Kin recognition versus familiarity in a solitary mustelid, the European polecat Mustela putorius

Social organization of otters in relation to their ecology

Otter species are known to fluctuate intraspecifically from a solitary lifestyle to group-living arrangements. By examining what is known about habitat use and foraging style in otters of 13 different species, based on 93 studied sites, we assessed (1) the relationship between social habits and preferred habitats, (2) the relationship between species and prey preferences, and (3) the effect of predator avoidance on their social organization in order to assess the socio-ecological factors influencing otters. Females remain the core of their social stability. We show the major influence of habitats and feeding strategies (i.e. socio-ecology) of otters. The different species of solitary otters most often inhabit linear environments, such as freshwater ecosystems or wave-exposed marine coasts, and their habitat is often subject to disturbances that fragment their functional continuity. Social otters are more often found in extensive habitats with high plant cover, regular food resources and in areas with large predators compared to solitary species. The maintenance of regular resources and the fact that the main trophic resources are replenished rapidly might be determining factors driving sociality. Group-living and bachelor congregations among otters can also respond to pressure from large predators. This suggests that foraging, habitat use and the presence of large predators may be the drivers of sociality in otters. We conclude that most otters have a greater social potential than previously assumed, which is confirmed by their various vocalizations recently described.

Evolutionary Pathways to Communal and Cooperative Breeding in Carnivores

In animal societies, individuals can cooperate in a variety of tasks, including rearing young. Such cooperation is observed in complex social systems, including communal and cooperative breeding. In mammals, both these social systems are characterized by delayed dispersal and alloparenting, whereas only cooperative breeding involves reproductive suppression. While the evolution of communal breeding has been linked to direct fitness benefits of alloparenting, the direct fitness cost of reproductive suppression has led to the hypothesis that the evolution of cooperative breeding is driven by indirect fitness benefits accrued through raising the offspring of related individuals. To decipher between the evolutionary scenarios leading to communal and cooperative breeding in carnivores, we investigated the coevolution among delayed dispersal, reproductive suppression, and alloparenting. We reconstructed ancestral states and transition rates between these traits. We found that cooperative breeding and communal breeding evolved along separate pathways, with delayed dispersal as the first step for both. The three traits coevolved, enhancing and stabilizing one another, which resulted in cooperative social systems as opposed to intermediate configurations being stable. These findings promote the key role of coevolution among traits to stabilize cooperative social systems and highlight the specificities of evolutionary patterns of sociality in carnivores.

Similarity between an unfamiliar human and the owner affects dogs' preference for human partner when responding to an unsolvable problem

This study investigates whether dogs are able to differentiate between people according to whether or not they show similarities to their owners. We hypothesized that dogs would show a preference for the "similar" partner when interacting with unfamiliar humans. After having familiarized with two experimenters displaying different degrees of similarity to their owners, dogs (N = 36) participated in a situation where the desired toy object was made inaccessible in order to find out whether they initiate interaction with the two partners differently. Two different types of "similarity cues" were used (either alone or combined with each other): (1) persistent behavioral characteristics (i.e., familiar vs. strange motion pattern and language usage) and (2) an unfamiliar arbitrary group marker (i.e., one of the potential helpers was wearing clothing similar to that worn by the owner). Results show that although dogs payed equal attention to the human partners displaying various types of similarity to their owners during familiarization, they exhibited a visual attention preference for the human whose motion pattern and language usage were similar to their owner's in the inaccessible-toy task. However, there was weak evidence of discrimination based on the arbitrary group marker (clothing). Although dogs' different tendencies to interact with the potential helpers do not necessarily imply an underlying ability to create social categories based on the degree of similarity between the owner and unfamiliar people, these results suggest that functionally human infant-analogue forms of social categorization may have emerged in dogs.

Behavioural Profiles of Brown and Sloth Bears in Captivity

Three brown bear (Ursusarctosarctos) individuals and two sloth bear (Melursusursinusinornatus) individuals were observed in captivity to produce behavioural profiles for each individual. Data collected through behavioural observations were used to produce activity budgets, and to identify space usage and certain aspects of social behavior. Behaviour monitoring allowed the researchers to evaluate the welfare of the animals by identifying the occurrence of stereotypic behaviours, which are sometimes associated with stress. Behavioural profiles were created using data obtained through behavioural observations (coding) and keeper questionnaires (rating). The behavioural observations indicated a number of stereotypic behaviours in sloth bears but not in brown bears. The uniformity of zone usage was calculated to investigate if the enclosure size and features were adequate for use, and a social aspect of otherwise solitary animals was also identified. The behavioural profiles generated through coding and rating were compared to determine the reliability between these two methods in Ursids. Profiles were not compared between individuals since this study is not a comparison between different personality types but rather an effort (one of the few ones existing in literature) to select a valid and reproducible methodology capable of assessing personality in bears.

