and critical swimming speed did not differ across maternal treatments. Interestingly, adult male offspring (F1) from late-pregnancy exposed females displayed larger orange coloration. Overall, our results show that heatwaves during late stages of gestation can alter females’ fecundity and induce maternal effects shaping offspring behavioural and sexually-selected traits development. Changes in offspring exploration and sexual ornaments may influence dispersal and mating success, highlighting the complex and broad ecological and evolutionary implications that heatwaves may have.

Behavioural adjustments are among the fastest responses to human-induced rapid environmental changes. Animal personality and behavioural syndromes (i.e. correlations between behaviours) can constrain or facilitate adjustment to anthropogenic stressors and rapidly changing environments. Therefore, it is crucial to understand under which conditions among-individual differences in behaviour are consistent and correlated across behaviours. In this study, we examined how behavioural correlations shift under thermal stress and evaluated experimentally how boldness and activity respond to the combined influences of climate change and urbanisation. We collected 225 synanthropic arthropods, rough woodlice (Porcellio scaber), along a gradient of urbanisation in Münster, Germany. We repeatedly phenotyped behaviour related to boldness and activity over short (10 days) and longer (37 days) time periods, and exposed individuals to a 6-day experimental heatwave at 28 °C (N control = 112; N heatwave = 113). Our results revealed that (i) woodlice personality did not vary along the rural-urban gradient, and that (ii) a boldness-activity correlation emerged when individuals were kept for longer periods or were exposed to elevated temperatures. This suggests that behavioural syndromes arise under certain constraints or trade-offs. Moreover, (iii) individuals exposed to elevated temperatures exhibited decreased boldness, and (iv) this heatwave response was independent of the degree of urbanisation. These results suggest that ground-dwelling arthropods may be less sensitive to larger-scale environmental changes (i.e. urbanisation), but exhibit plastic behavioural responses to changes in ambient temperature. The stability of microhabitat conditions may therefore be a key factor in determining how arthropods cope with human-induced rapid environmental change.

Road traffic noise is increasingly recognised as a key driver of human–wildlife conflict, yet its direct effects on wildlife are difficult to disentangle from co-occurring disturbances such as pollution and habitat fragmentation. To isolate the role of noise, we conducted a BACI (Before–After–Control–Impact) experiment in summer 2024 in the mountains of northern Greece, using a phantom road equipped with camera traps and Audiomoths to expose free-ranging mammals to controlled playback of conventional and electric vehicle (EV) traffic noise. Mammal detections declined during noise exposure, indicating that traffic noise alone is sufficient to elicit behavioural responses consistent with disturbance. For most species, responses were similar under conventional and EV noise, suggesting limited sensitivity to differences in vehicle type. Only brown bears showed evidence of noise-type sensitivity, with fewer detections during conventional traffic playback compared to EV noise. Together, these patterns suggest that although EVs reduce noise emissions at low speeds, their behavioural effects on most free-ranging mammals remain comparable to those of conventional vehicles. Ongoing analyses are further exploring how traffic noise influences spatial use and movement patterns across species within the landscape.

In the lab, diet has been found to greatly influence cognition through different pathways, particularly during development. Specifically, high-fat high-sugar (HFHS) diets reduce learning and memory. Yet, very little is known on the effect of diet outside of the very controlled lab environment, and outside of key lab taxa such as rodents. In urban environments, species such as pigeons are often exposed to HFHS diets. In this study, we provided a HFHS diet and a control diet for 4 weeks to two groups of young racing pigeons, after which they all received the control diet (n=96). When individuals were trained to return to their home loft, unlike what we predicted, individuals on the HFHS diet were (1) faster at finding the home loft, (2) faster at learning, (3) explored less and as a flock were (4) less cohesive and coordinated than individuals in the control group. We also found effects of diet on the gut-microbiota. The gut-microbiota, through the gut-brain axis, can influences how individuals make decisions. Diet induced gut-microbiota diversity changes could explain behavioural differences in both social and individual navigation, by affecting what sensory information they obtain and how they process it.

Cognition underpins how animals perceive, navigate, and respond to their environment, yet these fundamental processes are increasingly threatened by environmental pollutants. Neuroactive pharmaceuticals are now routinely detected in aquatic ecosystems, raising concern about their potential to disrupt key cognitive functions in wildlife. Here, we tested whether exposure to the antidepressant amitriptyline, a widespread pharmaceutical pollutant, impairs spatial learning in wild-caught guppies (Poecilia reticulata). Using a repeated-trial maze assay, we quantified learning performance across 12 trials following an 11-d exposure to either a freshwater control (0 ng/L) or ecologically relevant low (52 ng/L) or high (496 ng/L) concentrations of amitriptyline. We found strong evidence of spatial learning across all treatment groups, with maze solve times and navigational errors declining over trials. However, males exposed to low and high concentrations of amitriptyline made 26% and 34% more errors, respectively, compared to control males. Female learning, by contrast, was unaffected by amitriptyline exposure, revealing sex-specific cognitive effects. Control males were more accurate than females, yet this advantage was lost under exposure and ultimately reversed at high concentrations, where males performed worse than females. These results emphasise the need to consider sex differences in cognitive responses when assessing the ecological impacts of environmental contaminants.

Small, genetically depleted populations of agricultural pests often face dual stressors: inbreeding depression and insecticide exposure. However, how these stressors interact to alter pest behaviour and population viability remains unknown. We here disentangle the independent and combined effects of inbreeding and sublethal insecticide exposure in Colorado potato beetle (Leptinotarsa decemlineata), using a multi-trait phenotypic approach. Outbred controls and inbred populations (two generations of sibling mating) were exposed or not exposed to sublethal insecticide (LC10 dose). We measured feeding behaviour, locomotor activity, reproductive output, and developmental success, and preserved individuals for ongoing genomic analyses. Results revealed striking sex-specific responses: males exposed to combined stressors showed 89% activity reduction, while females remained behaviourally unaffected. Counterintuitively, both sexes exhibited compensatory hyperfeeding (100% increase) under combined stress, with intermediate reproductive values rather than synergistic decline. However, emergence rates demonstrated true synergism, declining from 62.7% (controls) to 18.0% (combined stressors). These antagonistic and synergistic interactions create a paradoxical fitness landscape: reduced male dispersal coupled with intensified defoliation behaviour in both sexes. This finding suggests that population bottlenecks combined with insecticide application may inadvertently intensify pest damage through altered behaviour rather than reduced pest viability, fundamentally challenging current integrated pest management assumptions.

Migratory birds are known to be attracted to artificial light, contributing to collisions with buildings that kill millions of birds each year. However, birds can show diverse behavioural responses when they encounter light during nocturnal migration, including avoidance. Identifying the light characteristics, weather conditions, and other factors that change birds’ behavioural responses is key to minimizing the disruption of their migrations as artificial light at night continues to increase and older lighting technologies are replaced with blue-rich LEDs.

We conducted an experiment in Texas to understand how atmospheric conditions and the spectral properties of artificial light mediate bird response to light emitting diodes (LEDs). We used a BirdScan MR1 radar to measure migration traffic rate and flight height under three different light treatments – a blue-rich LED, a neutral LED, and a no-blue LED – compared to a dark treatment. We found no change in migration traffic rate among the treatments, possibly because attraction or avoidance occurred at a scale smaller than the radar’s 1-km detection radius. When we analysed flight height using a quantile regression, we found an important interaction between aerosolised particles in the atmosphere (primarily fog and mist) and light treatments. On clear nights, the lowest-flying migrants flew higher when the blue-rich or neutral LED was turned on, indicating avoidance of the light. On foggy nights, the lowest-flying birds flew lower during all treatments than during the dark treatments, indicating light attraction.

Migratory birds may expend substantial energy if they change their flight height every time they encounter a bright light. Using LED luminaires that emit less blue can reduce the disruptive effects of avoiding artificial lights on clear nights, but all LEDs are likely to attract birds on foggy nights. Reducing light pollution is crucial for protecting avian migrants from collisions.

Interactions between adults and juveniles play a central role in behavioral development, particularly when cultural skills are acquired early in life. In such cases, learning is often examined through the lens of maternal care, while the role of other adults and the broader social environment remains less well characterized. We studied adult–pup interactions surrounding a culturally transmitted foraging skill, pinecone opening in black rats. Observations were conducted in semi-natural captive colonies founded with wild-caught pinecone-opening adults. In a system previously described as involving strictly vertical transmission, we show that pinecone handling during the pup stage occurs in a socially rich context in which pups explore pinecones across diverse social settings and interact with multiple adults.

Our findings reveal that pups manipulated pinecones flexibly, alone, with other pups, and frequently in the presence of various adults, contrasting with adults’ predominantly solitary consumption when pups were absent. Adult–pup interactions during pinecone handling were frequent and predominantly positive. Such interactions, including direct mouth contact, involved multiple adults and juveniles rather than being restricted to mothers, and adults with higher affiliative interaction rates were more likely to forage alongside pups.

Taken together, these patterns indicate a clear developmental contrast in the social context of pinecone opening and highlight the involvement of non-maternal adults in juvenile-directed interactions around this foraging task. Juvenile exploration unfolds within a socially rich, cross-age environment shaped by tolerant adult engagement and broader patterns of adult affiliation. Observing the broader social dynamics surrounding a socially transmitted skill, rather than focusing on a limited social setting, is therefore crucial for understanding how cultural traditions persist and the pathways through which information can be transmitted.

Animals compete over often indivisible resources that vary across space and time. These contests are shaped by both competitor properties (e.g., size) and how individuals assess, or gather information about, resource value (RV). Perceived RV can shift with naturally-occurring changes in resource abundance, accessibility, and spatial distribution. However, most empirical tests of assessment theory examine dyadic contests over a single resource, hindering our understanding of how variation in resource abundance affects contest dynamics. Mantis shrimp exchange strikes with spring-powered appendages during contests over discrete, indivisible, and protective shelters called “burrows”; burrow availability can vary greatly across space and time. To test how variation in resource availability influences contest dynamics, we first staged dyadic 20-min contests between mantis shrimp (Neogondactylus bredinii) in environments where 3D-printed burrows varied in accessibility. We found the highest aggression when only one burrow was accessible and the least when both competitors could access separate burrows. We then staged days-long contests in automated tracking arenas, manipulating the ratio of competitors to burrows to mimic data from ecological surveys in the wild (average: 5 shrimp and 6 burrows in 0.5 m²). We reveal how patterns of aggression shift across environments that differ in RV by training algorithms to automatically classify contest behavior and track movement. By evaluating conflict in controlled dyadic contests and in more naturalistic automated tracking arenas, we show how conflict unfolds in ecologically relevant settings, offering insight into conflict in resource-structured environments.

Global migration and displacement increasingly restructure human social environments, altering patterns of sociality with potential consequences for survival and health. Forced displacement strongly disrupts social networks and familiar environments, exposing variation in social strategies under stress. Yet the fitness consequences of maintaining social ties during large-scale human displacement remain poorly understood.

This study leverages the unique natural experiment created by the mass evacuation of Karelians from Finnish territories annexed to the Soviet Union during World War II. More than 400,000 individuals were displaced, and although resettlement plans aimed to keep communities together, many chose to relocate individually. Using a linked historical dataset of over 59,000 evacuees, we examine how resettlement patterns and destination characteristics influenced survival and cause-specific mortality.

Specifically, we test 1) whether individuals who were relocated with their original community experienced different mortality outcomes than those who resettled independently, and 2) whether settling in municipalities with higher proportions of Karelians buffered or exacerbated mortality risks. These analyses integrate detailed demographic and socioeconomic data to disentangle the pathways through which displacement and social disruption translate into long-term health effects. We predict that individuals who maintained familiar neighbours or resettled in municipalities with higher concentrations of Karelians will exhibit lower mortality risks, particularly for causes of death associated with stress or social isolation.

By treating forced migration as a large-scale disruption of social structure, this study provides a rare opportunity to study how resettlement decisions and social connectivity shape survival outcomes. The relative uniformity of background characteristics in this population enables robust analysis of social network loss and fitness consequences.

Animals interact to communicate information and disseminate resources. Interactions are often examined as dyadic encounters, yet many interactions are high-ordered – with multiple individuals interacting simultaneously (e.g., an alarm call). Higher-order interactions may expedite the spread of knowledge and resources. In this talk I will discuss how the size of higher-order interactions influences the spread of food through trophallaxis, mouth-to-mouth food exchange, among colony-members of Argentine ants. We hypothesized that the size of trophallaxis groups, a higher-order interaction, will relate to colony hunger and will impact the behavior of foragers and food recipients. We found that trophallaxis groups were larger when colonies were hungry, resulting in rapid food dissemination to many individuals. However, feeding multiple individuals simultaneously in large high-order trophallaxis groups resulted in slower food intake by each recipient, because they had to share with others. Thus, when engaging in higher-order interactions in the context of food transfer there is a tradeoff between rapid food dissemination throughout a colony and food uptake by each individual worker. These findings show the importance of considering the size of higher-order interactions in social systems to account for both system level implications, such as speed of transmission, and the experience of interacting individuals. More broadly, the size of higher-order interactions may have important implications for tradeoffs between the speed and the amount, or quality, of information or goods that are being transmitted, and it may impact the response of individuals to the information they receive.

(1) PhD scholar, Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India - (2) Professor & Chair, Centre for Ecological Sciences, Indian Institute of Science, bangalore, India - (3) Professor, Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India

Sociality is an outcome of both benefits and costs, and can influence whether individuals associate with each other, including heterospecifics. Mixed-species bird flocks (MSFs) are a notable example of such social systems. MSFs enhance foraging benefits and reduce predation risk through mechanisms such as risk dilution, predator confusion, and oddity effect. Although observational studies have suggested that flocking species resemble one another in their plumage, colour similarity within flocks has not been systematically tested at a global scale.

In this study, we examine whether birds participating in MSFs are more similar in colour than expected by chance. We integrated global datasets on MSF composition with species-level colour proportion data to quantify pairwise colour similarity among species that are found in the same flocks. Using null-model randomisations and standardized effect sizes (SES), we tested whether observed flock-level colour similarity deviates from random expectations and whether these patterns vary with flock richness across continents.

Our results show that across continents, observed MSFs were consistently more colour-similar than null flocks, providing strong evidence that colour similarity is a feature of MSF assembly worldwide. This suggests a potential role of visual matching in reducing predation risk or improving cohesion. Contrary to expectations, this pattern did not vary systematically with flock size: colour similarity remained high across small, medium, large and extra-large flocks. We found that colour-based structuring operates broadly in MSFs, both across sizes and geographies.

