Abstract: The relational model of conflict resolution predicts that after an aggressive conflict there should be a motivational shift from aggression to attraction. Most tests of the reconciliation hypothesis assume, however, that all non-aggressive post-conflict behaviours between former opponents are motivationally homogeneous and qualify as friendly reunions. In fact, although the hypothesis predicts an increased occurrence of friendly contacts after conflicts, in practice, however, post-conflict reunions often include a mixture of contact and non-contact behaviours. Most reconciliation studies either (often) assume a conciliatory function for post-conflict reunions or (less often) test functional predictions. Finally, the valuable relationships hypothesis predicts that conciliatory rates should be relatively higher between friends and allies than between non-friends/allies. In this paper, we use data on non-aggressive interactions following conflicts between adult male hamadryas baboons that are neither friends nor allies to assess the implications of all these important but largely overlooked issues. The analyses of the rate and temporal relation of non-contact greeting (NCTG) to anxiety-related behaviours and side-directed aggression as well as of the behaviours used during non-aggressive interactions with male and female third-parties suggest that the NCTG used by males after conflicts were neither motivationally friendly nor functionally conciliatory. We point out that the gestures exchanged during these post-conflict NCTG can be interpreted as formalized signals of equal status and that the rate and form of the greetings used by male opponents are indicative of high relationship insecurity and incompatibility respectively. We conclude that although male hamadryas' post-conflict NCTG are not conciliatory they may serve to assess their opponents' attitude and to negotiate the restoring of their pre-conflict levels of peaceful but non-amicable co-existence.

Abstract: Abstract  Researchers have often explained order of progression of group members during joint movement in terms of the influence of ecological pressures but rarely that of social constraints. We studied the order of joining by group members to a movement in semifree-ranging macaques with contrasting social systems: 1 group of Tonkean macaques (Macaca tonkeana) and 1 group of rhesus macaques (M. mulatta). We used network metrics to understand roles and associations among individuals. The way the macaques joined a movement reflected the social differences between the species in terms of dominance and kinship. Old and dominant male rhesus macaques were more often at the front of the movement, contrary to the Tonkean macaques, which exhibited no specific order. Moreover, rhesus macaques preferred to join high-ranking or related individuals, whereas Tonkean macaques based associations during joining mostly on sexual relationships with a subgroup of peripheral males.

Abstract: Gestures and facial displays are involved in regulating many aspects of mammal social life such as aggression, dominance-subordinate relationships, appeasement and play. Playful activity is an interesting behaviour for examining the role of signals as intentional communication systems. When animals play they perform patterns that are used in other serious contexts. To avoid miscommunication, many species have evolved signals to maintain a playful mood. Bonobos, Pan paniscus, with their flexible social relationships and playful propensity, may represent a good model species to test some hypotheses on adult play signalling. I analysed the potential roles of facial play expressions and solitary play in soliciting and regulating social play and found that adult bonobos used the play face (relaxed open-mouth display) in a selective manner. Play faces were more frequent during social than solitary play and, within social play, polyadic sessions (even though less frequent than dyadic sessions) were characterized by a higher frequency of signals. Following the rule of play intensity matching, play faces were more frequent when the two players matched in age and size (sessions among adults). Moreover, among dyads there was a positive correlation between the frequency of aggressive interactions performed and the frequency of play signals used, thus suggesting that signals are crucial in play negotiations among individuals showing high baseline levels of aggression. Finally, solitary play, especially when it involved pirouettes and somersaults, had an important role in triggering social play.

Abstract: Reconciliation is defined as the first postconflict affinitive contact between former opponents. While reconciliation in anthropoid primates has been widely investigated, few studies have focused on postconflict mechanisms in prosimians, and only in captivity. Unlike anthropoids, Malagasy prosimians show female dominance, lack of sexual dimorphism and seasonal breeding. However, they share features with anthropoids such as cohesive societies, female philopatry and individual recognition. Comparing social prosimians with anthropoids is crucial for understanding the evolution of reconciliation dynamics. Here we present the first study on reconciliation in a wild prosimian. We focused on the Propithecus verreauxi (sifaka) of the Berenty forest (southern Madagascar). We examined postconflict behaviour in the light of theoretical expectations based on potential costs and benefits of the individuals involved. Our results indicate that P. verreauxi can evaluate possible risks and benefits of engaging in postconflict reunions. Victims were most likely to interact affinitively with the aggressor after low-intensity aggression. Moreover, only the conflicts occurring outside the feeding context were reconciled. Such results are consonant with the fact that, in P. verreauxi, social dominance is translated more into feeding priority than into a framework of despotic relationships. In agreement with the valuable relationship hypothesis, P. verreauxi were more likely to reconcile with valuable partners: reconciliation preferentially occurred between subordinates and top-ranking individuals, and between animals sharing good relationships (high levels of affinitive behaviours). Over the short term, reconciliation in P. verreauxi seems to have an important role in reducing the probability of further attacks by the aggressor.

Abstract: Abstract Hormones play a central role in the physiology and behaviour of animals. The recent development of noninvasive techniques has increased information on physical and social states of individuals through hormone measurements. The relationships among hormones, life history traits and behaviours are, however, still poorly known. For the first time, we evaluated natural winter glucocorticoid and testosterone levels in young ungulates in relation to winter progression, diet quality and social rank. Overwinter, levels of glucocorticoid and testosterone decreased, possibly due to the decline of fawns" body mass. The relationships between hormone levels and diet quality were surprising: Fawns fed the control diet presented higher glucocorticoid and lower testosterone levels then fawns fed the poor diet, suggesting that control fawns faced a higher nutritional stress than those on the poor diet. Similarly to other studies on social mammals, we found no relationship between faecal glucocorticoid levels and social rank, suggesting that social stress was similar for dominant and subordinate fawns during winter. Testosterone levels were not correlated to social rank as found previously in groups of individuals forming stable social hierarchies and maintaining stable dominance relationships. The simultaneous suppression of glucocorticoid and testosterone levels suggests for the first time that young ungulates present a hormonal strategy to prevent fast depletion of limited proteins and fat resources during winter.