Male rhesus macaques use vocalizations to distinguish female maternal, but not paternal, kin from non-kin

Recognizing close kin and adjusting one's behavior accordingly (i.e., favor kin in social interactions, but avoid mating with them) would be an important skill that can increase an animals' inclusive fitness. Previous studies showed that philopatric female rhesus macaques (Macaca mulatta) bias their social behavior toward maternal and paternal kin. Benefits gained from selecting kin should, however, not only apply to the philopatric sex, for which the enduring spatial proximity facilitates kin discrimination. Given that dispersal is costly, the dispersing sex may benefit from migrating together with their kin or into groups containing kin. In male rhesus macaques, natal migrants bias their spatial proximity toward familiar male kin rather than familiar non-kin. Here, we set up playback experiments to test if males use the acoustic modality to discriminate familiar female kin from non-kin in a non-sexual context. Males responded differently to the presentation of "coo" calls of related and unrelated females, with their reaction depending on the interaction between kin-line (maternal vs paternal kin) and degree of relatedness (r = 0.5, 0.25). Specifically, males were more likely to respond to close kin compared to more distant kin or unrelated females, with this effect being significant in the maternal, but not paternal kin-line. The present study adds to our knowledge of kin recognition abilities of the dispersing sex, suggesting that male rhesus macaques are also able to identify kin using the acoustic modality. We discuss that the probability of response might be affected by the potential benefit of the social partner.

Inbred and furious: negative association between aggression and genetic diversity in highly inbred fish

Aggressive behaviour plays an important role in securing resources, defending against predators and shaping social interactions. Although aggression can have positive effects on growth and reproductive success, it is also energetically costly and may increase injury and compromise survival. Individual genetic diversity has been positively associated with aggression, but the cause for such an association is not clear, and it might be related to the ability to recognize kin. To disentangle the relationships between genetic diversity, kinship and aggression, we quantified aggressive behaviour in a wild, self-fertilizing fish (Kryptolebias marmoratus) with naturally variable degrees of genetic diversity, relatedness and familiarity. We found that in contrast to captive fish, levels of aggression among wild K. marmoratus are positively associated with individual homozygosity, but not with relatedness or familiarity. We suggest that the higher aggression shown by homozygous fish could be related to better kin discrimination and may be facilitated by hermaphrodite competition for scarce males, given the fitness advantages provided by outcrossing in terms of parasite resistance. It seems likely that the relationship between aggression and genetic diversity is largely influenced by both the environment and population history.

Social partner discrimination based on sounds and scents in Asian small-clawed otters (Aonyx cinereus)

Ability to discriminate familiar conspecifics is an essential competence in any group-living species, ensuring socio-spatial cohesion, but in many animals, such as mustelids, the relative importance of the different communicative modalities for discrimination is poorly understood. In otters, there is evidence of intra-specific variation in physical appearance and in feces chemical profile, but the potential for acoustic identity coding as well as for identity decoding in visual, acoustic and olfactive domains remains unexplored. We investigated the acoustic structure of contact calls in five captive groups of small-clawed otters and found that it is possible to reliably assign one particular call to a given adult male caller. Females discriminated between familiar and unfamiliar adult males based on their sound (playback) and smell (feces) but not based on their picture, suggesting abilities to memorize and use acoustic and olfactive signatures in their daily social life.

Man's underground best friend: domestic ferrets, unlike the wild forms, show evidence of dog-like social-cognitive skills

Recent research has shown that dogs’ possess surprisingly sophisticated human-like social communication skills compared to wolves or chimpanzees. The effects of domestication on the emergence of socio-cognitive skills, however, are still highly debated. One way to investigate this is to compare socialized individuals from closely related domestic and wild species. In the present study we tested domestic ferrets (Mustela furo) and compared their performance to a group of wild Mustela hybrids and to domestic dogs (Canis familiaris). We found that, in contrast to wild Mustela hybrids, both domestic ferrets and dogs tolerated eye-contact for a longer time when facing their owners versus the experimenter and they showed a preference in a two-way choice task towards their owners. Furthermore, domestic ferrets, unlike the wild hybrids, were able to follow human directional gestures (sustained touching; momentary pointing) and could reach the success rate of dogs. Our study provides the first evidence that domestic ferrets, in a certain sense, are more dog-like than their wild counterparts. These findings support the hypothesis that domestic species may share basic socio-cognitive skills that enable them to engage in effectively orchestrated social interactions with humans.