Together, our findings provide the first global quantitative evidence that colour similarity contributes to MSF organisation, adding a new dimension to our understanding of social behaviour and community assembly in birds.

A growing body of work has quantified the adaptive value of social relationships. However, much of this work measures social relationships using a single season or year, resulting in a snapshot of an individual’s lifetime sociality. Because individuals often modify their behavior across their lifetime, during which time their social situation may change, temporal variation in an individual’s social relationship may also have fitness consequences. Quantifying the specific value of such within-individual plasticity in social relationships may thus be important, but has not been formally studied. Using 20+ years of data from a long-term study of wild, free-living yellow-bellied marmots (Marmota flaviventer), we identified widespread fitness consequences of within-individual social plasticity; individuals that expressed behaviors far from their average sociality were more likely to survive and reproduce. These findings may explain why studies using annual “snapshot” methods have found variable fitness consequences of social relationships in this system. We then explored potential environmental, internal, and social drivers of these important deviations from average social network position and found that environmental variation was, surprisingly, not associated with individual plasticity in network position. Together, this work may help explain the context-dependent value of social relationships and provide a unique approach that can be applied to other systems.

During development, males in male-dominant species often undergo a rapid period of upward mobility in social status, from ranking below all adult females to ranking above all adult females. This process of rank ascension is poorly characterized in most species. Using a 40-year behavioral dataset on baboons (Papio cynocephalus with natural P. anubis admixture) in Amboseli, Kenya, we test hypotheses about the pattern by which juvenile males attain dominance over adult females. First, because higher-ranking females are likely to have more social leverage and/or better body condition than lower-ranking females, we predict that males will ascend the female dominance hierarchy in a roughly linear fashion, from lowest to highest-ranking females. We also predict that the alpha females (the highest-ranking females in a group) will be the most challenging opponents to juvenile males. Second, we test the hypothesis that social and environmental conditions during infancy and juvenility affect the ability of males to successfully climb the social hierarchy. Both hypotheses were supported. Using data on 3867 dyads of 446 juvenile males and 324 adult females, we show that males take longer to win over higher-ranking than lower-ranking females, and males take disproportionately longer to dominate the alpha female in their group than all other adult females. We also show that several socioecological factors predicted slower ascension of developing males through the adult female hierarchy, including maternal loss in the juvenile period, and low maternal dominance rank. Notably, males begin to win over adult females long before they achieve adult female body size. Our results broaden our current understanding of male primate development as both a social and physical process, and suggest that alpha female baboons hold a particularly privileged spot in the female hierarchy.

Animals form societies of widely varying complexity, shaped by the diversity of relationships they maintain. While the social structure of large-brained and socially complex species—often characterized by differentiated relationships and multiple social levels—is increasingly well described, much less is known about the social organization of highly gregarious species. Starlings, for example, are renowned for their striking collective behaviours, yet the structure of the social preferences within these large winter flocks remains unknown. Theory suggests that, given a limited time budget, individuals should maintain a range of different types of relationships. In this study, we used data from a wintering population of PIT-tagged spotless starlings (Sturnus unicolor) detected by RFID-equipped feeders to construct high-resolution social networks that distinguish among different types of social relationships. We generated fortnightly networks, which included up to 450 individually marked birds, across three winters. Using recently developed egocentric network approaches, we show that, despite the apparent fluidity of winter flocks, individuals maintain a consistent, small set of close associates (2-5 individuals), a larger group of intermediate associates (11-18 individuals) and a broader tier of loose associates (23-34). This suggests that starlings maintain three social tiers, with the size of each tier matching the predictions from theory. However, the identity of an individual’s associates within each tier (with the exception of the future breeding partner) changes across fortnights. Starlings are therefore distinct from other multitiered societies in that social differentiation emerges from dynamic (rather than stable) inter-individual relationships and that these do not lead to the formation of distinct population-level network community structures. Our results provide novel insights into the dynamics of social relationships in highly gregarious species.

Social evolution has largely focused on interactions among conspecifics. By contrast, interspecific social behaviours are largely overlooked, despite their potential to help quantify the contribution of direct fitness versus indirect benefits in driving the transition to group-living. Mixed-species groups, which consist of individuals from two or more species that move and forage together, are found in avian assemblages worldwide. However, to date we still do not know how many species join mixed-species flocks or how the evolution of mixed-species group-living maps onto the evolution of conspecific social behaviour. Here we quantify the propensity to participate in mixed-species for 8,230 bird species. We show that mixed-species flocking is far more common and geographically widespread than previously thought. Further, we find that mixed-species social evolution is highly plastic and evolves as easily as, but independently of, single-species flocking. Our findings reveal the power of direct fitness benefits as a driver of social evolution.

Although group members generally benefit from stable social environments, various socioecological factors can induce permanent changes in group membership (social instability), which may negatively affect individual fitness. We investigated the factors driving group membership changes and the fitness consequences of social instability in common degus (Octodon degus). Using live trapping, telemetry, and DNA markers, we assessed social organization and reproductive output across four years. Degus show relatively unstable social structures, with groups varying in size and sex composition, and where individual group membership varies across seasons. Contrary to expectations, social factors (group size and proportion of females) did not influence the Jaccard Similarity Index (JSI, a measure of social stability). Maximum temperature had a marginally positive effect on JSI, suggesting greater social stability during warmer years. However, JSI was not related to reproductive output. For two years, we also collected behavioral data and network metrics, finding that JSI decreased with increasing eigenvector centrality—a measure of an individual’s connectedness within the network—indicating that more central individuals in the population experience greater social instability at the group level. Finally, males showed lower JSI than females, potentially reflecting an intersexual conflict of reproductive interests. Our findings suggest that climatic conditions can promote social stability in degus, though this stability does not translate into individual fitness benefits, implying potential population differences. Understanding factors influencing social instability and its consequences will deepen insights into social resilience and adaptability in degus and other social mammals facing environmental challenges.

Many reef fish species exhibit context-dependent shoaling, forming mixed species groups (MSGs) that offer potential foraging and antipredator benefits. However, empirical studies testing drivers behind group formation and benefits accrued remain limited. This study investigates the drivers of MSG formation in shoaling groups of herbivorous reef fish (traditionally interpreted as antipredator aggregations) across a predation gradient in the Andaman Islands, India.

Sixteen sites within and outside marine protected areas (MPAs) were surveyed using SCUBA diving. We tracked 653 MSGs via videography to quantify group size, species composition, duration, and foraging behavior. Predator abundance was estimated using baited remote underwater video systems, while resource availability and territorial competitors were enumerated along belt transects using photo quadrats.

Predator abundance, richness, and size were significantly higher inside MPAs when compared to adjacent fished reefs, yet MSG size and composition did not increase linearly with perceived predation risk. Since resource availability remained consistent across sites, a key alternative driver emerged: MSGs appear to form to overwhelm the aggressive territorial defenses of damselfishes. Several damselfish species farm and maintain algal gardens which they pugnaciously defend. By partaking in MSGs, herbivorous fishes gain access to nutrient-rich algal resources that are otherwise defended and thus inaccessible to solitary individuals.

These findings reveal that mixed-species grouping in reef fish is a dynamic strategy shaped by trade-offs between risk and resource access, challenging classical predator-centric views of shoaling behavior. Our study highlights how social decision making in the wild responds to changing predation and competition regimes and demonstrates that group formation may be driven as much by the need to access resources as by the need to avoid predators.

Sexual selection on animal genitalia has focussed largely on males, with the role of female sexual structures in mating interactions being largely neglected. Female genital traits have the potential to act as preference traits, determining successful mating and generating morphological divergence among isolated populations that results in mechanical reproductive isolation and speciation. Spiders are a model group for sexual selection studies. However, our understanding of their mating behaviour is highly biased towards araneomorph spiders, while the mating systems of mygalomorph spiders remains rudimentary at best. The Australian endemic burrowing mygalomorph spider genus Aname contains several short-range endemic species, characterised by low vagility and limited gene flow. For this reason, these spiders are a good model to test for the role of genital coevolution in speciation. We present detailed observations on mating interactions within and among populations of a single Aname species from south-western Australia. Mating interactions were recorded both in the lab, recreating a semi-natural setup, and in the natural environment of these spiders, through the use of a camera trap. A single Aname couple was frozen while in copula, and 3D images of the coupling genitalia were produced using micro-computed tomography (micro-CT). Our aims were determining whether differences in genital morphology and behaviour are drivers of speciation in this spider genus, and exploring the copulatory mechanics and sperm transfer process at a microscopic level of detail, through the analysis of the micro-CT scans. Moreover, in so doing we discovered a remarkable, novel male post-copulatory mate guarding behaviour, ‘Burrow Plugging’. Our data provide some of the first insights into sexual selection in mygalomorph spiders, and are an indication of a role for sexual selection in the speciation processes of this ancient taxa.

The potential role of haplodiploid sex determination in promoting the evolution of altruism and eusociality has been the subject of intense debate for over 50 years. Different theoretical models have suggested that haplodiploidy influences relatedness in a way that either does, or does not, make it easier for altruism to evolve. This debate over the ‘haplodiploidy hypothesis’ can only be resolved with a decisive empirical test that controls for potential phylogenetic bias. Here, we critically examine the current state of evidence for an adaptive link between haplodiploidy and eusociality, applying phylogenetically informed methods to ensure that statistical tests reflect independent evolutionary transitions. Using data from 5678 species, across all insect groups, we find no evidence that haplodiploidy favours an increased rate of eusocial evolution in insects. We show that this result is robust to: (a) different analytical approaches; (b) alternative ways of defining both eusociality and haplodiploidy; and (c) noise in eusociality assignments for uncertain clades. Our analyses suggest that previously reported associations between haplodiploidy and eusociality are likely to have been artefacts, false positive results primarily driven by a high transition rate to eusociality within the Hymenoptera. This high transition rate could be explained by any factor associated with that group, such as parental care, monogamy or the possession of a powerful sting.

Mating is one of the most important actions in the lives of sexually reproducing animals, and there is an extraordinary diversity in mating behaviours across species. Particularly, the duration of mating is staggeringly variable between and within species: mating can last from fractions of a second to many hours. However, the evolutionary drivers and ecological consequences of mating duration remain largely unexplored. Here we combine a phylogenetic, comparative approach with novel, empirical data to explore the drivers of variation in mating duration at both the macro- and micro-evolutionary scale. First, we performed a large-scale, systematic, comparative analysis to investigate the evolution of mating duration across internally fertilizing animals. Using a dataset of >3000 mating durations from over 700 species, we investigate evolutionary correlations between mating duration and body size, life history traits, and metrics of sexual selection. We identified in our comparative study that extremely fast matings and their evolutionary consequences are particularly understudied. To address this, we present novel behavioural data on the fastest mating species identified in our comparative analyses – a small, livebearing fish, the pygmy halfbeak (Dermogenys collettei). Using high-speed cameras, we capture the dynamics of sperm transfer and its relationship with both female and male mating behaviour in this species. Our data reveal that rapid mating in halfbeaks is associated with surprisingly frequent male mating failure that is negatively correlated with male age and experience and emphasizes the potential for female control over mating outcomes. By combining comparative data with an experimental study, we illuminate both the macroevolutionary evolutionary drivers of mating duration, as well as the evolutionary consequences of ultra-fast matings.

Scent marks are commonly used in social interactions in many mammals; yet, their role in mating systems are not well understood. Several lekking ungulates show elaborate scent-marking behaviour. Lekking male blackbuck antelope create dungpiles on their territories through repeated urination and defection. These scent marks are strikingly large, measuring up to 10 metres in diameter. New males taking over lek-territories continue to scent mark on the same dungpiles. I used observations and field experiments to test the role of sexual selection processes in maintaining these exaggerated scent marks on leks. First, I monitored the size of individual dungpiles over two seasonal mating peaks. Dungpile size varied widely across territories, and was most strongly correlated with female visits. Rates of scent-marking behaviour of males showed similar patterns. These results suggested that females use dungpiles as cues during mate choice. Since successive owners of a lek-territory continue to scent mark on the same location, dungpiles may carry information on the history of territory ownership and a male’s ability to deter intruders. This information may be used by females in mate choice. To test this hypothesis, I conducted a field experiment in which I measured the response of females to intrusions on male territories, simulated through an experimental addition onto territorial dung piles of a small quantity of dung from a strange male. Females reduced their visits to territories with simulated intrusions compared with controls. I carried out a similar set of experiments in which I measured the responses of territorial owners to simulated intrusions., under different conditions of male competition and female visits. Taken together, the findings suggest that dungpiles in lekking blackbuck represent a rare case of the evolution of an exaggerated scent ornament under sexual selection.

One of the most fundamental questions in ecology and evolution is how complex structures with novel ecological functions evolve. If selection has shaped traits for their current ecological niche, how do organisms establish novel niches or survive ecological changes? While mutation, drift and fluctuating selection may be important, we review the role that sexual selection has in ecological innovation using examples from birds, mammals, fish, insects, lizards and other groups. Sexual selection is a powerful evolutionary force that can generate extreme phenotypic diversity, even among closely related species. While sexual selection may push phenotypes away from a theoretical optimum shaped by ecological selection, it may at the same time drive and sustain the phenotypic variation necessary for animals to reach novel peaks in an adaptive landscape. Sexual selection can shape sensory physiology, drive niche exploitation, and foster ecological novelty. In this way, sexual selection may play a central role in allowing animals to break allometric developmental constraints, develop variation in behavior and neuro-muscular physiology and shape highly energy-efficient metabolic processes that lay an essential foundation for adaptation to novel or changing ecological selection pressures.

Individual cognitive differences are hypothesized to shape reproductive strategies through two distinct pathways of sexual selection: the cognitive ability influencing choosers' mate preferences, and cognitive traits being targeted by mate choice. However, the interaction between these two pathways remains poorly integrated, and the relative contribution of cognitive and morphological signals to mate preference is largely unresolved. Using budgerigars as a model, we investigated whether female cognitive ability influenced their preference for males of different cognitive levels, and which male traits (cognitive and morphological) predicted male popularity during short-term (4 hours) mate choice. We assessed performance across seven cognitive tasks in both sexes. A principal component analysis revealed that the first component (PC1) accounted for 42.7% of variance across tasks, representing a general cognitive ability. During mate-choice experiment, females allocated more time to males with greater body mass but lower cognitive ability. Moreover, while females with higher cognitive ability showed no preference based on male cognition, females with lower cognitive ability significantly preferred males with lower cognitive ability. These results indicate that under short-term interactions, mate choice is predominantly guided by morphological signal, whereas cognitive ability influences preference in a manner dependent on the chooser’s own cognitive level. Our study offers novel behavioral evidence for how sexual selection simultaneously operates on multiple trait dimensions of the selected sex. This advances a more integrated understanding of how both morphology and cognition shape mating decisions.

