Abstract Mating systems are shaped by ecological and social factors and affect sexual selection. Gerbillinae (gerbils and jirds), a largely nocturnal group of Old-World rodents, show a variety of mating systems and social organisations, from promiscuity and solitary-living to monogamy and group-living. However, our current data on mating systems are limited to a few species, as direct observations of mating behaviour in wild nocturnal rodents are rare. Such observations are essential for understanding reproductive strategies and their evolutionary implications. Here, we present the first documented observations of mating in the wild in Anderson’s gerbil ( Gerbillus andersoni ), a solitary and territorial species for which reproductive behaviour has not previously been described. We recorded two independent mating events under full-moon conditions, a period associated with elevated predation risk for nocturnal prey. One observation involved a multi-male copulation consistent with male-aggregation mating — a strategy previously reported in only one other gerbil species, while the second depicted a mating pair. Courtship included female chasing and female tail-touching, followed by repeated brief copulations, with rival males occasionally aggressively interrupting mounting attempts. From these recordings, we constructed an ethogram that characterises courtship and mating sequences in this species. These observations expand current knowledge of gerbil reproductive behaviour and provide rare field-based evidence of mating under high-risk environmental conditions. As detailed ethograms are valuable for comparative behavioural analyses, but detailed descriptions of mating behaviour in rodents are limited to laboratory strains, our findings provide valuable data for future studies of the evolution of mating systems in Gerbillinae and in rodents in general.
Abstract Exercise wheels are simple devices for recording animal movement, but they elicit surprisingly complex behaviours. In laboratory rodents, running wheels are key for studying voluntary exercise, circadian rhythms, motivation, energy balance, stress physiology and brain plasticity. Outside rodents, wheel-like devices have also been provided to rabbits, cats, squirrels, reptiles and invertebrates. This wide use prompts a key ethological question: what does wheel running mean? This review investigates wheel use as a behavioural phenomenon, not just as a method for measuring activity. Historically, running wheels seem to have developed from captive-animal husbandry and display practices, especially squirrel cages. They were later adopted as scientific instruments in early twentieth-century rat research. Since then, wheel running has been interpreted in overlapping ways: as locomotor exercise, reward-seeking behaviour, exploration, play-like activity, coping behaviour, environmental enrichment or abnormal repetitive behaviour. These interpretations are not mutually exclusive. Their relevance depends on species, individual phenotype, housing, motivation, wheel design and available behavioural alternatives. The review argues that wheel running should not be treated as a unitary behaviour. In some animals, wheel access may provide behavioural agency and support motivated activity. In others, high or rigid use may signal constraint, stress, or limited environmental complexity. For non-traditional wheel-using species, video confirmation is important. Wheel revolutions may reflect climbing, pushing, manipulation, or other non-locomotive interactions. Further work should report animal characteristics, housing conditions, wheel dimensions, access schedule, sensor methods, behavioural context and welfare outcomes. Interpreting wheel running through an ethological framework helps distinguish voluntary locomotion, enrichment, play, coping and stereotypy. This can improve the use of wheels in behavioural research and animal care.
Abstract Scavenger communities are strongly shaped by competition for spatially and temporally variable food resources. This study investigated intra- and inter-specific interactions of Hooded Vultures ( Necrosyrtes monachus ) and Marabou Storks ( Leptoptilos crumenifer ) in urban and peri-urban feeding sites in Uganda. Behavioural observations were conducted at abattoirs and dumpsites and interaction rates were compared between food types (fresh bones vs cow dung). Generalised linear models (GLMs) with negative binomial error structures were used to assess the effects of environmental variables and group composition on abundance and aggression, while logistic regression was applied to determine factors influencing the probability of winning aggressive encounters. Hooded Vulture abundance was primarily influenced by food availability variables, particularly mean number of animals slaughtered per day and organic refuse. Intra-specific aggression increased significantly with group size and was higher at bone feeding sites, with a strong density-dependent effect confirmed by a positive relationship between group size and interaction frequency. Inter-specific interactions were driven by both Hooded Vulture and Marabou abundance, with stronger effects associated with Marabous. Marabou Storks dominated encounters, winning 93.4% of interactions and showing significantly higher competitive success. Overall, our results demonstrate that food quality and group size strongly structure competitive interactions, highlighting the role of anthropogenic food sources in shaping scavenger behaviour and community dynamics.
