Animal Behaviour

Transmitting information about the location of a predator in social animal species can be seen as an investment in a public good, where information is the resource and group members benefit from reduced fatalities of kin and cooperation partners in their community. As few empirical tests of this idea exist in natural settings, we conducted a field experiment using snake models in wild sooty mangabeys, Cercocebus atys atys . We tested sooty mangabey alarm-calling patterns when exposed to viper models, investigating whether individuals called to signal fitness, to warn specific group members, or when information about the threat is not public, as would be predicted by public goods games...

The benefits of group living have traditionally been attributed to risk dilution or the efficient exploitation of resources; individuals in social groups may therefore benefit from access to valuable information. If sociality facilitates access to information, then individuals in larger groups may be predicted to solve novel problems faster than individuals in smaller groups. Additionally, larger group sizes may facilitate the subsequent spread of innovations within animal groups, as has been proposed for human societies...

In social animals, affiliative behaviours bring many benefits, but also costs such as disease risk. The ways in which affiliation may affect the risk of infectious agent transmission remain unclear. Moreover, studies linking variation in affiliative interactions to infectious agent incidence/diversity have speculated that disease transmission may have occurred, rather than revealing that transmission did occur. We address these gaps using the phylogenetics of commensal gut Escherichia coli to determine whether affiliative grooming and huddling social networks mediated microbial transmission among rhesus macaques...

Larval-derived nutritional reserves are essential in shaping insects' adult fitness. Early larval instars of many Lepidopteran species are often sessile, and the conditions experienced by these larvae are often highly dependent on the mother's oviposition choice. Later larval stages are more mobile and therefore can choose their food whenever alternatives are available. We tested how feeding on a drought-exposed host plant impacts life history in an insect herbivore, and whether the observed responses depended on developmental stage...

Network analysis has driven key developments in research on animal behaviour by providing quantitative methods to study the social structures of animal groups and populations. A recent formalism, known as multilayer network analysis , has advanced the study of multifaceted networked systems in many disciplines. It offers novel ways to study and quantify animal behaviour through connected 'layers' of interactions. In this article, we review common questions in animal behaviour that can be studied using a multilayer approach, and we link these questions to specific analyses...

Differential allocation occurs when individuals alter their reproductive investment based on their mate's traits. A previous study showed that male threespine sticklebacks, Gasterosteus aculeatus , reduced courtship towards females that had previously been exposed to predation risk compared to unexposed females. This suggests that males can detect a female's previous history with predation risk, but the mechanisms by which males assess a female's history are unknown. To determine whether males use chemical and/or visual cues to detect a female's previous history with predation risk, we compared rates of courtship behaviour in the presence of visual and/or olfactory cues of predator-exposed females versus unexposed females in a 2×2 factorial design...

Imperfect mimicry presents a paradox of incomplete adaptation - intuitively, closer resemblance should improve performance. Receiver psychology can often explain why mimetic signals do not always evolve to match those of their models. Here, we explored the influence of a pervasive and powerful cognitive bias where associative learning depends upon an asymmetric interaction between the cue (stimulus) and consequence (reinforcer), such as in rats, which will associate light and tone with shock, and taste with nausea, but not the converse...

The specialization of individuals in specific behavioural tasks is often attributed either to irreversible differences in development, which generate functionally divergent cooperative phenotypes, or to age-related changes in the relative frequency with which individuals perform different cooperative activities; both of which are common in many insect caste systems. However, contrasts in cooperative behaviour can take other forms and, to date, few studies of cooperative behaviour in vertebrates have explored the effects of age, adult phenotype and early development on individual differences in cooperative behaviour in sufficient detail to discriminate between these alternatives...

To understand how natural selection may act on cognitive processes, it is necessary to reliably determine interindividual variation in cognitive abilities. However, an individual's performance in a cognitive test may be influenced by the social environment. The social environment explains variation between species in cognitive performances, with species that live in larger groups purportedly demonstrating more advanced cognitive abilities. It also explains variation in cognitive performances within species, with larger groups more likely to solve novel problems than smaller groups...

Puppy packs (consisting of only puppies) and mixed-age packs (composed of puppies and adults) were observed to test whether social play can be used for assessing and establishing social relations in wolves, Canis lupus . Differently from previous studies, we looked at play behaviours in detail, allowing us to categorize play interactions as either competitive or relaxed, and predicted that different types of play would be associated with different relationships between individuals. We found that the more time dyads spent in relaxed play, the more affiliative interactions they exchanged outside of play...