A popular explanation for the evolution of long-term monogamous partnerships is a positive effect of partnership duration on reproductive success. Yet, in many species that maintain extended pair bonds, no benefit of partnership length has been observed. For example, common terns (Sterna hirundo) are more likely to reunite with a previous mate than seek a new partner, yet pair bond duration has no effect on breeding success. An alternative explanation is that a previous partner is preferred because a mate-seeking bird has greater information about that partner. For instance, the ‘assured-age hypothesis’ suggests that when reproductive success increases with age, individuals benefit from choosing a mate they know. This is because mate-seeking birds have greater certainty of a previous partner’s age (the previous mate must be at least as old as the seeker’s memory of them) than the age of an unknown individual. We use an agent-based simulation informed by long-term breeding data from common terns to demonstrate that age-dependent reproductive success alone could drive the evolution of mate fidelity.

Male house mice (Mus musculus) emit complex ultrasonic vocalizations (USVs) during courtship and mating, and though many studies indicate that these signals provide reliable indicators of male genetic quality, it is not known whether they influence copulatory success. We recorded the behaviour and vocalisations of pairs of house mice (F1 of wild-caught M. musculus musculus) over two days and analyzed their vocalizations during five phases of courtship and mating. We detected and classified > 53,000 vocalisations and ca. 90% of these were USVs, which are emitted mainly by males, whereas 10% were broadband vocalisations (BBVs) or 'squeaks', usually emitted by females. The mice altered the composition and repertoire of USVs at each stage of courtship. During early courtship, they mainly emitted simple, continuous USVs, whereas once males began mounting females during late courtship, they emitted more complex, discontinuous types of vocalizations, and USVs with harmonics and BBVs with spectral nonlinearities. Vocal emission was closely associated with male mating behaviour and peaked in rates and complexity just before males approached a female and attempted mounting. USV bouts began earlier and contained more complex syllables whenever a mating attempt ended in a copulation. As courtship progressed, USV and BBV emission became highly synchronised, as with duetting songbirds. We found several differences in the vocal repertoire and acoustic features between the 14 pairs that successfully copulated (with ejaculation) compared to the 22 pairs that failed to mate. USV emission was positively correlated with male sexual behaviours, especially among copulating mice, suggesting that the effect of USV emission on male mating success depends on their sexual behaviour, and vice versa. Our results show that the courtship vocalisations of house mice are complex and highly dynamic and provide the first evidence that they correlate with and predict male copulatory success.

Inequalities in reproductive success among females and males shape natural and sexual selection, as well as genetic diversity. A key mechanism influencing reproductive inequality in humans and other animals is the social inheritance of privilege. Using a 29-year dataset spanning eight generations and including 3,240 individuals from eight clans of spotted hyenas (Crocuta crocuta), a species in which social status is maternally inherited, we show that inheritance of privilege associated with high status not only shapes reproductive inequality but can reverse its typical sex bias. As in most polygynous species, reproductive inequality was lower among females than males when estimated on an annual basis. When measured across multiple generations, inequality increased in both sexes but disproportionately so among females. This effect was strong enough to reverse the sex bias in favor of females after a single generation, intensifying intrasexual competition among females. Within just a few generations, most individuals descended from top-ranking female ancestors, reflecting how maternal inheritance of privilege concentrates reproduction in a small number of females. These effects, in turn, shape male mating strategies and patterns of genetic contribution over time. Overall, our findings demonstrate that social inheritance of privilege can substantially elevate reproductive inequality across generations, remodel selective pressures, and contribute to the evolution of sex differences in competition and reproductive strategies.

Behavioural traits such as exploration, risk-taking and boldness constitute the first line of response to environmental challenges and are critical in shaping how individuals use space and interact with conspecifics. Consequently, it is hypothesised that these personality traits influence mating decisions by mediating not only who individuals choose to mate with, but also how individuals choose their mates (e.g. how choosy they are), but we currently lack a general, cross-species pattern in the literature. To understand the impact of personality difference on mate choice, we combine a controlled experiment on wild house mice with long-term data from fourteen populations living in semi-natural enclosures. In the controlled experiment, we quantified the exploration and risk-taking of 61 individuals before conducting mate-choice tests. Preliminary results show that explorative females were less selective of their mates, while there was no effect of exploration or risk-taking on mating assortativity. We are following up on this experiment by analysing data from over 1000 females living in fourteen semi-natural enclosures to assess whether the mating preferences in the experiment translate to realised mating outcomes. Based on results under the controlled, experimental mate choice test, we expect that more explorative females will be less selective and will mate with more males regardless of the males’ personality, consequently showing higher rates of multiple paternity. Our approach synthesises experimental and observational evidence to clarify how personality traits affect mating decisions; a crucial social process in humans and non-human animals with important evolutionary consequences.

Dwarf seahorses (Hippocampus zosterae) are a cryptic species displaying filamentous appendages, known as cirri, which have been historically assumed to have evolved for camouflage purposes in other species of seahorses. To investigate potential patterns in cirri presence in H. zosterae, photos from monthly sampling over a year-long period in Tampa Bay, Florida were analyzed to deduce which environmental parameters could be correlated with cirri. Cirri presence on wild caught seahorses was quantified using a scoring system of cirri on three head areas and one body area that summed to an overall cirri score for each fish. Preliminary results indicated that females had more cirri than males, and that fish with more cirri were present during the wet season, coinciding with the breeding season of H. zosterae. The sexual dimorphism identified in this trait for dwarf seahorses led to a hypothesis centered around cirri’s potential role in mating preferences. To determine if cirri are a sexually selected trait, wild seahorses were brought into the laboratory for mating trials consisting of three size-matched seahorses: a male, a highly ornamented female, and a less ornamented female. We developed a novel methodology for photographing female seahorses to measure cirri counts, length, and surface area and documented the potential loss of cirri in a captive setting. Our genetic results confirmed the highly ornamented female was chosen in 17 out of 19 trials, supporting our hypothesis that this trait serves as a sexually selected trait with males showing a mating preference for females with greater cirri. Drastic cirri loss was recorded for females over 21 days in captivity, prompting new hypotheses that cirri function as a condition-dependent trait involved in mate signaling, and may serve as an indicator of seahorse health and survival.

For many animal behaviours, timing is everything. This is especially true during early development. In birds, newly hatched chicks are dependent on parental provisioning, vulnerable to predators, and susceptible to temperature stress. Given this intense selection pressure, it is expected that bird embryos should time their hatching behaviour so that they emerge from the egg at a time of day that optimises parental care capacity, predation risk and microclimate conditions. Precise hatch timing should be possible, since bird embryos are sensitive to daylight cues and have internal time-keeping mechanisms. It has further been shown that insects and fish hatch at non-random times of day, with emergence times linked to daily light cycles and influenced by species ecology. However, surprisingly, whether birds hatch at non-random times of day is almost entirely unexplored. Here, we investigate the behavioural ecology of precise (daily) hatch timing in wild birds. We first establish whether hatch timing is non-random using nest camera videos of hatching birds across diverse species (>30 families) sampled worldwide. We compare nocturnal and diurnal species, as well as altricial chicks that are highly dependent on parental provisioning, and precocial chicks that leave their nest shortly after hatching. Our project establishes whether bird embryos time their hatching behaviour according to natural daylight cycles and explores the selective advantages of hatching at certain times of day (or night). Our results have implications for designing captive breeding programs and for understanding the potential effects of artificial light at night on bird hatching behaviour.

Avian tool use has been suggested to have a strong stereotyped component, as birds may have behavioural predispositions to handle elongated stick-like objects from nest building and food caching. However, parrot tool users without these predispositions such as Goffin’s cockatoos nonetheless demonstrate flexibility. Goffins dexterously manipulate the tools inside their beaks with their flexible thumb-like tongue and their mandibles. In doing so, they can achieve grip types that functionally assimilate primate’s precision- and power-grips. During tool use, they develop individual techniques which they adjust to environmental conditions. Surprisingly, individual Goffin’s cockatoos use similar techniques when using stick tools to extract food pulp from hard to open fruits such as the Wawai (Sea Mango) and Ketapang (Sea Almond). We hypothesize that the properties of the fruit constrain possible movements with the tools and thereby dictate similarities in technique even if the behaviors are individually innovated. To test this experimentally, we provided artificial fruits that mimic specific aspects of the Ketapang and the Wawai to our population of captive Goffins in lower Austria. The Goffins were able to handle these small apparatuses freely using their feet and could use a small stick-tool to extract the food pulp using their beaks. During testing, birds were tracked using the machine-learning tool Deeplabcut to enable detailed descriptions of the dexterity within their movements while using tools. We predicted specific techniques for each artificial fruit type. Results may highlight how target properties could constrain tool use technique as well as Goffin's flexibility in response to changing environmental conditions. We also describe the temporal development of the bird’s techniques as well as their management of spatial relations during the tasks.

Amphibians represent the most at-risk vertebrate taxon, and are vulnerable to multiple, complex, and interacting anthropogenic threats. However, tadpoles, their larval stage, are relatively neglected in conservation research, with little known about the behavioural impacts and welfare implications of interacting environmental stressors. Whilst increased temperatures generally beget an increase in tadpole activity budget, and the perceived presence of predators causes it to decrease, the impacts of increased temperature and perceived predator presence have not been previously studied in combination, as they would most likely be experienced in the wild. Thus, the consequences of any interaction between these seemingly opposing forces were previously unknown. Here, I investigate the effects of increased temperature, perceived predator presence, and an intense disturbance event on larval Alytes muletensis, an endangered European anuran and EDGE species typified by a prolonged larval phase and threatened by climate change and the invasion of a novel predator species. I use an experimental approach to measure activity before and after a disturbance event in increased vs. ambient conditions and in the presence or absence of a chemical predator cue. I find that tadpole behaviour changes following a disturbance, characterised by decreased activity compared to a control, indicting that disturbances to tadpole habitats elicit decreased foraging and social behaviour, impacting their welfare. I also observed an unexpectedly rapid and reversible change in body colour, a possible predator avoidance strategy. This research not only sheds light on the evolution of stress responses in larval anurans, but provides a robust case study for the monitoring of larval behavioural welfare indicators with the intention of informing amphibian conservation practices and ex-situ management protocols in the future.

Ruffs (Calidris pugnax) exhibit three alternative reproductive tactics (ARTs) that are genetically determined and maintained for life. 'Independent' males compete aggressively for a display territory, while two other tactics (‘Satellites’ and ‘Faeders’) are non-territorial and opportunistically capitalize on the investment of Independents to secure copulations. In particular, Satellites co-display submissively with Independents and surreptitiously sneak copulations when the occasion arises. Prior observations indicate a degree of plasticity within each tactic, yet the extent to which these ARTs can adapt to changes in their social environment remains unclear. In this study, we examined the effect of experimentally altering the social environment on the expression of courtship and aggressive behaviour in a captive population of ruffs. We kept males either in mixed or pure morph groups together with females and recorded their aggressive, courtship, co-display behaviour using a synchronized video camera system within the experimental arenas. Specifically, we assessed whether separating males by morph influences aggressive and co-display dynamics, potentially causing sneaker males to adopt a behavioural repertoire that is typical of Independents, in the absence of dominant competitors. The ultimate aim of this study is to shed more light on the interplay between genetic and social factors on the evolution and maintenance of ARTs in the ruff.

Home range and movement studies are valuable for understanding individual responses to environmental conditions, particularly for species in arid environments that must balance energetic demands with thermal constraints. Among raptors, such studies disproportionately focus on large, charismatic species, creating a significant knowledge gap for small-bodied species. Yet the latter typically have limited capacity for thermal buffering, particularly in arid environments. We attached miniaturized GPS tags to Africa’s smallest diurnal raptor – the Pygmy Falcon (Polihierax semitorquatus) – to obtain movement fixes of 13 individuals during the chick-rearing phase of the breeding cycle in the Kalahari Desert. We aimed to delineate the home range and determine how the likelihood of movement and distance traveled varied with time of day and temperature. We obtained an average of 296 GPS locations per individual. Our autocorrelated kernel density home range analysis showed the falcon’s breeding home range averaged 0.93 km² (range = 0.19 – 1.28 km²). Falcon movement within this home range showed a bimodal pattern through the day, peaking twice at 10:00 and 16:00. However, a unimodal relationship with temperature emerged: falcons were three times more likely to move when temperatures were the lowest than the highest and traveled shorter distances when temperatures peaked above a 25°C threshold. The home range estimates reveal a highly localized spatial foraging strategy for this species during breeding, which establishes a crucial baseline breeding home range size for small diurnal raptors. The falcon’s movement patterns demonstrate that thermal regulation primarily drives movement ecology in desert raptors. Furthermore, these patterns reveal the critical thermal limits for this small desert raptor, emphasizing the necessity of thermally buffered habitats to improve species resilience in the face of climate change.

Environmental cues provide important information in the survival and reproduction of both plants and animals. The ability to use these cues to anticipate food availability would allow animals to optimise their life history strategies in a changing environment. The quality and timing of tree seed production is changing as the climate warms, shifting a key food resource for woodland birds. In great tits, the overwinter survival of fledglings is strongly linked to the amount of beech seeds (mast), but adult birds can not directly assess this during the breeding period but it can potentially be predicted from summer temperature cues and mast quantity in the preceding year. Using a series of long-term datasets from across Europe on great tits and beech masting, we tested: i) whether birds adjust their reproductive strategy in anticipation of mast years ii) whether this adjustment is in response to mast quantity and temperature cues from the preceding year and, iii) whether older birds, which have access to cues from the preceding year, showed stronger adjustments in their reproductive strategy. Birds had larger, heavier broods ahead of a mast year, and smaller, lighter broods in years following a mast, which is in line with our predictions. There were small but important effects of summer temperature the preceding year and adult age on both brood size and chick mass. Recent work has shown that the previously predictable relationship between summer temperature cues and beech masting is breaking down and beech seed production is becoming less variable, and less synchronised. Understanding the reliance of tits on cues of future resource availability is therefore essential to assess the potential mismatch in reproductive strategies between species under a warming climate.

