Social Hierarchy and Dispersal in Free-Ranging Buffy-Headed Marmosets (Callithrix flaviceps)

Abstract

Behavior patterns in a large, free-ranging social group of buffy-headed marmosets (Callithrix flaviceps) were monitored over a 7-month period during which four adults – one male and three females – emigrated in two separate events. Social interactions such as play and allogrooming were relatively frequent, but agonistic interactions were rare, being observed, on average, less than twice per observation day for a group with between seven and ten adult members at any given time. With the exception of events involving the breeding female, intra-sexual ago- nism was almost non-existent between adults, and male→female aggression was five times more frequent than female→male. Absent between males and rare in females, submissive behavior was almost invariably directed by non-breeding females towards males and the breeding female. Taken together, these interactions point to a three- tiered social hierarchy within the group, with the breeding female in the top tier, followed by males in the second, and finally, non-breeding females. However, no one male was more dominant socially than any other, nor was any non-breeding female more subordinate. Male and female group members dispersed under different circumstances, but there is little evidence in either case to suggest that emigrations were a consequence of intra-group agonism, related to social rank or to competition for resources.