Abstract Territoriality involves a fundamental trade-off between the costs of defense and the benefits of having exclusive access to resources. Although theoretical models suggest that temporarily abandoning a territory to seek higher-quality resources can be evolutionarily profitable, empirical evidence of such “risk-taking” behaviours in competitive breeding systems is scarce. We investigated how territorial excursions influences the reproductive fitness and aggressive behaviour of Yucatán pupfish ( Cyprinodon artifrons ) in three wild populations. Contrary to traditional pupfish ecology assumptions, our results demonstrate that reproductive success is primarily driven by risk-taking behaviour, defined by the frequency and distance of territorial excursions, rather than territory size. However, this fitness gain came at a significant “re-entry cost”: high-risk males experienced more frequent agonistic combat and exhibited higher levels of aggression when returning to their territories. These findings suggest that territoriality in pupfishes is a highly plastic trait where risky excursions serve as a strategy to maximise spawning opportunities, regardless of spatial constraints. We propose that this behavioural coupling represents a tactical extension of territoriality, where high aggression functionally allows competitive individuals to reclaim their sites after an absence. Ultimately, our study highlights how correlated behaviours and behavioural plasticity enable the coexistence of divergent reproductive trajectories and provides empirical support for economic defendability theory in highly competitive environments.
Abstract Mortuary behaviour is rarely documented in rodents, likely due to limited observational opportunities. Using camera-trap footage from Ramat Hanadiv Nature Park, Israel, we report repeated predation by golden jackals ( Canis aureus ) on Indian crested porcupines ( Hystrix indica ) and describe a previously unreported postmortem interaction involving a porcupine conspecific. A female golden jackal was recorded twice killing and carrying juvenile porcupines, providing the first evidence of porcupine predation by golden jackals. Eight minutes after one predation event, an adult porcupine was observed carrying a carcass of a juvenile conspecific away from the site of death. Although cannibalistic scavenging or osteophagy cannot be excluded, the observations more strongly support an interpretation of mortuary behaviour. These findings expand current knowledge of porcupine behaviour and predator–prey interactions.
Abstract Many species of group-living rodents use ultrasonic vocalisations (USVs, >20 kHz) during affiliative contacts with group members. This study analysed USVs of adult Brandt’s voles Lasiopodomys brandtii on surfaces of three natural colonies. Most USVs had a flat contour of fundamental frequency (f0). The maximum f0 was 33.91 kHz and the minimum f0 28.43 kHz on average. The average duration of USVs was 27 ms and did not exceed 76 ms. Values of USV duration, fundamental and peak frequencies did not differ between colonies. Of 366 analysed USVs, 142 (38.8%) were emitted during series of audible alarm calls of other individuals; acoustic variables did not differ between USVs produced in presence or absence of alarm calls. The USVs of wild-living Brandt’s voles were very similar in the acoustic structure with affiliative USVs, previously recorded in captivity at short-term isolation or weak disturbance in social groups. We discuss that captive environment does not affect the species-specific pattern of USVs in the Brandt’s vole.