Seasonal coat color (SCC) change is a key adaptation in snow-dependent species such as mountain hares Lepus timidus, allowing them to camouflage and survive in dynamic environments. However, with unpredictable seasonal variations, the timing of this trait may become mismatched with environmental conditions, thereby increasing predation risk. In this study, we aimed to quantify the seasonal timing of coat-color molt in mountain hares (L. timidus ainu) using bycatch camera-trap data deployed in Takino Suzuran Hillside Park, Hokkaido, in 2024. To quantify the correlations between snow cover and coat-color phenology, we fit separate Bayesian multinomial logistic regression models for spring and autumn. Our results show distinct seasonal molt timing, with molting peaks recorded in mid-April and mid-November. In spring, snow cover strongly influenced the probability of mountain hares being in a white coat, with no significant impact on autumn molts (brown-to-white). We also quantified coat-color mismatch, which occurred particularly in autumn, with no mismatch detected in spring. These findings highlight the need to better understand molt phenology of coat-color-changing species in response to local environmental variation, while also demonstrating the value of repurposing management-focused wildlife bycatch data for ecological and conservation research.

Our behavior is shaped in part by our previous experiences and our current reality, which do not always align. Thus, individuals face the challenge of determining how long past information (such as the level of predation risk) should be retained and when it is no longer salient. Information from different time points may be combined in several different ways. Individuals may do so additively, where repeated information results in progressive exaggeration of a behavioral phenotype. Or they may develop threshold responses, where an exaggerated phenotype is expressed only after a certain amount of information is gathered. Though theoretical models of information integration are well defined, empirically investigating which of these mechanisms animals use can be challenging as it requires longitudinal data after repeated exposures. To address this, we investigated how varying amounts of short-term high risk exposure (simulated predation) altered individual behavioral phenotypes and tracked how long these effects lasted. We used the clonal Amazon molly (Poecilia formosa), allowing us to pinpoint experiential effects as these animals are naturally genetically identical. Individuals experienced one of the following treatments: control (no predation), low risk (one simulated predator chase), medium risk (three chases), or high risk (5 chases). We repeatedly measured space use and foraging behavior as a proxy for risk perception before, during, and after the final chase event to determine the shape and durability of the fish’s risk perception. Preliminary results suggest that space use behavior can be altered for several days post risk exposure, providing support for the idea that individuals use past information to inform their current behavior. While we are still ascertaining the exact pattern of risk perception responses, the outcome of this study will offer key insight into how animals weigh instances of risk throughout their lives.

Although primates are typically considered arboreal, the extent of tree use varies widely. Among great apes, gorillas are the largest-bodied and most terrestrial, yet interspecific variation exists. Mountain gorillas are primarily ground-dwelling folivores, while western lowland gorillas climb more frequently and rely more heavily on fruit. We investigated arboreal behavior in wild western lowland gorillas (Gorilla gorilla gorilla) to assess how sex, individual identity, activity type, tree height, food type, and seasonality shape vertical space use. We analyzed 2,398 h of observational data collected from a habituated one-male, multi-female group at the Mondika Research Center, Republic of Congo (2004–2005). Western gorillas spent significantly more time above ground and used higher substrates than mountain gorillas in the Virungas. Females were more arboreal than the male and engaged more in non-foraging behaviors, such as resting and traveling while in trees. Tree height use varied by sex and season, with the male unexpectedly using higher strata. Seasonal shifts in resource availability strongly influenced vertical space use and diet, revealing distinct sex-specific and individual patterns. These findings indicate that western gorilla arboreality is flexible and shaped by habitat structure, resource availability, and individual traits and may represent an adaptive response to environmental variability. Our results highlight the importance of incorporating complex climbing structures into captive enclosures to support the health and welfare of western gorillas, the only gorilla subspecies in zoos and one particularly prone to cardiovascular disease.

The appearance of colours in nature is strongly influenced by lighting conditions. This is especially true for glossy objects, which are characterised by reflecting a high proportion of incident light at the mirror angle. This produces high-intensity white reflections in direct sunlight but these will appear muted and dull on cloudy days. These high-intensity reflections can contrast strongly with the surrounding environment and are often perceptible from long distances. Therefore, glossiness can be an effective long-distance cue of a shiny resource, such as conspecifics or a food source, but only if the resource is in direct sunlight. Despite the substantial impact of lighting conditions on visual scenes, few studies have quantified how weather conditions impact visual behaviours, and none have investigated the impact on glossy colours. Here, we investigated whether jewel beetles (Family: Buprestidae) use glossiness as a long-distance cue of aggregations of glossy conspecifics, and the impact of weather conditions. In the natural habitat of jewel beetles, we documented beetle attraction to glossy and matte interception traps. As predicted, male beetles were more attracted to glossy traps than matte traps, but only on sunny days. To further interrogate the function of gloss attraction, we documented beetle behaviour towards glossy and matte replica beetle models. Beetles were more likely to approach glossy replica beetles than matte replica beetles, and often attempted to mate with the replicas. Our results indicate that jewel beetles use glossiness as long-range and short-range cue of potential mates, but only in conditions that will maximise the glossy appearance. This demonstrates the importance of considering environmental conditions when assessing functions of animal colouration.

Heatwaves, and other climate extremes, impact ectotherm survival. Critical thermal limits are established viability thresholds when studying the impact of climate change on natural populations. Thermal fertility limits of species have been proposed alongside critical thermal limits, to better assess the sublethal effects of rising temperatures on species persistence. However, mounting evidence shows that extreme temperatures produce variable effects on reproductive traits depending on species and context. To explain this variation, and understand how sublethal effects affect ectotherms, we need to integrate physiology, ecology and evolution to be able to predict future species persistence under climate change. Here, we point towards the key role of microclimate ecology in driving this variability. Temperature extremes may affect fertility in nature interacting with microclimates, sexual selection and conflict in insects and, in turn, affecting population growth and persistence.

Animals typically learn associations when a neutral stimulus, the conditioned stimulus (CS), precedes a reward or negative outcome, the unconditioned stimulus (US). However, in other cases, ‘backward conditioning’ takes place where animals can learn about the CS after experiencing the US, such as when animals learn a predator-related stimulus after unexpected attacks. In nectar-foraging bumblebees, floral stimuli (CSs) are better learned when they precede sugar rewards (US), but bees still show evidence for backward conditioning when they ‘turn back and look’ at flowers after leaving. However, bumblebees collect pollen as well as nectar from flowers, which they often pack into corbiculae while still facing the flower they just visited, presenting the opportunity to attend to floral features for longer. As such, the optimal timing of learning floral stimuli for pollen may differ from that of nectar. Using artificial flowers containing micro servo motors that allow control of the timing of color presentation, we aim to compare the timing of learning floral stimuli for nectar versus pollen foraging bumblebees. Data collection is ongoing, and we expect to present preliminary results.

02 02. Sexual selection

While foraging individuals represent the expected value of reward opportunities and use this information to guide their decisions. Such value judgements are crucial for food-caching birds like the Eurasian jay (Garrulus glandarius) that regularly decide between a multitude of their own caches to retrieve, but also steal the caches of other birds. While studies have shown that corvids are sensitive to the content and perishability of their own caches, less is known about the representations they form of caches hidden by other individuals, and how they integrate these factors to optimise foraging. In this study, we used a violation-of-expectation paradigm to investigate whether jays are sensitive to the quantity of rewards they observed being hidden by an experimenter. We hypothesised that when jays’ expectations were negatively violated, their behavioural responses would reflect the absolute magnitude of the discrepancy between their expectation and the outcome. Subjects were presented with two conditions in which hidden reward was consistent with their expectations (expect 5, get 5; expect 1, get 1) and three conditions in which food was manipulated to negatively violate their expectations (expect 5, get 0; expect 1, get 0; expect 5, get 1). Overall, Jays spent more time inspecting the baited cup and were more likely to inspect an alternative cup in violation compared to control conditions. Consistent with our hypothesis, responses were stronger in expect 5, get 0 than in expect 1, get 0, but did not differ from controls in expect 5, get 1, though subjects experienced a large absolute discrepancy in reward quantity in this condition. Overall, our results show that jays are sensitive to quantities of items that others have hidden, and suggest that behavioural responses to expectancy violation may be mediated by both the magnitude of discrepancies and the utility of observed outcomes.

Research over the past decades has identified consistent variation in how individuals learn in humans and a few model organisms in the lab, which can be characterized as alternative learning styles. Studies of animal cognition have highlighted interindividual difference in learning performances in a wide variety of non-model species in the wild, but the existence and role of learning styles in wild animals have been largely ignored so far. One reason for this gap is likely because of the difficulty to assess the process of learning over time outside of closely controlled, captive settings. To overcome this challenge, we deployed 16 automatic feeders (OpenFeeders, OF) designed to test associative learning in 4 populations of free ranging great tits (Parus major) in the French Pyrenees during winters 2018 to 2021. The OF delivers seeds to RFID tagged birds that perch only when a specific visual cue (colour) is displayed and records both correct and incorrect arrivals to the feeder for each individual. We extracted learning curves from 287 birds using the shift of accuracy (rate of correct perching) across a one-month period. We then modelled 3 distinct learning styles that represent different ways to learn based on existing literature in lab organisms (no learning; “fast reached plateau” exponential learning; “slow beginning then fast reached plateau” sigmoidal learning), used a comparative approach of goodness of fit to observed patterns to identify which type of learning style a bird is using, and explored potential factors driving these differences (age, sex, population elevation). Finally, we measured the repeatability of learning styles on the 49 and 12 birds tested 2 or 3 years respectively. Together, this work provides the first investigation of learning styles in a wild organism and opens up new questions about how organisms facing environmental change might cope as well as how variation in cognition can evolve in wild populations.

The maintenance of cultural traditions involving complex extractive foraging, such as the pine-cone opening tradition in black rats (Rattus rattus), may impose significant cognitive demands, including the ability to tolerate delays before rewards are obtained. This capacity has been suggested to play an important role in rats’ skills acquisition, as the initial stages of cone opening involve removing rows of seedless scales.

We tested whether exposure to this cultural tradition is associated with enhanced delay tolerance, by testing the performance of wild rats from populations with and without pine-cone opening in a qualitative delayed-reward paradigm. Individuals were required to forego an immediate, low-value reward to also obtain a higher-value reward after a delay. Delay durations were increased incrementally from 30 seconds to 15 minutes. We quantified the maximum delay tolerated and analyzed rats’ choices and response latencies.

Contrary to our predictions, rats familiar with pine-cone opening did not differ from naïve rats in delay tolerance. Nonetheless, individuals across both populations were capable of waiting for long delays to obtain the higher-value reward (averaging 180 seconds with some exceeding 300, far surpassing typical lab rat performance of 30–60 seconds). As delays increased, rats consumed rewards more quickly and prioritized the high-value option more consistently, which suggests that rewards were valued more highly as the time-cost of obtaining them grew.

Overall, our results do not support population-level differences in delay tolerance associated with cultural background. However, the pronounced delay tolerance observed in black rats suggests that sustained tolerance for delayed rewards may represent a fundamental cognitive prerequisite for the emergence and persistence of labour-intensive behaviors such as pine-cone opening. Such capacity likely contributes to rats’ ability to exploit variable resources and adapt to diverse conditions.

Animals are supposed to forage optimally, however seemingly irrelevant options, such as highly preferred but unavailable “phantom decoys”, can shift decisions by captive animals in simplified contexts. But do decoys influence wild animals choosing complex foods in the real world? We tested this question with free-ranging swamp wallabies, a mammalian herbivore ecologically similar to browsing deer. We offered wild wallabies’ pairs of native plants — a tree seedling (high in plant chemical defences) and a grass (high in structural defences) — with or without a phantom decoy. The phantom decoy dominated (had higher value) either the available tree seedling or grass to test whether we could shift choice in opposite directions. We used either a strongly (“far”) or weakly (“close”) preferred decoy to determine whether the difference in relative value affected the decision outcome. We found that the “far” decoy consistently pushed wallaby choices away from the dominated plant corresponding with the reactance effect in humans. Compared with the absence of a decoy, wallabies were more likely to choose grass when the phantom decoy dominated the tree seedling and were less likely to choose the grass when it was the dominated option. In contrast, the “close” decoy had no effect on wallaby choices. Our findings provide crucial evidence that phantom decoys can shift real-world choices by foraging animals. From a cognitive perspective, the fact we could shift choices in either direction — depending on the attributes of the decoy — shows the power and generality of the decoy effect. From an ecological perspective, such a strong influence from a present but unavailable option contradicts, and therefore has important implications, for classic foraging ecology.

Recognising individual partners is a crucial survival challenge linked to cooperative and prosocial behaviours. Such behaviours have been observed predominantly in animals with complex cognition and social systems, such as primates and dolphins. Among birds, parrots stand out for their complex cognition and propensity for cooperativeness. Some indications suggest that Psittaciformes can differentiate between their conspecifics. This study investigates Psittacus erithacus, a species known for its cognitive abilities, to determine its capability of recognising conspecifics using vocal cues alone. We employed a playback experiment using the habituation/dishabituation paradigm, comparing individuals with neutral social affinity. Our findings indicate that the subjects could effectively discriminate non-kin group members even in the absence of strong social closeness.

Contrary to rational choice theory, adding an inferior option to a choice set can alter preferences among the original options. This phenomenon, known as the ‘decoy effect’, is probably the best example of how context can affect decision-making. Although it has been most studied in humans, to understand how product features affect consumer choice, it is also relevant to understand how prey community composition can shape predator preferences. Here, we test for a decoy effect in great tits (Parus major) in the context of predation on chemically defended prey. In a novel world experiment, wild-caught birds were trained to feed on artificial prey that varied in taste (chemical defence) and size. We assessed prey preferences and examined whether the addition of a third, inferior (i.e. less palatable or smaller) and supposedly irrelevant option altered these preferences. Our study brings new insights into how the distribution and availability of prey can affect predator decision-making and thus prey fitness under predation pressure.

Invertebrate cognition research has been dominated by studies on (social) insects, yet spiders—despite being almost entirely solitary—are miniaturized bio-computers that achieve surprisingly rich cognitive performances with “economically” far fewer neurons, in many cases paralleling those of vertebrates. With a neural architecture that lacks both insect mushroom bodies and any vertebrate-like frontal cortex, spiders offer a unique opportunity to understand alternative evolutionary pathways to complex cognition.

Here we synthesize current knowledge of spider cognition and compare it with insect cognition across four dimensions: (i) Demonstrated capacities, such as selective attention, strategic planning, problem-solving, tool use, numerosity; (ii) Emerging or plausible traits, including self-control/delayed-gratification, face or self-recognition, unsupervised learning, copying behavior; (iii) Evolutionarily constrained traits such as knowledge transmission, kin recognition and altruism; and (iv) Spider-specific innovations, particularly silk-based problem solving and manipulation as forms of alternative/extended cognitive. Using Dennett’s four-creatures framework (Darwinian, Skinnerian, Popperian, and Gregorian), we evaluate which cognitive strategies spiders truly deploy.