Extragroup paternity (EGP) is found across a wide range of species and may entail reproductive benefits, but may also entail costs to both sexes. While population and group parameters affecting the degree of EGPs are relatively well established, less is known about the individual characteristics that make males and females engage in alternative reproductive tactics such as EGP. Applying a combination of long-term demographic and genetic data from the rhesus macaque population of Cayo Santiago (Puerto Rico, U...

Many animals actively defend their offspring using a range of behaviours from calling and mobbing in birds, to physical grappling in crustaceans, and the expression of these behaviours positively scale with offspring value. While this role of behaviour in defence is well studied, very little is known about how other traits, specifically the structure of architectural constructions such as webs and nests, contribute to offspring defence. Additionally, although some tax a show consistent individual differences in offspring defence behaviour, it is completely unknown whether individuals also differ in defensive structures...

•We reinvestigate a new model based on the handicap hypothesis.•We show the handicap hypothesis does not explain male dimorphisms.•The results are due to the 'playing-the-field' assumption of the model.•The generality of the 'playing-the-field' assumption is suspect.•The evolutionary stability of the proposed new equilibrium is questionable.

Animals must identify reliable cues amidst environmental noise during learning, and the cues that are most reliable often depend on the local ecology. Comparing the performance of populations of the same species across multiple versions of a cognitive task can reveal whether some populations learn to use certain cues faster than others. Here, using a criterion-based protocol, we assessed whether two natural populations of sticklebacks differed in how quickly they learned to associate two different discrimination cues with the location of food...

Fitness costs of incubation ensue whenever the trade-off between incubation and foraging leads to suboptimal incubation or decreased parental body condition. We examined the costs of incubation in a wild population of house wrens, Troglodytes aedon , by experimentally extending or decreasing the incubation period by cross-fostering eggs between nests at different stages of incubation (eggs from control nests were cross-fostered at the same stage of incubation). We determined whether parents or offspring bear the costs of incubation by measuring effects on females and offspring within the same breeding season during which the manipulation occurred, but also by evaluating potential trade-offs between current and future reproduction by monitoring return rates of experimental females and recruitment rates of offspring in subsequent breeding seasons...

In cooperatively breeding species, encounters with intruders may serve multiple functions ranging from reaffirming group territory ranges to facilitating assessments for additional breeding opportunities. While these distinctive events offer the opportunity to investigate the delicate balance of these social dimensions within animal societies, their unpredictable occurrence makes witnessing and controlling these events in the wild particularly challenging. Here we used a field playback approach to simulate conspecific territorial incursions in cooperatively breeding common marmosets ( Callithrix jacchus ) to distinguish between the three following non-mutually exclusive functions of intergroup encounters in this species of New World primate: territorial defense, mate defense, and assessment of breeding opportunities...

Network dynamics can reveal information about the adaptive function of social behaviour and the extent to which social relationships can flexibly respond to extrinsic pressures. Changes in social networks occur following changes to the social and physical environment. By contrast, we have limited understanding of whether changes in social networks precede major group events. Permanent evictions can be important determinants of gene flow and population structure and are a clear example of an event that might be preceded by social network dynamics...

In mammals, and especially primates, group size and social complexity are typically correlated. However, we have no general explanation why this is so. I suggest that the answer may lie in one of the costs of group living: mammalian reproductive endocrinology is extremely sensitive to stress, and forms one of the hidden costs of living in groups. Fertility declines with group size widely across the social mammals, including primates, and will ultimately place a constraint on group size. However, some species seem to have been able to mitigate this cost by forming bonded relationships that reduce the impact of experienced aggression, even if rates of aggression remain high...

There is much experimental evidence suggesting that chimpanzees understand that others see. However, previous research has never experimentally ruled out the alternative explanation that chimpanzees are just responding to the geometric cue of 'direct line of gaze', the observable correlate of seeing in others. Here, we sought to resolve this ambiguity by dissociating seeing from direct line of gaze using a mirror. We investigated the frequency of chimpanzees' visual gestures towards a human experimenter who could see them (as a result of looking into a mirror) but who lacked a direct line of gaze to them (as a result of having his/her head turned away)...

Animals are commonly exposed to multiple environmental stimuli, but whether, and under which circumstances, they can attend to multiple stimuli in multitask learning challenges is elusive. Here, we assessed whether simultaneously occurring chemosensory stimuli interfere with each other in a dual-task learning challenge. We exposed predatory mites Neoseiulus californicus early in life to either only conspecifics (kin) or simultaneously conspecifics (kin) and food (thrips or pollen), to determine whether presence of food interferes with social familiarization and, vice versa, whether presence of conspecifics interferes with learning the cues of thrips...