Abstract We examined the published literature regarding maternal stress in rodents. Rodents have been considered valuable models for studying maternal stress because their neuroendocrine systems, maternal behaviours and developmental responses to stress share important similarities with those of humans, allowing researchers to investigate underlying mechanisms and transgenerational effects. However, research in this area may have been influenced by diverse deviations that could affect the scope of behavioural and physiological outcomes. In an attempt to identify and highlight some of these biases, we performed a systematic literature review focused on the effects of maternal stress on the behavioural and physiological responses of wild rodents’ offspring compared with laboratory ones. This review finds that there has been a notable growth in studies on gestational stress in rodents in recent decades. However, the number of works on wild species is significantly lower than those using laboratory rodent models. In addition, most of these studies in rodent models are carried out with artificial stress factors (e.g. electric shock, noise, cold exposure) and fewer studies applied stressors more related to natural, evolutionary and ecologically relevant conditions, such as exposure to predators or cues indicatives of their presence. Thus, the reduction or absence of genetic variability and lack of environmental challenges can result in model rodents tested in laboratory settings reacting to predatory stress in a more uniform manner than wild species. In consequence, expanding investigations in wild rodents may offer valuable opportunities to understand the ecological and evolutionary bases of maternal stress in mammals.
Abstract Automatic, rapid facial mimicry consists in the replication (within 1 s) of an observed facial expression and supports motor and emotional inter-individual alignment. Facial expression responses have also been reported as non-matching (incongruent: different-expression response to the one observed; counter-mimicry: distinct expression with opposite valence to the one observed), linked to the mirror neuron system flexibly and modulated by experience and socioecological context. In non-human primates, incongruent responses are understudied, and counter-mimicry has not yet been explored. We analysed 962 h of play and aggression video from four captive chimpanzee groups (Mona foundation, Spain; Vallée des Singes and Beauval zoos, France) collected over three years. Facial expressions analysed included play-face/full-play-face, silent bared-teeth, scream-face, and pout-face. Rapid responses were classified as congruent (mimicry) or non-matching, i.e. incongruent response or counter-mimicry. We used GLMMs to assess whether each type of response (by a potential responder) occurred more frequently when observing (vs. not observing) the interactant’s facial expression (potential trigger). We applied a Random Forest classifier to evaluate whether the responder’s facial expression could be predicted from the trigger’s expression. Chimpanzees exhibited both mimicry and non-matching facial responses. Mimicry (83%) was the most frequent during play. Non-matching responses — though less common — were present during aggression (incongruent response; 8%) and during borderline play (counter-mimicry; 9%), e.g. play teasing/aggressive play. In non-matching responses, the responder’s expression was weakly predicted by the trigger’s expression, suggesting high individual or contextual modulation. In conclusion, chimpanzees can respond to others’ facial expressions not only through motor matching, but also via non-matching patterns. The presence of rapid counter-mimicry in chimpanzees suggests that the evolutionary roots of non-matching responses predate the divergence between the human and Pan lineages.
Abstract Ultrasonic acoustic communication of European rabbits, Oryctolagus cuniculus, was not investigated, although domestic rabbits are widely used as farm and laboratory animals. We examined acoustic variables of ultrasonic vocalisations (USVs, above 20 kHz) of adult and infant domestic rabbits. We analysed a total of 337 USVs from domestic rabbits, 102 USVs from 66 adults and 235 USVs from infants aged between 1 and 11 days, originated from 47 litters. Adults produced USVs when approaching researchers or towards their adult conspecifics. Infants produced USVs in response to a 10-min isolation of a litter from the mother. The fundamental frequency of 80% of USVs ranged from 17 to 43 kHz and was on average 31.0 kHz in adults and 30.6 kHz in infants. The duration of 80% of USVs was short, varying from 11 to 53 ms and was on average 22 ms in adults and 31 ms in infants. The USVs did not differ in their acoustic variables or contour shapes between adults and infants. Nonlinear phenomena were rare and occurred only in infant USVs. We show that lagomorphs represent a new mammalian taxon for which USVs are documented and compare acoustic variables of USVs in European rabbits with those in rodents.