This synthesis reveals that spiders often surpass the Skinnerian level and, in some taxa, approach Popperian problem-solving, while their use of silk-based sensing may constitute a rudimentary form of Gregorian extended cognition. By integrating neural architecture, ecological constraints, and behavioral evidence, we argue that spiders, despite their predominantly solitary lifestyles, challenge long-standing assumptions about the evolution of complex cognition outside social context.

Studies investigating fish cognition in the wild remain scarce due to methodological and financial constraints, as well as limited control over exogenous factors and unpredictable weather. Yet advancing in this area offers invaluable insights into the ecological relevance of decades of laboratory findings on fish cognition and has the potential to improve management and restoration efforts, especially in the face of rapid environmental change. In this study, we investigated how the loss of structural habitat complexity affects the cognitive abilities of humbug damselfish (Dascyllus aruanus). Fieldwork was conducted on One Tree Island, a protected, tourism-free coral cay in the southern Great Barrier Reef, from September to October 2025. Coral cover around the island dropped to just 30% during the observation period mainly as a result of coral bleaching and Cyclone Alfred. Cognitive flexibility and inhibitory control were assessed in the field, employing a reversal learning and a barrier task in groups of humbug damselfish inhabiting reef patches of varying habitat complexity. However, a variety of other reef fish also consistently participated in our experiments. Cognitive flexibility enables individuals to adapt their behavior in response to shifting environments, whereas inhibitory control suppresses immediate impulses in favor of behaviors that yield longer-term benefits. We hypothesized that reef fishes from more complex sites would express higher cognitive flexibility and inhibitory control than individuals from less complex sites. In fishes, increased habitat complexity is associated with relatively larger brains and brain regions such as the telencephalon and cerebellum, thereby augmenting advanced cognitive functions. Understanding how habitat complexity influences reef fish cognition in the wild is crucial, as cognitive abilities may play a key role in determining individual survival and species persistence under rapidly changing environmental conditions.

How do insects form complex representations of visual objects in their environment? The field of Statistical Learning has recently highlighted both shared features and key differences in the way humans and honeybees process multielement visual scenes. Bees, like humans, spontaneously encode the frequency of occurrence of visual elements. They are also able to group elements that repeatedly co-occur, to the point that objects composed of multiple elements are more readily recognised than individual elements composing these objects. This process of grouping several elements as a single memory unit is known as chunking. Chunking is a crucial cognitive, mostly implicit, process. It has been widely observed in vertebrates – including humans – and allows them to compress information and bypass memory limits during learning.

However, in vertebrates, chunks themselves have been systematically shown to have limits in the number of items that they can comprise. In bees, size limits of chunks, as well as the influence of other parameters, such as the overall number of elements to memorise, that may constrain the formation of a unified visual representation, remain unknown.

Using a training paradigm emulating a real-life foraging scenario, we investigated, in a series of experiments, the parameters influencing the formation of visual objects in honeybees. Our findings provide insight not only into the perceptual learning constraints that shape honeybee behaviour, but also into the evolutionary history of this fundamental cognitive function shared across vertebrates and invertebrates.

02 02. Sexual selection

An animal possessing reversal learning ability is capable of unlearning a previously learned association between a stimulus and a reward and learning a new contingency. It is a form of behavioural flexibility which can be advantageous in changing environments. Serial reversal learning occurs when an animal’s performance improves over repeated reversals of contingencies. In this study, we tested the serial reversal learning ability of great tits (Parus major) in an aviary experiment where they could choose between two laterally positioned locations marked with different symbols. One of the two locations contained a hidden food reward, and the side that was rewarding and unrewarding was reversed several times for each bird. We divided the learning process after each reversal into two phases, the perseverance phase and the new learning phase, quantified by the number of visits before and after the first visit to the newly rewarding location respectively. We found that the length of the perseverance phase significantly decreased over repeated reversals. However, there was no corresponding decrease in the length of the new learning phase. This suggests that perseverance and new learning are separate cognitive processes, and that the former may be less challenging than the latter. Initially the birds also showed a colour preference for yellow over blue, but this did not affect their reversal learning ability. The high behavioural flexibility of great tits may help explain their success in exploiting challenging environments.

Human-induced climate change is dramatically altering the global thermal environment. Recent decades are characterised by rising summer temperatures and increasing frequency, duration, and intensity of extreme heat events (i.e., heatwaves), with further intensification of heatwaves predicted for the coming decades. The range of temperatures that organisms can physiologically tolerate strongly influences their spatial and temporal distributions, thus heatwaves can threaten population persistence. Thermal tolerance studies, however, have typically focused on how extreme heat impacts survival, ignoring potentially critical sublethal impacts of temperature extremes. Notably, recent evidence suggests that high temperatures can impact fertility traits, such as the number and viability of sperm and eggs, which can in turn lead to infertility and reproductive failure. Ultimately, thermal limits to reproduction rather than lethal temperature limits may dictate species distributions. Thus, heatwaves may have important wider impacts on biodiversity.

Although evidence for negative effects of temperature extremes on fertility traits is accumulating, what is needed now is a comprehensive assessment of how extreme heat impacts primary sexual traits critical to fertility across a broad range of taxa. We conducted a systematic review and meta-analysis to evaluate the effects of temperature extremes on sperm, egg, and gonad traits in non-human animals. We screened over 1600 recent studies and incorporated data from an existing systematic map examining the relationship between temperature and reproduction. Our meta-analysis revealed widespread negative effects of high temperatures on gamete quality; for example, in endothermic animals, high temperatures were linked to declines in sperm concentration and motility. These findings suggest that heatwaves may threaten the reproductive health and fertility of wild animal populations and thus pose a ‘hidden’ threat to biodiversity.

Spiders’ ability to produce silk facilitates wide ranges of behaviours, including prey capture, web construction, reproduction, locomotion and dispersal. The silk glands differ across various spider lineages in terms of morphology, number and their physical and chemical properties. Most species have several silk glands (from 2 to 8 distinct kinds), yet our understanding of how the spiders use different silk glands during specific behaviours remains limited. To address this gap, our research addresses two key questions: 1) How does a single species utilize their complete multi-silk gland repertoire across various behaviours and 2) whether patterns of silk gland use are conserved or diverge across spider lineages performing the same behaviour. To investigate this, we combined high-speed videography, laboratory and field behavioural observations, snap-freezing of spiders mid-behaviour, diverse microscopy techniques and comparative phylogenetic analysis. Our results demonstrate that individual species often deploy multiple silk glands simultaneously during different behaviours, indicating a complex and heterogeneous use of silk system. Comparative analysis across lineages reveals that, despite certain behaviours evolving convergently multiple times across the spider phylogeny, silk gland usage remains remarkably consistent. Glands which are thought of being associated with specific behavioural contexts like locomotion, web building, and dispersal, are frequently deployed also in other contexts, and often in combination. These findings challenged the prevailing "one gland, one behaviour" view of silk biology, suggesting that multi-gland deployment is a widespread strategy in various behaviours in spider silk biology. This study provides a new perspective on the relationship between silk gland evolution and behavioural diversification in spiders.

Animals that construct extended phenotypes have to balance different mechanical requirements – structural integrity is typically achieved with stiff and strong materials, whereas structures used in dynamic situations have to be elastic and tough. Netcasters (Deinopidae) have evolved a unique predatory behaviour, where the silken net is held with the front legs and propelled against the prey. During the strike the spiders, hanging in a silken scaffold, launch themselves forward and rapidly extend the net before casting it over the prey. Subsequently, the net collapses around the prey and the spider swings back into its original position. During this dynamic movement the strains and elastic responses of the netcaster web radii and frame exceed by far those observed in orb web radii subject to prey interception as well as such strains spider lines can typically sustain, which prompted us to investigate the properties, structure and spinning of these threads. We found that netcaster radii have a unique structure, highly distinct from orb web radii, with an elastomeric core surrounded by looped bundles of thin fibres. This architecture results in an unusual mechanical profile: the threads are initially compliant and highly extensible, enabling effortless stretching at high speed, but they stiffen at higher strains as the fibre loops straighten, preventing the thread to break under the load of the prey. Notably, spiders control this compound architecture through a reel-spinning technique, controlling loop formation and fibre mixture to establish an elasticity gradient across the web—stiff and strong in the main frame lines, yet soft and hyper-elastic in the lower radii that undergo the greatest deformation during prey capture. These findings represent a unique case of behavioural modulation of silk processing to circumvent biomaterial trade-offs, enabling extraordinary dynamics and specialization of web architecture.

Predatory risk may alter growth, behaviour, hypothalamic–pituitary–adrenal (HPA) axis responses, metabolism and ultimately fitness. We examined how chronic exposure to simulated predation affects behavioural, endocrine and physiological responses in growing mallard ducks (Anas platyrhynchos). From hatch to six weeks, ducklings were reared in either a poor-quality environment with repeated simulated predator exposure (hawk silhouette) or a good-quality environment with minimal disturbance. We quantified growth, HPA axis function using standardized corticosterone (CORT) measures, and metabolism using fecal metabolomics. Duckling growth and structural size did not differ between environments, indicating compensation for energetic costs when food was unrestricted. However, endocrine and metabolic responses revealed environment- and age-dependent effects. At week one, ducklings exposed to predation risk showed distinct metabolomic profiles indicating increased energetic demand, including upregulation of amino acid, carbohydrate, antioxidant, and lipid metabolism pathways. These metabolic shifts coincided with altered baseline CORT, consistent with transient HPA axis modulation. By week three, metabolomic profiles and baseline CORT were similar between treatments, indicating physiological habituation despite unchanged behavioural responses to predator stimuli. Our results demonstrate that early-life predation risk can induce transient shifts in endocrine and metabolic phenotypes without measurable effects on growth in ducklings. However, these responses may be contingent on favourable environmental conditions and unrestricted food availability which likely mitigated energetic trade-offs associated with chronic predation risk.These findings highlight metabolic plasticity as a potential mechanism by which developing animals may respond to chronic threats, emphasizing the importance of integrating physiology and metabolomics into behavioral ecology.

Some prey species have evolved background matching, that is they resemble their surrounding environment in terms of colour and/or brightness. When inhabiting patchy environments, they may even have evolved specialised phenotypes: each phenotype matching a specific subset of patches. To benefit from the match between their phenotype and this subset of patches, individuals should preferentially select patches within that subset, a process known as matching habitat choice. Matching habitat choice is beneficial to colour polymorphic prey populations, as it reduces individuals and population-level predation risk. We tested for matching habitat choice in green-brown polymorphic grasshoppers using experimental arenas lined with green-brown checkerboards. Because previous work suggested that grasshoppers may distinguish green and brown only achromatically, individuals were tested on green-brown checkerboards that were either achromatically-mismatched (different luminances and hues) or achromatically-matched (same luminance, different hues). Grasshoppers selected coloured microhabitats independently of their colour morph. They preferred green patches on achromatically-mismatched checkerboards and tended to prefer brown patches on the achromatically-matched checkerboards. We conclude that green-brown polymorphic grasshoppers do not engage in matching habitat choice for hue, even though they likely distinguish green and brown chromatically. We finally investigated the potential of the preferred patches to provide increased concealment from their predators. Both morphs were better concealed achromatically against the preferred patches. Green-brown polymorphic grasshoppers may thus perform matching habitat choice, though through brightness matching only. Such brightness-based habitat choice could reduce predation risk at long distance and under low-light conditions, stressing the importance of considering both hue and brightness in studies of habitat choice for colour purposes.

Strong electric fields have been used for over 30 years to deter sharks from biting humans and, increasingly, are being trialled as a means to prevent depredation of target fish species and reduce bycatch of sharks in commercial fisheries. It is assumed that strong electric fields deter sharks by overwhelming their highly sensitive electrosensory system, which is normally used by sharks to detect the minute electric signals emitted by prey and conspecifics. However, when being repulsed by electronic deterrent devices, sharks often display marked twitching of the eyes, jaws, head and body, which suggests that the emitted pulses cause muscle contractions that may also contribute to the deterrent effect. Moreover, despite considerable variation in the type of electrical pulse emitted by different commercially available shark deterrent devices, there is little empirical research on the effect of varying the pulse waveform on its effectiveness in deterring sharks. These observations indicate there may be scope to improve the effectiveness of electrical shark deterrents through optimisation of the pulse waveform for stimulating the electrosensory system and/or directly causing muscle contractions. Here, we studied the responses of free-swimming and anaesthetised sharks (including blind sharks Brachaelurus waddi, bonnethead sharks Sphyrna tiburo, whitetip reef sharks Triaenodon obesus), and for comparison a non-electroreceptive teleost fish (the yellowfin bream Acanthopagrus australis) to pulsed electric fields that differed in pulse shape, pulse duration, and pulse repetition rate. We found that pulse duration, not frequency, was the strongest driver of both deterrence and muscle twitching. These results provide the basis for improved electronic shark deterrent devices that may help to save the lives of humans and sharks.

Flowering plants which attract and benefit from visitation by a diverse suite of animals are often described as possessing a ‘generalised’ pollination system. There is considerable variation, however, in the actual contribution of different visitors to generalist plant reproduction. This has prompted efforts to quantify the pollination effectiveness of specific species or types and thus separate ‘true’ pollinators from mere visitors, typically by measuring the effectiveness per group in isolation. While valuable, such methods may neglect synergistic effects which arise from multi-species foraging at the same resource, and how the behaviour of pollinators can change when a flower becomes crowded.

To better understand how interactions between insects impact their behaviour at flowers, and thus the likelihood of successful pollination, I collected video data of insects foraging at the flowers of generalist native plants in Sydney. I focused on the Myrtaceae and Proteaceae families as these are ubiquitous in Australian landscapes and attract a large diversity of species to their flowers, including: bees, flies, beetles, and wasps, as well as nectarivorous vertebrates. I calculated whether the time an insect spends at a flower is influenced by the diversity of other foragers present, using bees as the focal taxa. Shorter visit times per flower suggest that bees are moving more frequently to other flowers to forage for their required pollen or nectar, and are therefore more likely to transfer pollen between flowers. Thus, reduced visit time with an increased number of co-foraging visitor types present (i.e. a more crowded flower) is consistent with visitor diversity benefiting plant reproduction, even if some of those visitors are themselves not very effective pollinators. Such data on insect behaviour at flowers adds to our understanding of the material benefit of high biodiversity in pollinator communities and the mechanisms underlying the success of generalist plants.

