Collective Action and Male Affiliation in Howler Monkeys (Alouatta caraya)

Abstract

Traditional models of primate socioecology highlight female within-group feeding competition and aggression over limited food resources as a primary driver of primate social interactions. In this regard several authors have argued that within-group feeding competition is a pervasive cost of social group living, and that individuals should live in groups that are small enough to avoid the costs of aggression at feeding sites and large enough to benefit from predator detection and reduced infanticide risk. In this paper we present data based on a 21 month field investigation in Argentina of within-group social tolerance, cooperation, collective action, and mating strategies of male black and gold howler (Alouatta caraya) monkeys in Argentina. We argue that models of primate socioecology based on within-group reproductive and feeding competition derived from studies of Old World primates fail to adequately explain within-group male affiliation, mating strategies, and collective action in many taxa of New World primates. Our data on Alouatta caraya indicate that resident males are highly tolerant of each other across a range of contexts including feeding, foraging, resting, and mating. In A. caraya, males were often each other’s nearest neighbor or preferred associate, and engaged in bouts of intrasexual grooming and embracing. We argue that concepts of reciprocity, mutualisms, and the benefits of collective action are central to an understanding of social tolerance and cooperative behavior among male black and gold howler monkeys (Alouatta caraya). We argue that although individuals may compete for access to reproductive partners, greater attention needs to be paid to the role of non-aggressive behavior such as sperm competition, socioendocrinological mechanisms of reproductive suppression, female mate choice, and the advantages to both males and females of living in a more effectively functioning social group in evaluating the costs and benefits to individual males and females of cooperative and collective behavior.