Abstract Same-sex sexual behaviour has been reported across diverse animal taxa and is increasingly understood as a flexible outcome of sexual signalling rather than an evolutionary anomaly. In insects, such behaviours are often temporary, context dependent, and expressed alongside opposite-sex courtship. This pattern has led to increasing emphasis on condition-dependent mating filters, defined as how selectively individuals direct sexual signals toward potential mates. Here, I report a rare and, to my knowledge, first observation of male-directed sexual signalling in the house cricket ( Acheta domesticus ). In a video recorded during routine behavioural assays, an adult male produced sexual acoustic signals (courtship calls) toward another male. Simultaneously, this male directed aggressive signals toward other individuals within the same arena. This behaviour occurred under standardized laboratory conditions with a high-quality diet, ruling out nutritional stress as an explanation. Notably, the individuals involved originated from highly inbred laboratory lines, suggesting that extreme homozygosity may represent an overlooked source of variation influencing sexual signaling. This observation highlights the value of documenting rare behaviours and suggests new avenues for exploring the role of genetic context in mating filters and sexual communication.
Abstract The behavioural phenomenon of cooperation has been a focus of study in a variety of disciplines. Evolutionary anthropologists often use quantitative methods to test hypotheses on cooperation, grounded in theories such as kinship and reciprocal altruism: people are more likely to help those to whom they are related and who repay the cost of the altruistic act. That said, empirical results are somewhat mixed; numerous factors may cause social structures to vary across contexts. Here, we advance this line of inquiry in an underexplored freshwater fishery of the 179 300 km 2 Pantanal region in Brazil. In doing so, we examine the underlying structures of sociality within an economic-based support system at the household level ( ). Exponential random graph models reveal that households tend to engage in support with kin, nearby neighbours and reciprocal partners across the network. These results affirm longstanding evolutionary theories of cooperation while challenging preconceived assumptions regarding wealth differentials in offering and requesting aid; they may also inform debates on inequitable nature-based solutions in conservation, the practical implications of which could lead to better-adapted local policy interventions and feedback to communities to support regional initiatives.
Abstract Vocal imitation in oscine songbirds shows strong parallels with human speech development and provides a key model for investigating the behavioural and neural mechanisms of vocal learning. In zebra finches ( Taeniopygia castanotis ), young males acquire their song during a restricted sensitive period and typically require exposure to an adult tutor. While various artificial tutoring procedures have been tested — including playback and taxidermic stimuli — results have been mixed. Here, we report a study originally conducted in 2010, representing an early attempt to use a robotic conspecific as a song tutor in a developmental learning context. We revisit these data in light of more recent advances in robotic tutoring, which motivate their publication and reinterpretation. Nine brother pairs of juvenile males were exposed to a robotic tutor during the sensitive period, with one sibling assigned to a moving robot condition (MOV) and the other to a non-moving control (CON), both broadcasting the same song model. No significant difference in song imitation was found between groups. Birds exposed to the moving robot showed a tendency to spend more time near the robot, although this effect was not statistically significant and proximity decreased across sessions. Pecking at the robot was rare overall and showed only a weak, non-significant difference between groups. Correlational analyses indicated that song similarity was not associated with pecking or hopping behaviour; however, time spent near the robot was negatively correlated with song similarity. Taken together with recent studies, these findings indicate that behavioural salience alone is insufficient to explain variation in vocal learning outcomes in this paradigm. Instead, they suggest that effective robotic tutoring likely depends on additional factors such as biological realism, multimodal integration and contingent social interaction, helping to clarify the boundary conditions under which artificial agents can function as tutors.