Sleep is a widespread and ancient behaviour, yet its function and evolutionary origins remain enigmatic. Laboratory studies dominate our understanding of sleep, leaving critical questions about sleep expression in natural environments – particularly for invertebrates, where wild sleep remains unexplored. After establishing robust evidence for sleep and REM-like behaviour in the jumping spider Portia fimbriata in the lab, we here investigate how these behaviours manifest under natural conditions. We collected all-night infrared recordings of sleep in a) free-living individuals (n = 10, > 120 hrs) in their natural rainforest environment and compared their patterns (total sleep duration, REM-like sleep duration, REM-like bout amount) to two laboratory baselines: b) raised in the lab (n = 10, > 120 hrs), c) brought to the lab from the field (n = 10, > 120 hrs). Because the field environment introduces frequent abiotic and biotic disturbances this system allows us to test if sleep architecture is altered under natural conditions. Despite more frequent disturbances in the field, sleep and REM-like states were consistently expressed, indicating robust intrinsic sleep architecture. To further understand the ecological context of sleep, we surveyed sleep sites of P. fimbriata in the field (n = 61). Initial analyses reveal sex-specific sleep site strategies: females more frequently slept in Portia webs, which were generally less exposed than heterospecific webs, while males more often used webs of other spiders. Sleep sites used by females also tended to contain more debris, and exposure increased with height. Together, these patterns suggest that sex-specific sleep site choice may help buffer environmental disturbance and predation risk. To our knowledge, this study is the first to investigate sleep and REM-like behaviour directly in a free-living invertebrate, offering crucial insight into the ecological and evolutionary significance of sleep.

Senescent declines throughout life are thought to be inescapable, in both wild and captive conditions. The reduced survival probabilities and reproductive output of senescent individuals may affect population dynamics. Inherent difficulties in following individuals over sufficient periods, however, means senescence has generally been studied in short-lived wild species, or in captivity, and the presence and magnitude of actuarial and reproductive senescence in the wild remains unknown for many long-lived species. Sea turtles are an excellent system in which to investigate senescence in long-lived species. Despite the testudines being generally known for their negligible rates of senescence, recent work on captive green sea turtles (Chelonia mydas) has shown evidence of actuarial, but not reproductive, senescence, in contrast with other species in this order. Using a unique 34-year data set of capture-mark-recapture and reproductive records of over 700 individual female green sea turtles nesting in Northern Cyprus, we present the first study of senescence in wild sea turtles. We find no evidence of actuarial senescence. However, when accounting for an individual’s breeding interval and previous reproductive output, the probability of reproducing declines with age, offering evidence of reproductive senescence, again contrary to findings in captive individuals, and other testudines. These differences between captive and wild individuals provide insight into the potential conditions under which senescence may occur. Few long-lived species have been studied comprehensively enough at the individual level, and for long enough to provide insights into how senescence may manifest. Fewer still have captive populations with which comparisons can be made. Quantifying the rates and drivers of senescence in these species contributes to an explanation of the evolutionary context of senescence, and how populations of long-lived species change as the individuals within them age.

Individual differences in behaviour are increasingly recognised as linked to variation in immune function and oxidative physiology. Behavioural traits such as boldness, exploration, and activity shape how animals interact with their environment, influencing parasite exposure and energetic demands. At the same time, immune responses are costly and generate reactive oxygen species, which are essential for innate immunity but, if not buffered by antioxidants, can damage cells and alter behaviour by affecting energy balance. Despite this evidence, the interactions among behaviour, immunity, and oxidative physiology remain poorly understood in wild animals. The pace-of-life syndrome predicts that proactive individuals invest less in immune defences and may be more vulnerable to oxidative costs, potentially increasing parasite susceptibility, although contrasting results have been reported. Here, we investigated these relationships in the wild rodent Mastomys natalensis in Tanzania, a widespread pest species responsible for zoonoses such as Lassa fever and plague. Ninety-six individuals were trapped in the field, tested for personality, and divided into two groups: a treatment group injected with lipopolysaccharide (LPS) and a control group injected with phosphate-buffered saline (PBS). In both groups, we quantified inflammatory responses, oxidative damage, and antioxidant capacity before and after the challenge. This is the first integrated experimental test of behaviour, immunity, and oxidative stress in a wild rodent species. Our findings provide novel insights into behavioural ecology, revealing how personality and eco-physiological state interact, while also informing understanding disease dynamics and management in a zoonotic species.

Multimodal communication enables social insects to coordinate complex collective behaviours. Individuals’ responses to multimodal signals depend on the perception of each stimulus component and on their neural integration, often resulting in behavioural outcomes that differ from those elicited by isolated cues. Despite its relevance, the integration of multimodal stimuli in social insects remains poorly understood, particularly in communicative contexts. In several ant species, alarm signalling is multimodal, combining pheromone release and stridulation. Here, we focused on the alarm behaviour of the ant Myrmica scabrinodis, studying the detection of chemical and vibroacoustic components of its multimodal alarm signals. We assessed the sensory roles of antennae and legs through electrophysiological recordings. Chemical cues were primarily perceived by the antennae, which responded robustly to alarm pheromones but showed no sensitivity to vibroacoustic stimuli. Conversely, vibroacoustic signals were detected through the legs, with marked inter-individual variation and a predominant sensitivity associated with the left hind leg, which appeared sufficient for stridulation detection. These results indicate that chemical and vibroacoustic cues are processed independently at the peripheral level, implying that their integration occurs centrally. We also found clear evidence of sensory lateralisation: the right antenna was more sensitive to pheromones than the left, consistent with population-level lateralisation patterns reported in other social insects. Such asymmetries may facilitate efficient collective responses by promoting shared, coherent behavioural responses within the colony. Overall, our findings highlight sensory specialisation and lateralisation in ant alarm communication, providing insights for future studies into how ecological constraints and social structure shape the evolution of multimodal communication and collective behaviour in social insects.

Effective responses to predators are critical for survival, especially when anti-predator behavior varies by context and requires adaptive flexibility. In ravens, most studies focus on adult mobbing behavior, which is influenced by learning, social context, and early-life experiences. However, surprisingly little research has considered the development of these anti-predator responses, particularly for non-mobbing behaviors. To fill this gap, we first investigated the ontogeny of anti-predator behaviour in captive raven families by exposing 12 family groups to a potentially dangerous human at two of their offsprings' developmental stages: shortly after their fledging and then when nearing independence. Second, we tested only the offsprings in isolation, to assess learning, individual differences and their consistency across contexts. In the first experiment, we found that parents reduced their antipredator behavior as offspring neared independence, while the offspring ignored the dangerous heterospecific less as they grew older. In the second experiment, we found an increase in behavioral variance between individuals as they aged, and preliminary evidence of individual differences in antipredator behavior. These findings provide insights into the development of anti-predator behavior in ravens and explore the role of social cues and individual differences in shaping effective responses to threats.

To establish themselves in novel environments, invasive species must rapidly adjust to local conditions. Some species are more successful than others at colonizing new areas and expanding their novel geographic range. Understanding the behavioral traits that facilitate variable range expansion can provide insight into invasion dynamics and success. One potential contributor is the behavioral response to immediate danger, which may enhance foraging efficiency and survival. We compared a proxy of predator-avoidance behavior using the flight initiation distance (FID) assay, between two closely related avian invasive species in Israel: the rapidly expanding Common Myna (Acridotheres tristis) and the slower-spreading Vinous-breasted Myna (A. leucocephalus). The Common Myna exhibited greater tolerance to human disturbance and perceived predation risk, reflected in shorter FIDs and a pattern to escape by running, than the Vinous-breasted Myna in areas of their range overlap. Additionally, Common Mynas also showed shorter FIDs than the native House Sparrow (Passer domesticus), particularly in more recently colonized regions and in areas with higher human densities. These results indicate that the Common Myna displays a flexible antipredator strategy that allows efficient foraging even under high levels of human disturbance. Such behavioral flexibility may facilitate greater invasion success and range expansion in the Common Myna, whereas limited flexibility may constrain its congener. These findings also have implications for developing control measures targeting invasive myna populations.

Despite the diversity of behavioural and morphological traits in microlepidoptera, defensive hypotheses for such traits are rarely proposed. Here, we tested whether a distinctive resting posture observed in the family Gracillariidae helps moths avoid predation, using Caloptilia sapporella as a model system. This posture—where paired fore- and mid-legs elevate the head steeply—creates an atypical appearance that may resemble plant debris, especially in combination with slender, dull-coloured wings. Using the jumping spider Telamonia vlijmi as a predator, we first compared survival rates between C. sapporella and three similarly sized moth species that adopt a common resting posture. Next, we compared survival between wild-type and posture-disrupted C. sapporella to isolate the protective effect of the posture. Finally, using naïve predators, we tested whether predators’ prior experience with debris affected prey survival, as predicted by masquerade theory. We found that C. sapporella experienced markedly fewer attacks than heterospecific controls. In the second experiment, posture-disrupted individuals were attacked more often than intact conspecifics, indicating that the head-elevating posture is a key component for avoiding attacks. However, in the final experiment, attack rates did not differ between debris-experienced and debris-naïve predators, providing no support for misidentification of C. sapporella as plant debris. Our results suggest that the atypical resting posture confers protective benefits that do not appear to depend on predators’ prior experience with plant debris, highlighting microlepidoptera as an underexplored system for predator–prey research.

Spiders (Araneae) are one of the most diverse and ecologically important groups of arthropods, inhabiting a wide range of habitats worldwide. As predators with varied prey ranges and complex foraging behaviours, they play a vital role in regulating invertebrate populations, making their foraging behaviour a key focus in behavioural ecology. This review synthesises findings from laboratory- and field-based prey choice experiments examining how internal and external factors influence spiders’ foraging decisions. Internal factors include life stage, physiological state (e.g., hunger), and reproductive condition, while external factors involve environmental pressures such as predation risk, prey availability, and habitat complexity. These variables are often experimentally manipulated to isolate specific behavioural drivers. Different species respond differently to these factors, navigating associated trade-offs in context-dependent and species-specific ways. Evidence suggests that prey choice in spiders involves flexible, adaptive decision-making rather than fixed, innate preferences. Learning and experience also substantially shape foraging behaviour, highlighting cognitive contributions that enhance spiders’ ability to adjust to changing conditions. By integrating empirical results from controlled experiments, this review provides a comprehensive understanding of spiders’ prey choice, emphasising behavioural flexibility and the significant role of learning in shaping their foraging strategies.

Predation drives the evolution of prey traits that reduce the likelihood of detection or capture. While antipredator morphology is well-documented, patterns of behavioral and cognitive trait variation along gradients of predation pressure remain underexplored. Furthermore, it is unknown whether key social or sexual differences between ecologically similar species can result in distinct responses to predation pressure. Here, we compare species that differ in sexually selected traits: the syntopic poeciliid fish species Gambusia affinis (no sexual dichromatism) and Poecilia latipinna (high sexual dichromatism) across paired high- and low-predation sites in three major central Texas watersheds. We assessed behavior (exploration, shyness, and social motivation) and cognition (cognitive flexibility) in both species. We expected that behavioral and cognitive responses to predation risk would be magnified in the larger, more conspicuous P. latipinna. We also predicted that predation regime would show parallel effects on traits across waterways. Surprisingly, we found a stronger overall effect of predation regime on trait variation in G. affinis than P. latipinna. While we found no consistent differences in the other three traits, we did find that predation regime led to consistent patterns of social motivation variation within species, but opposing patterns between species. Larger P. latipinna were less socially motivated than smaller P. latipinna, only in higher-predation environments, while larger G. affinis were less socially motivated than smaller G. affinis only in lower-predation environments. This finding suggests that the relative costs and benefits of social behavior may differ even between ecologically similar species experiencing the same predation pressure. Taken together, our study highlights that effects of predation regime are not monolithic, and that ecological factors other than predation may exert large influences on behavioral trait variation.

Butterflies often use their colours to signal unprofitability to predators and more conspicuous colour signals increase predator and avoidance learning. These signals can be either on the dorsal or ventral surface of butterflies, which are differentially shown during rest or flight. Here, we use detectability as a proxy for conspicuousness, and test whether toxic butterflies are more detectable on both the dorsal or ventral side using a computer game where humans hunt butterflies against multiple backgrounds. We analysed whether detectability is related to toxicity, which was assessed using Daphnia mortality assays. We tested (1) if the detectability of dorsal or ventral butterfly wings were related to toxicity, and (2) if butterflies that were more toxic had similar dorsal and ventral detectability. Overall, phylogeny strongly influenced the likelihood of toxicity. We found that detection time of dorsal wing surfaces was positively related to toxicity whereas the detection time of ventral surfaces was not. Conversely, toxicity was positively related to the similarity of detection time between both wing surfaces. Our results suggest that toxic butterflies are similarly detectable on either wing surface, but the dorsal side tends to be more easily detectable. These findings are consistent with the prediction that aposematic signals are particularly relevant when animals are in motion, as in butterflies the dorsal side is visible during flight.

Predation risk induces an array of physiological and behavioral responses in prey that facilitate survival chances. These anti-predator responses can have consequences for foraging behaviour. According to extensive empirical evidence, prey under risky conditions experience a food-safety trade-off, in which the prioritization of risk avoidance results in lower resource acquisition. However, predation risk also induces physiological stress responses, which increase nutritional demands needed to fuel antipredator responses. Thus, prey are expected to optimize their macronutrient intakes towards higher carbohydrate diets while also seeking safety under predation risk. To determine how predation risk influences foraging behaviour and macronutrient intakes, we measured the foraging choices of Psammophilus dorsalis in large semi-outdoor enclosures, where the composition of [high C:P (carbohydrate:protein) vs. low C:P] and access to (near vs far from refuge) food options (mealworms) were manipulated. We contrasted the behaviour and stress physiology of lizards under predation risk and control conditions. Lizards exposed to predation risk exhibited high corticosterone levels, reduced activity, and preferred to forage from safer sites near their refuge in all foraging treatments, compared to control groups that did not experience predation risk. In contrast, when high C:P mealworms were provided only far from refuge compared to near the refuge, lizards under the risk of predation increased their foraging effort to obtain the higher C:P food. Our study provides novel evidence supporting both the food-safety trade-off and nutritional optimization in governing foraging decisions of a vertebrate species when faced with predation risk.

