Male-Male Social Relationships in Wild White-Faced Capuchins, Cebus Capucinus

Abstract

Male white-faced capuchins are expected to have tense, yet cooperative, relationships because they must compete for matings in an intragroup context, yet males of the same group need one another's support for intergroup competition for mates. In this paper, I examine in detail the social relationships of the 4 adult males in a single social group of wild white-faced capuchins at Lomas Barbudal Biological Reserve, Costa Rica. There was a clear alpha male, to whom all other males deferred; however, there was no obvious linear ranking among the subordinate males. Urine rubbing and branch displays were performed more often by the alpha than by subordinate males, though one subordinate male increased his rates of these behaviours when the alpha male was out of view. The alpha male formed coalitions with subordinate males against other males, but pairs of subordinate males never formed coalitions against the alpha male. The alpha male was not consistent with regard to which subordinate male he supported in triadic interactions. Affiliative interactions between subordinate males were consistently disrupted by the alpha male. Males cooperated with one another in the context of defense against predators and defense against males of other social groups. Relaxed affiliation and close proximity between males were rare, in comparison with male-female and female-female dyads. Tense affiliation (e.g. wheeze dances, play, and rough grooming) was most common following a change in alpha male, when aggressive interactions were also more common. Despite males' relatively low rates of affiliation and proximity, males actively searched for one another when a male was missing from the group for an extended period of time.