Many bird species feed in flocks at the stop-over sites during the seasonal migration. The hierarchical organisation of single- and mixed-flocks results from the interactions occurring between individuals. We conducted an indoor experiment to study the interspecific dominance pattern among two species of migrating waders, common ringed plover (Charadrius hiaticula) and dunlin (Calidris alpina), when confronted with a single limited food source via 1 versus 1 trials for access to that food when in close spacing with each other. When analysing interspecific differences, we found common ringed plovers being clearly dominant over dunlins. At the individual level, all common ringed plovers occupied the top four positions within the dominance hierarchy of an experimental mixed-species wader flock consisting of 4 common ringed plovers and 9 dunlins. We suggest that this difference may be related to species-specific foraging strategies: common ringed plovers are visual foragers that prefer greater spacing from conspecifics and heterospecifics, whereas dunlins employ a tactile foraging method that may allow for closer proximity.
Reptiles are a vastly understudied taxon, leaving large gaps in comparative cognition and behaviour. They are more similar, cognitively, to mammals and birds than previously thought, but are difficult to test in cognitive tasks. The difficulty comes in effectively motivating reptiles to perform behaviours that allow for cognitive and behavioural comparison to mammals and birds. Painted turtles are a good model for comparison due to their relatively common use in scientific studies, compared to other reptiles, allowing them to be widely compared with mammals and birds. Methyl anthranilate (MA) is a potential short-term aversive stimulus in reptiles, similar to capsaicin in mammals, that could aid in motivating reptiles to perform cognitive tasks for comparison with mammals and birds. In this study, we tested MA on painted turtles to determine if it is an effective short-term aversive stimulus for use in behavioural and cognitive studies. We found that MA produces a short-term aversive reaction in painted turtles, exemplified by a decline in willingness to consume food treated with MA. Future comparative studies could benefit from using MA as an aversive stimulus in cognitive and behavioural tests on reptiles.
Comparative thanatology examines behavioural responses of animals to dead or dying individuals. In primates, most reports describe infant deaths, and accounts involving adults are rare. Here, we document the reactions of wild moor macaques (Macaca maura) to the corpse of an adult male, likely killed by vehicle collision, in South Sulawesi, Indonesia. The corpse was monitored with a camera trap for one week, from 1 to 8 April 2025. No macaques were recorded approaching the corpse on the day of death. On the following two days, multiple individuals of different sex and age classes visually inspected the body and produced vocalisations, including howls, barks, and loud calls. No physical contact with the corpse was recorded. From the fourth day onwards, only domestic dogs, jungle fowls, and Sulawesi warty pigs were observed around the corpse. In this case, moor macaques responded to the death of an adult conspecific mainly through visual and vocal behaviours. However, the absence of physical contact may relate to the decomposition state of the corpse when the macaques first encountered it or the possible lack of social bonds between the deceased individual and the recorded macaques.
Many animal species perform elaborate displays that represent honest signals of their physical qualities to potential mates and competitors. As such, these displays are targeted towards a specific audience and sensitive to their perception. But what happens when the signaller has a fundamentally different acoustic experience of the display as compared to their putative audience? We report observations from Fongoli, Senegal, of chimpanzees entering inside hollow baobab trees and performing acoustic displays. Only one chimpanzee enters at a time, and the sound to an outside audience appears dampened as compared to vocal and percussive signals performed on the outside of trees. We speculate that the sound may be modified and amplified within a hollow tree, so that the performer has a different experience of their display than does their audience, and encourage future empirical assessment. This behaviour represents one of only a few examples of nonhuman animals using objects or environmental features to modify their acoustic communication and is described for the first time in chimpanzees. Future research should address the motivations under lying chimpanzee baobab displays with a view to understanding potentially self-directed aspects of these performances.
Infanticide in Black-legged kittiwakes (Rissa tridactyla) has been reported only once. We report two adult kittiwakes killing chicks in an urban colony in northeast England. The first adult expelled all three chicks on its nest. The first chick to be expelled re-entered the nest and was killed nine days later by a neighbouring adult. The second chick expelled fell to its death. The third chick was attacked by the adult on the nest and left the nest cup. It later re-entered and then exited again following aggression and relocated to a neighbouring nest. This third chick then disappeared. We detail the behavioural sequences in these events and raise some tentative hypotheses about infanticide in this species.