Predation is a major selective force shaping prey behavior. While numerous studies have examined prey responses to varying levels of predation risk to balance survival with other life tasks, it remains unclear whether similar responses occur in victims of cannibalism—where predator and prey are conspecifics. Within cannibalistic populations, potential prey may adjust their behavior to balance foraging effort and anti‑predator vigilance in response to varying risks of cannibalism. Furthermore, due to the common size differences between cannibals and prey (i.e., larger individuals are more likely to be a cannibals against smaller prey), an ontogenetic shift in prey behavior in response to cannibalism risk is hypothesized as individuals grow from small potential victims to larger potential cannibals. In this longitudinal laboratory study, we used the highly cannibalistic bold jumping spider, Phidippus audax, to test: 1) whether lifelong exposure to different levels of cannibalism risk (None vs. High) alters vigilance , foraging effort , and visual response to conspecific cannibals ; and 2) whether these behavioral patterns shift as individuals mature from juvenile to adult. Our study design additionally allows us to explore the effects of size asymmetry on cannibal and victim behavior and to examine sex differences in behavior in response to cannibalistic risk. This latter opportunity – i.e. to explore sex differences in the ontogeny of risk-related behavior – is possible due to our longitudinal design, as immature spiders cannot be sexed. We will discuss preliminary results of all aspects of this experiment.

Climate change can alter predator–prey dynamics by modifying the movements and distribution of migratory prey. Yet, predator responses to these changes remain poorly understood, particularly in behaviourally flexible central-place foragers. In Serengeti National Park, Tanzania, increasing evidence shows that increased rainfall over recent decades has altered the movement patterns of large migratory herbivore herds, the main prey of spotted hyaenas (Crocuta crocuta). Consequently, the annual presence of migratory prey within hyaena clan territories declined from about 12% of the year in 1990–1994 to 7% in 2015–2019. Using long-term data from three central Serengeti hyaena clans monitored between 1990 and 2019, we investigated how this decline affected hyaena feeding activity, approximated using the monthly number of observations of feeding events, and clan size. Migratory prey presence strongly predicted the number of feeding events recorded, which decreased as prey presence declined over time. Despite this reduction in observed feeding events, two of the three clans increased in size over time. This suggests that reduced access to migratory prey did not negatively affect hyaena populations, highlighting the behavioural flexibility of hyaenas and their ability to cope with climate-driven changes in prey availability. As an exploratory study, our results generate new, testable hypotheses for future work aimed at identifying the mechanisms by which hyaenas compensate for reduced prey availability under changing environmental conditions.

The milkweed bugs (Lygaeinae) are adapted to feeding on toxic hostplants from which they sequester cardenolides for antipredator defence. Most have red-and-black warning coloration, and when species co-occur, they can benefit from mimicry. Many species also feed on non-toxic plants, leading to variation in sequestered defences. Since they also synthesize defensive secretions autogenously, species may differ in how their defence depends on sequestration. When several species use the same hostplant, they may differ in the amount of sequestered cardenolides, indicating different effectiveness of sequestration. This may have implications for antipredator defence and mimetic relationships among co-occurring species. We tested responses of naive hand-reared great tits (Parus major) to warning coloration and antipredator defence of two milkweed bug species – Lygaeus creticus and Spilostethus pandurus – that share oleander (Nerium oleander) as a source of cardenolides but differ in the quantity of sequestered chemicals. We compared learning rates between the birds trained to avoid different species and their generalisation between the species. To test for the importance of sequestration, we compared two different treatment groups of each milkweed bug species, one raised on oleander and the other on control sunflower.

While L. creticus was equally well defended irrespective of hostplant, the defence of S. pandurus was hostplant dependent, and the bugs raised on control sunflower suffered high mortality. While both species benefited from predator generalisation when raised on oleander, the predator experience with sunflower-raised S. pandurus decreased the survival of L. equestris. The results support the hypothesis that milkweed bugs differ in how dependent they are on sequestration for antipredator defence, and indicate a trade-off between defence sequestration and synthesis. The nature of mimetic relationships between species may also depend on available hostplants.

Animals which possess secondary defences that render them unprofitable for predators are frequently conspicuously coloured, facilitating predator learning of the association between their colours and unprofitability. According to theory, this association, referred to as aposematism, enables the predators to avoid such animals as prey in subsequent encounters through the stimulation of the predator’s visual and chemical sensory channels. Apart from studies showing their role in sexual selection, warning coloration and secondary defences are seldom studied beyond their role against predators. This is surprising given the multiple additional benefits that well-defended animals can obtain. Using mainly aposematic amphibians and insects –the best-studied aposematic taxa– as examples, we show that research on aspects of aposematism beyond colouration and secondary defences represent only about 5% of the literature published since 1975. We then compile and present evidence on the correlates of aposematism, as well as the broader benefits it provides by: (1) discussing how aposematism can shape behaviour (e.g., mate attraction, foraging, gregariousness, exploration, aggression, parental care), ecology (e.g., diel activity, microhabitat use, life history traits), and physiology (e.g., visual spectral sensitivity, thermoregulation, metabolic rates), and influence diversification and extinction patterns; (2) underlining the importance of accounting for both the visual and chemical components of warning displays; and (3) highlighting the ways in which the aposematic phenotype may serve as an “umbrella trait” for the evolution of complex and diverse behaviours in defended species. Finally, we assess the possible threats for aposematic species in the face of global change and outline a few promising avenues for research to further clarify the wide-ranging benefits of aposematism across taxa.

In species with elaborate, multimodal courtship displays, component signals typically explain only a fraction of mating and reproductive success. Several hypotheses have been advanced for the coexistence of multiple signals in the courtship of most species, however few studies have investigated empirically how configurational properties that are related to the dynamic presentation of component signals are associated with the attractiveness of courtship displays. Here we present the results of a few recent studies conducted in avian taxa that are known for the extreme elaboration of their courtship, that is manakins, bowerbirds, and birds of paradise. We show that female preference is influenced by aspects of courtship choreography, such as the temporal coordination and sequential order of component signals. We discuss the potential role of motor and social learning in the development and performance of these elaborate displays and suggest new approaches to study attractiveness based on fine analysis of receiver behavior.

The diversity of signaling traits within and across taxa is vast and striking, prompting us to consider how novelty evolves in the context of animal communication. New communication features could first arise in signalers or receivers, but the microevolutionary processes that result in novel signal or receiver traits remain relatively unknown. This is, in part, because observing the contemporary evolution of new traits is so very rare. Further, how new sexual signals arise, persist, and spread is difficult to envision because signals and receiver responses frequently coevolve, and new signal features should disrupt existing communication systems. New sounds, smells, colors, and dance moves should thus be rejected by nearly all receivers. How then do novel sexual signals come to be? We have discovered multiple novel mating songs in introduced Hawaiian populations of the Pacific field cricket (Teleogryllus oceanicus) that appear to have evolved in response to a prominent invasive natural enemy (an acoustically eavesdropping parasitoid fly). In 2019 we initiated a longitudinal study to track the evolution of these novel songs (e.g., purring, rattling) alongside the preferences of intended and unintended receivers (female crickets and parasitoid flies, respectively). We ask: How do signal receivers facilitate and respond to novel signal evolution? On biannual trips to six Hawaiian populations, we used standardized phonotaxis trials to generate preference functions describing the shape of individual and population-level cricket and fly preferences. Over six years of tracking, we found that female cricket and parasitoid fly preference functions vary among individuals, across populations, and over time. But preferences do not appear to be “tracking” novel signals. Rather, signal evolution was facilitated by relaxed preferences that accommodate a wide variety of song types. Continued tracking could capture the earliest stages of coevolution between signalers and receivers.

Understanding the prevalence of extra-pair mating and its implications for reproductive success can help us better explain sexual selection. Extra-pair reproduction (EPR), where mating occurs with a male outside the social pair, is common in most bird species. Male extra-pair behaviour – polygyny ¬– is advantageous and drives sexual selection; these males produce additional offspring, leading to greater lifetime fitness. Although females partake in EPR, evidence for equivocal fitness benefits are scarce. Previous work has focused on the benefits the female receives from the extra-pair partner, either directly (e.g., resources) or indirectly (e.g., good genes). However, results are inconclusive, and it is still unclear what female birds gain from EPR. We used a twenty-year genetic pedigree from a closed wild population to test the potential fitness benefits of EPR to females by comparing the lifetime fitness of monogamous and polyandrous female house sparrows Passer domesticus in the wild, using two key metrics of lifetime fitness: (i) the number of offspring and (ii) the number of recruits (offspring that survive to reproduce). Our results suggest that, after controlling for lifespan, polyandrous females have more offspring than monogamous females, yet do not have more recruits. Therefore, while polyandrous females produce more offspring over their lifetime, the number that survive to recruit is similar to that of monogamous females.

Non-random mating based on similarity at the major histocompatibility complex (MHC) is widespread. However, considerable variation in the strength and even direction of such preferences occurs across contexts, species, and populations. Previous behavioural trials on song sparrows (Melospiza melodia melodia) found disassortative odour preferences at class II MHC in individuals captured from southwestern Ontario. By contrast, song sparrows breeding in southeastern Ontario (about 400 km away, and belonging to the same subspecies) showed MHC-assortative social mate choice under field conditions. This difference could reflect (1) differences in context and approach (controlled preference trials in captivity versus expressed mate choice in the wild) and/or (2) population differences in genetic diversity at MHC relative to optimal diversity. To address the second possibility, we compared the two populations (n = 36 southwest and 60 southeast) at individual and population-level genetic diversity at class II MHC. Individual genetic diversity at MHC (allelic richness) was 21% higher, and mean pairwise distance (UniFrac) at MHC was 4.4% higher, in the southeast population (mating assortatively in the field) than in the southwest population (showing disassortative odour preferences). Our findings are consistent with a compatible-genes model of mate choice where the optimal MHC diversity is intermediate (i.e. the golden mean model). Our findings suggest that MHC-based mating preferences are flexible and capable of evolving in response to how current population genetic diversity at MHC compares to the optimal value.

Insects may experience trade-offs between flight capacity and reproduction. Such trade-offs may be pronounced in dung beetles, which depend on flight to locate ephemeral resources for breeding and are under intense sexual selection, yet this link remains experimentally untested. We investigate potential trade-offs between reproductive capacity and flight performance in the dung beetle, Onthophagus xiquenus. We predicted that both sexes would exhibit negative correlations between flight capacity and the size and number of gonads. To test this, we tethered 176 individuals to a flight mill to measure flight performance under controlled conditions. Following flight assays, we dissected the beetles, measured wing morphology, testis mass in males, and oocyte count in females. We found that longer flight duration and greater distance flown were associated with greater loss of body mass, indicating that intense flight activity in both sexes leads to the consumption of reserve tissues and water loss due to hydric stress. However, contrary to our predictions, we found no significant trade-off or reproductive cost between flight capacity and testis mass in males. In females, by contrast, we observed positive correlations between oocyte number and both average and maximum flight speed, irrespective of reproductive stage. Furthermore, females with intermediate oocyte counts exhibited greater body mass loss as a function of distance flown. Given that oocytes can be reabsorbed as an energy reserve, we hypothesize that reproductive investment correlated with flight intensity entails energetic costs in females, whereas such trade-offs appear less prevalent in males. This is supported by wing morphology: females with larger bodies (a proxy for reproductive capacity) develop thinner wings, while males maintain stable wing shape. Our results provide experimental evidence that flight performance trades off with reproductive traits in a sex-specific manner.

Conspicuous sexually selected traits typically evolve due to either strong intrasexual competition or mate choice. Possessing both extreme weapons and complex, multimodal courtship is rare. The Japanese rhinoceros beetle (Trypoxylus dichotomus; 'JRB') is surprising in this respect. Renowned for their large, condition-dependent ‘pitchfork’ horns, JRB males also perform ritualized courtship consisting of three distinct, alternating song types and abdominal trembling. The benefits of large weapons are well documented in this species, but the mechanism of sound production and the functional significance of courtship remain unexplored. Here, we characterize the multimodal courtship signals and putative sound production mechanism. Using behavioral assays, acoustic and vibrational analyses, and scanning electron microscopy, we demonstrate that JRB stridulatory organs are elytro-abdominal structures. Songs with distinct spectral and temporal characteristics are produced when males alternate between vertical, lateral, and figure-8 abdominal movements. Additionally, we manipulated the diet of adult males and found that courtship traits (e.g., song rate) are influenced by adult feeding regime: well-fed males sang faster than poorly-fed males, suggesting that song attributes may reflect biologically relevant information like male body condition. We also incorporated female traits (e.g., body condition, fecundity) in our analyses of mating responses. Our work expands our understanding of this otherwise-textbook large-weaponed, resource defense mating system by incorporating the impact of male songs and female physiology on the fitness of both sexes.

Conspicuous sexual signals that are meant to attract mates often attract predators. Yet, such conspicuous signals are widespread among animals, suggesting that animals may reduce signalling or compensate by showing heightened anti-predator behaviour to avoid predation. Such compensatory anti-predator behaviour, especially focusing on individual-level plasticity, has rarely been studied. Adult males of the tropical lizard Psammophilus dorsalis are an excellent model system to study this, as they dynamically switch their body colour from dull to conspicuous as part of their sexual signalling, which is associated with increased predation risk. We investigated whether P. dorsalis males modulate their anti-predator behaviour based on their signalling state in the wild. We tested the hypothesis that when displaying conspicuous sexual signals, males should increase their anti-predator behaviour to compensate for the increased predation risk. We simulated threat on males when they were in different signalling colours to measure their anti-predator response as Flight Initiation Distance and Emergence Time from a refuge. Before every assay, we photographed the focal male and a grey standard under the same light conditions to quantify conspicuousness. We tested whether males fled early and emerged later from their refuge when they were in conspicuous rather than in dull colour states. Our results suggest that males modulate their anti-predator behaviour based on their conspicuousness, showing within-individual plasticity. Males in conspicuous colours fled early, indicating that males do compensate for the increased predation risk. However, unexpectedly, they emerged early from their refuge when conspicuous, suggesting that they balance avoiding predation while minimising their opportunity costs in the context of mating. Our study thus demonstrates how anti-predator behaviour is influenced by multiple simultaneous selection pressures, including predation and mate acquisition.

