Abstract: We investigated dyadic grooming relationships in a captive group of bonobos (Pan paniscus) and questioned what social function grooming fulfils in the 'market of services and favors'. Hereto we examined which of two theoretical models – grooming for support (Seyfarth, 1977, 1980) or grooming according to the similarity principle (de Waal & Luttrell, 1986) – best accounted for the observed grooming distribution. Similarity in traits did not correlate with increased grooming or close proximity among the individuals. Therefore, the similarity hypothesis was rejected. Seyfarth's model of rank-related grooming was largely confirmed. The animals distributed their grooming according to the rank of the receivers. We found an exchange between grooming and receipt of support. There was more grooming up than down the hierarchy. However, not all predictions about rank-related competition over grooming were confirmed. We found that dyadic grooming reciprocity indeed increased with decreasing rank distance. Yet, there was no increase of grooming within the dyad with decreasing rank distance and high ranking individuals were not competed over at the highest rates. The observed correlation between grooming and support received represents an important fit with Seyfarth's prediction, but does not allow for conclusions about underlying causal processes. Other causal explanations, besides the 'groom to receive support' hypothesis, that could explain a similar correlation are discussed.

Abstract: African wild dog (Lycaon pictus) pup vocalizations were studied in Hwange National Park, Zimbabwe for weeks 3 through 7 of the socialization period. Here we present the vocal repertoire, including the use of repetitive and mixed sounds, and investigate the extent to which the emerging sound system of Lycaon conforms to predicted design features of Morton's (MS) motivation-structural rules. Features of the pup sound system are highlighted by comparison with adults and other social canids.TAGSTARTBRTAGEND Data were collected at three den sites (litter sizes: 8, 8, and 9) of two study packs. A total of 1903 vocalizations were classified, and eight vocal classes and seven subclasses were identified. Although all sounds identified persist into adulthood, observations indicate a delayed onset in some vocal classes, including both the lowest (i.e. rumbles) and highest (i.e. twitters) frequency sounds. As predicted by the (MS) model, pups invested heavily in high frequency, harmonic care/social soliciting sounds (91%, N = 1586 unmixed vocalizations), however, no clear association between acoustic structure and sound repetition was found. Significantly more repetition was heard in all vocal classes with the exception of moans and barks. Intra-pack aggression is generally muted in this obligate social carnivore suggesting that repetition may be a low cost strategy to induce social outcomes and obtain food. The patterning of mixed vocalizations (N = 317) was consistent with the (MS) model. Given the high degree of cooperation necessary for individual survival, the predominant use of cross-mixed sounds may serve to minimize conflict as pups begin to form relationships with littermates and adults. Noisy/noisy sounds were exceptionally rare. Comparative data suggest a relationship between the early patterning of mixed sounds and species-specific social organization in canids.

Abstract: 1. The social relationships in a group of Icelandic horses without a mature stallion were studied. The horses were all familiar to each other. Mutual grooming and play relationships, spatial associations, dominance-subordinate relations and the effect of kinship on these relationships were analysed.TAGSTARTBRTAGEND 2. The social structure was clearly dominated by the behaviour of the adult mares. The horses preferred to form bonds within their social class (sex/age) and they kept close proximity with their friends. The group was effectively divided into two social subgroups, adult mares as one group and adult geldings and sub-adults as another group. The sub-adults and adult geldings formed associations, which were based on mutual grooming and play, while the adult mares did not play. Differences between the sexes were evident. Males played more than the females, had more playing partners and were more popular as playmates.TAGSTARTBRTAGEND 3. Aggression rates were low. The dominance hierarchy was linear. Adult mares ranked higher than adult geldings, sub-adults and the foals. Rank was significantly correlated with age. The closer the adult mares were in rank, the more they groomed with each other. Such relationships were not found amongst the other social group.TAGSTARTBRTAGEND 4. Kinship was calculated between all pairs of animals for up to 4 or 5 generations. Allogrooming and play frequencies and proximity were all positively correlated with kinship. Adult mares, which were close in the dominance hierarchy, were on average more related than those further apart.TAGSTARTBRTAGEND 5. The social relationships in the Icelandic herd were, to some extent, different from relationships reported from unmanaged and feral horse-herds with mature stallions and bachelors. Our results suggest that adult mares groom more in groups without a stallion. Furthermore, they have more preferred partners than in natural harems and their partners are other adult mares, not their weaned offspring as seems to be the case in feral herds. The sub-adults also seem to be more socially active in the absence of stallions. Interestingly, in the Icelandic group, the adult mares showed stallion like behaviours, like mounting and protecting foals. Only by studying the behaviour and the nature of the relationships of horses in groups of different compositions, can we expect to gain a comprehensive understanding about individual social strategies and cognitive capabilities of the species. Such knowledge is valuable for management and welfare of the horse.

Abstract: Many mammalian species are highly social, creating intra-group competition for such things as food and mates. Recent research with nonhuman primates indicates that in competitive situations individuals know what other individuals can and cannot see, and they use this knowledge to their advantage in various ways. In the current study, we extended these findings to a non-primate species, the domestic goat, using the conspecific competition paradigm developed by Hare et al. (2000). Like chimpanzees and some other nonhuman primates, goats live in fission-fusion societies, form coalitions and alliances, and are known to reconcile after fights. In the current study, a dominant and a subordinate individual competed for food, but in some cases the subordinate could see things that the dominant could not. In the condition where dominants could only see one piece of food but subordinates could see both, subordinates' preferences depended on whether they received aggression from the dominant animal during the experiment. Subjects who received aggression preferred the hidden over the visible piece of food, whereas subjects who never received aggression significantly preferred the visible piece. By using this strategy, goats who had not received aggression got significantly more food than the other goats. Such complex social interactions may be supported by cognitive mechanisms similar to those of chimpanzees. We discuss these results in the context of current issues in mammalian cognition and socio-ecology.