Seasonal changes in social cohesion among males in a same‐sex primate group

Abstract

Male-male interactions in mixed-sex groups of social mammals are typically characterized by a mix of hostility and affiliation, as a result of inherent conflicts over mating opportunities, and the costs and benefits of social alliances, co-operative behaviors, and coalitionary defense. In species of nonhuman primates that form all-male groups, it is still unclear how the tradeoffs between the benefits of forming an all-male group and the cost of male-male competition in seeking mating opportunities with females in bisexual groups influence social cohesion in different seasons. Here, we used social network analysis to quantify the impact of reproductive seasonality on social cohesion and clique size of bachelor males residing in an all-male unit (AMU) in wild black-and-white snub-nosed monkeys (Rhinopithecus bieti). These primates are strict seasonal breeders and live in a modular social system composed of a number of one-male units (OMUs) and an associated peripheral AMU. We found that the AMU social network had a significantly lower density, centralization, clustering coefficient, and smaller clique size during the mating season compared to the non-mating period. However, aggression among AMU males during both mating and non-mating periods was low. Our results suggest that network structure topology in male same-sex social units is modulated by seasonal changes. Bachelor males engage in two types of competition to gain reproductive success: first, which is analogous to contest competition, in which bachelor males act aggressively and challenge OMU leader males in an attempt to take over an OMU; and second, which is more analogous to scramble competition, in which bachelor males avoid aggressive interactions and instead engage in sneaky copulations with fertile females. Our work adds to an understanding of the maintenance of all-male groups in species that form a multilevel society.

Male–male social bonding, coalitionary support and reproductive success in wild Guinea baboons

“…Guinea baboon males appear to face a trade-off between investments in same-sex and opposite-sex bonds, and the investment in different types of bonds varies with life-history stage: young and old bachelor males invest more in same-sex relationships, but turn their attention to females once they have become primary males—at the expense of time available for their male ‘friends’. Similar effects are seen in male Barbary macaques ( Macaca sylvanus ) and snub-nosed monkeys ( Rhinopithecus bieti ) across seasons, where investment in male—male affiliative relationships drops during the mating season [57,58].…”

Male-Male Social Bonding, Coalitionary Support and Reproductive Success in Wild Guinea Baboons

“…Guinea baboon males appear to face a trade-off between investments in same-sex and opposite-sex bonds, and the investment in different types of bonds varies with life-history stage: young and old bachelor males invest more in same-sex relationships, but turn their attention to females once they have become primary males at the expense of time available for their male Similar effects are seen in male Barbary macaques (Macaca sylvanus) and snubnosed monkeys (Rhinopithecus bieti) across seasons, where investment in male-male affiliative relationships drops during the mating season [57,58].…”

Social security: can rattlesnakes reduce acute stress through social buffering?

“…The type of social organization (e.g., mating system and group size), however, can influence both the presence of social buffering and which conspecifics demonstrate the ability to buffer (Hennessy et al, 2009). Many species undergo seasonal shifts in social organization (Rowell and Dixson, 1975;Zhu et al, 2018), but it remains untested whether such a shift also modulates the social buffering response. Mating occurs for C. helleri in February-April and August-October, with females giving birth between August and mid-October (Klauber, 1972;Dugan et al, 2008).…”