Natal dispersal is a key life-history stage linking individual behaviour to gene flow and long-term population viability. Yet, most comparative studies relied on morphological proxies and coarse recovery ringing data, while the detailed transience phase — when juveniles explore and sample potential settlement areas — remains largely unquantified. The mismatch between the rapid growth of juvenile tracking and the scarcity of explicit dispersal syntheses limits our ability to identify the eco-evolutionary drivers of dispersal movement patterns across species. Here we present a comparative analysis of movement characteristics during natal dispersal in birds, built on a global collaborative effort resulting in more than 98 tracking datasets from more than 60 species, spanning passerines to waterfowl and covering a broad range of functional traits and environments. For each individual, we derive standardized movement indicators of the transience phase over standardised temporal windows using latent-state models that remain robust to irregular sampling and short gaps. We then relate these movement parameters to intrinsic and extrinsic predictors in hierarchical phylogenetic models. Predictors include morphology (body mass, wing length and shape), life-history pace and parental care, habitat specialization, migration strategy, spatiotemporal environmental heterogeneity, and anthropogenic features. We show consistent covariation between the species’ movement metrics and their flight efficiency, migration strategy, habitat openness and life-history pace. By moving beyond proxies to realized juvenile trajectories, this work provides a mechanistic, cross-species view of natal dispersal with direct implications for dispersal theory, metapopulation dynamics and conservation in a changing world.

Predators exert tremendous selective pressure on prey, influencing the evolution of different types of defences and how they are deployed. The individual impacts of defences on prey survival and predator deterrence are well explored, but few studies have investigated its impacts on fundamental growth and developmental processes, especially carryover effects that transcend metamorphic boundaries. This study examines how predation risk and defence costs in early life stages can influence growth, colouration, and boldness in the blessed leaf beetle Paropsisterna beata (Coleoptera: Chrysomelidae). The larvae of this species possess defences such as toxic secretions and regurgitation, and their frequent usage could incur a cost in adulthood, or signal the development of other defences after metamorphosis. Fourth instar larvae were allocated to a predation simulation regime of zero, one, or three simulated predator attacks per day over five consecutive days. The pupa stage duration, adult size, adult elytral colouration, and adult boldness were compared across the three regimes. Based on preliminary results, higher expression of larval defences decreased adult size, but only in male beetles. This indicates that high predation risk and defence deployment in early life stages can incur a cost on physical growth, providing evidence of the trade-offs involved in the evolution of defensive portfolios in prey, as well as highlighting the long-lasting effects of predation on an organism’s development.

Plasticity can shape individual fitness and the ability of populations to respond to ecological changes. This is particularly important for behaviors such as space use, social behavior and feeding activity, which directly affect how individuals use, compete for and share resources. However, limited knowledge exists on the consistency of these behaviors in stream fish, where individual observations are challenging. In a field experiment, we made repeated individual observations of territory size, feeding activity and social behavior of juvenile Arctic charr (Salvelinus alpinus). The study fish were individually tagged, placed in 12 stream enclosures (8 fish/enclosure) with different predation risk (one vs. five shelters) where conditions were stable (either high or low risk throughout the experiment) or unstable in time (fish exposed repeatedly to both low and high risk). Although juvenile Arctic charr used similar size areas under both stable predation risk treatments, they spent more time feeding and were in closer proximity when shelters were limited. In the unstable treatments, Arctic charr were plastic and modified their behaviors rapidly to altered shelter availability. Finally, Arctic charr grew fastest where shelters were limited throughout the experiments, perhaps because of increased feeding activity. This study improves our ability to predict how behavioral plasticity mediates growth and survival of stream fish in response to natural and human induced changes.

Alternative male tactics, such as sneaking, have complex and varied determination. In particular, in some species males may commonly switch tactics as they age and grow, while in others males commit to a tactic for life. This commitment is puzzling because alternative tactics often differ in optimal size, making a flexible life-history of sneaking when young, then becoming a dominant male when older, an obvious strategy. Here we present modeling results exploring the potential roles of learning and tactic subspecialization in selecting for fixed tactics. We show that learning within a tactic, or the innovation of different subtypes within a tactic, can favor fixed tactics by alleviating the loss of fitness of aging sneakers, and also by rewarding males that play a dominant tactic from maturity. We show how these modeling results produce new testable predictions for how plasticity in alternative mating tactics is expected to play out in nature.

Behavioral plasticity during early development plays a central role in how organisms respond to environmental change, yet it is often shaped by underlying morphology and physiology. Frogs provide a powerful system for examining these links as the aquatic larval stage represents a critical developmental window during which environmental conditions can shape traits that influence larval and adult fitness. To understand how a changing thermal environment may affect anuran population fitness, it is essential to identify how early-life temperatures alter larval behavior and traits that mediate these responses. Yet, we lack a clear understanding of how temperature modifies anuran larval behavior and whether these behavioral responses depend on their evolutionary history with temperature variation. We compared temperature-induced behavioral and morphological plasticity in the larvae of two spadefoot toad (family Scaphiopodidae) species: desert-adapted Spea bombifrons and mesic-adapted Scaphiopus holbrookii. We found that ecologically relevant temperature variation alters larval morphology, which in turn shaped larval behavior, with these differences conserved across two species adapted to different thermal regimes. Our results indicate that increasing temperatures will modify larval behaviors through temperature-induced morphological variation, and these modifications are associated with advanced developmental stage, suggesting short-term fitness benefits by facilitating earlier metamorphosis and escape from drying ponds. Despite this adaptive temperature-induced plasticity, body condition declined under exposure to hot temperatures, suggesting that plasticity alone may be insufficient to buffer anuran populations from heat. Overall, our results highlight behavior as a key mediator between developmental temperature and fitness, while illustrating how morphological constraints may limit the ability of behavioral plasticity to buffer anuran populations from climate change.

Nest-building is widespread among birds, yet a major architectural component of nests—the walls—are highly variable, and the evolutionary advantage of constructing walls remains unresolved. By integrating macroevolutionary analyses with experimental tests, we investigated whether nest walls evolved to prevent eggs from rolling off when disturbed. We evaluated two competing hypotheses: (i) the heavy-bird hypothesis, where heavier adults produce stronger vibrations that increase the risk of egg displacement, and (ii) the light-egg hypothesis, where lighter eggs are more prone to rolling due to reduced friction. Using phylogenetic comparative analyses across 4,030 bird species, we found that species with smaller body mass and lower egg mass were significantly more likely to build nest walls, suggesting a greater vulnerability in lighter eggs. Behavioural observations and experiments using 3D-printed eggs further demonstrated that lighter eggs had a higher probability of falling from nests with no walls. Together, these macro- and microevolutionary lines of evidence strongly support the light-egg hypothesis: nest walls have evolved as functional structures that stabilize eggs and prevent rolling during environmental disturbances. This study highlights how linking broad phylogenetic patterns with mechanistic experiments can uncover the selective pressures shaping complex nest architectures.

Parental coordination is quantified by two metrics: (1) alternation, the level of turn-taking, and (2) synchrony, the temporal organisation of each parent's behaviour with the other. Coordination emerges because carers must respond to each other in order to partition the work effectively. In socially monogamous species, individuals are thought to judge their partner’s quality through honest signals and adjust their investment accordingly, thereby shaping pair coordination. We examined parental coordination in the Spotted Pardalote (Pardalotus punctatus), a socially monogamous passerine bird in which both sexes incubate and feed the chicks. We investigated whether pairs coordinate their activities at the nest more than would be expected by chance using a randomisation approach and tested for an effect of individual quality on pair coordination. Eighty seven nests were monitored and individual quality was quantified using scaled body mass index for 130 individuals. Analyses of 23 nests showed that partners coordinated incubation activities more than expected by chance, and synchronised provisioning visits more than expected by chance during chick rearing. During incubation, low coordination was associated with low female quality and high male quality, whereas high coordination was associated with high female quality and low male quality. During chick rearing, higher synchrony was associated with higher male quality. Thus, individual quality affects parental coordination, supporting the idea that partners respond to one another according to their own quality and that of their mate. This study provides rare insights into coordination during incubation in a passerine bird since Northern Hemisphere male passerines typically do not incubate. Additinally, we examined the interaction between individual quality and coordination in a socially monogamous bird thereby contributing to our understanding of how honest signals might allow partners to negotiate over parental care.

04 04. Social Behavior & Group living

Parental care plays a crucial role in enhancing offspring survival in birds. However, most empirical work still relies on short, stage-specific observations that provide only snapshots of parental behaviour. As a result, we lack an understanding of how parental behaviour unfolds and reorganizes across the full breeding cycle. Moreover, parental investment is typically quantified as additive effort (e.g. summed visit rates or total time any parent is present), which obscures an important dimension of care: whether parents attend the nest together or alone. Despite its likely functional significance, joint nest attendance is rarely quantified explicitly, and its role may vary across breeding stages as costs, benefits, and constraints change. Here, we use continuous, high-resolution nest-box monitoring of wild jackdaws to quantify the temporal structure of nest attendance across the complete breeding cycle, from nest construction through incubation and chick provisioning to fledging. Using nest attendance states (0, 1, or 2 birds present), we derive measures of overall attendance and joint attendance and describe how both their mean levels and among-pair variation change across the breeding stages. We assess the consistency of pair differences over time and link stage-specific attendance patterns to corresponding fitness-related outcomes. We show that joint and overall nest attendance differ markedly between pre- and post-hatching stages, with pronounced shifts in both mean behaviour and among-pair variation across the breeding cycle. Together, these findings highlight how parental care is temporally organised across the full breeding cycle, showing how stage-specific snapshots or additive measures alone can miss important dimensions of parental behaviour and its links to reproductive outcomes.

The world is warming faster than at any time in the last 2000 years, with both long-term increases in ambient temperature and short-term heatwaves increasing in severity and frequency. While effects of heat on populations are often considered in relation to critical thermal maximums for survival, sublethal effects can significantly impair reproduction. Heat can both directly (via damage to gametes) or indirectly (via changes to parental behavior) impact reproductive success, even after conditions return to “normal”. Importantly, while direct effects of heat on gametes are well studied, less well understood are changes in behavioral responses. Many organisms require obligate parental care to successfully produce offspring, but plasticity in this behavior under heat stress will be limited by metabolic needs such as heat dissipation. Given that parental care is mediated by neuropeptides such as arginine vasopressin (mammals)/vasotocin (birds, fish) (AVP/AVT), and AVP/AVT is crucial for maintaining homeostasis under temperature stress, conserved neuropeptides are a promising mechanism for testing how long heat effects on care may last, identifying potential agents of selection on care, and, more broadly, investigating how individuals balance metabolic needs with parenting. Here, we test the hypothesis that reductions in parental care under heat stress are the result of tradeoffs between performing care behavior and thermal homeostasis. We examine AVT abundance in the preoptic area (POA), a brain region critical for maintaining parental care, and the pituitary, a brain region critical for maintaining homeostasis, under both acute and chronic heat stress in threespine stickleback fish (Gasterosteus aculeatus). By integrating neural mechanisms with behavioral measurements in a natural system experiencing rapid environmental change, this work will explicitly test predictions about how experiential factors alter patterns of plasticity in parental care.

Parents often juggle competing demands, such as protecting themselves versus their offspring from predators. Invasive predators are increasingly prevalent across ecosystems, presenting challenges to parental decision-making. Parents might respond inappropriately to novel predators, leading to severe consequences for their fitness. However, little is known about the behavioral and neural mechanisms by which parents make decisions when encountering unfamiliar predators. Threespine stickleback (Gasterosteus aculeatus) are small teleost fish found throughout the northern hemisphere. In Alaska, stickleback encounter various predators, including native rainbow trout (Oncorhynchus mykiss) and invasive northern pike (Esox lucius). We tested the hypotheses that the introduction of invasive pike alters average parenting behavior, and responses to invasive and native predators show different neural activity in the amygdala. Across two lake types (pike/no pike), we assigned parenting males to one of two treatments (native predator: trout; invasive predator: pike). Baseline behavior was measured, followed by exposure to one of the two model stimuli. Brain tissue was processed for immunohistochemistry to assess neural activity. Overall, we found stable levels of baseline parenting, differing responses to predators in lakes without pike, and reduced predator responses in lakes with pike. Our results will elucidate behavioral and neural mechanisms governing parenting decisions amidst different types of predation risk, providing insights into species interactions in changing environments.

Early development in vertebrates is a period of heightened neural plasticity, making it particularly sensitive to environmental influences. Adverse experiences, such as poor nutrition, disease or social adversity, can have lasting effects on behaviour and cognition. Yet, the extent to which these outcomes are shaped by the interplay between early environmental conditions and their predisposition (i.e., genetic and parental effects) remains poorly understood. We investigated these mechanisms in domestic canaries (Serinus canaria), where mothers often show maternal aggression (MA) towards their nestlings. We hypothesised that early MA exposure would increase impulsivity, promote resource acquisition through reduced neophobia, and enhance aggression, potentially leading to higher dominance ranks at the juvenile stage. Furthermore, we expected that these effects would be amplified under socially challenging conditions (i.e., high social densities), and in individuals predisposed to aggression. To test this, we cross-fostered full clutches within and between MA and noMA mothers, creating four experimental groups to disentangle predisposition and environmental influences. Once independent, juveniles underwent a series of standardised behavioural tests. Our results showed trait-specific patterns: aggression-related behaviours and response inhibition were primarily influenced by the nestling predisposition, while food motivation was mainly affected by the early-life environment, and neophobia was explained by a predisposition–environment interaction. These findings support the idea that MA may itself be a heritable trait, perhaps mediated by shared predispositions for impulsivity or poor behavioural regulation.

Animals regulate body temperature using a wide range of behavioral and physiological strategies. While most vertebrates are classified as either endotherms or ectotherms, some species can reversibly switch between these modes. This strategy, known as heterothermy, involves coordinated reductions in body temperature and metabolic rate that allow animals to conserve energy under conditions of resource limitation or environmental variability.

Hummingbirds represent an extreme example of heterothermy. During the day, they maintain body temperatures approaching 41.7 degrees and sustain some of the highest mass-specific metabolic rates among vertebrates to support hovering flight. At night, many species enter torpor, during which body temperature can fall to 3 degrees and metabolic rate is reduced by more than 90 percent. Although the molecular regulation of daily torpor has been studied in mammals, avian torpor remains poorly explored despite exhibiting some of the most dramatic physiological transitions known in vertebrates.

Here, we present the first multi-tissue transcriptomic analysis of torpor in Anna’s hummingbirds Calypte anna, spanning distinct metabolic states including normothermy, transition, and torpor. Using differential gene expression analyses and weighted gene co-expression network approaches, we identify tissue-specific and metabolic state–dependent transcriptional responses in early torpor. Across tissues, torpor is associated with coordinated changes in circadian clock components, extensive reprogramming of metabolic pathways, widespread shifts in RNA processing and alternative splicing, and transcriptional signatures consistent with enhanced cellular protection at low body temperatures.

By investigating these states across diverse taxonomic groups, we can determine whether convergent pathways or actors exist across the tree of life.