Grooming and Social Cohesion in Patas Monkeys and Other Guenons

Abstract

Patas monkeys (Erythrocebus patas), although ecologically distinct, share many features of social organization with the forest guenons including similar patterns of female-female relations and less rigid dominance hierarchies than is typical of other cercopithecines, notably baboons and macaques. Like many guenons, patas monkeys are female philopatric and females need to cooperate closely to defend their offspring and their group’s range and its resources. As patas monkeys and at least some guenons also cooperate in caring for infants, these species would seem to need to maintain strong social bonds. We examined the idea that grooming acts to maintain and reinforce social bonds in species like patas monkeys with rather loosely defined dominance relations. We analyzed grooming patterns of adult female patas monkeys in two wild groups, one small and one large, in Kenya’s Laikipia District. We looked at the effect of group size on grooming frequency. We found that, contrary to earlier predictions, females in the smaller group groomed all other group members and other adult females significantly more frequently than did females in the larger group. We also assessed the role of grooming in reaffirming social bonds under two sets of circumstances we believed would create a need for strong cooperation among group females: during intergroup encounters and also during a period when several females in the small study group disappeared. We found no significant effect of either of these potential causes of social stress on patas female grooming relations generally. Our analysis provided partial support for the idea that grooming acts in a general way to maintain or reaffirm social bonds in female philopatric species.