A Preliminary Field Study of the Moustached Tamarin Monkey (Saguinus mystax) in Northeastern Peru: Questions Concerned with the Evolution of a Communal Breeding System

Abstract

A preliminary field study was conducted on moustached tamarin monkeys (Saguinus mystax) inhabiting Padre Isla, a small island in the Amazon Basin of northeastern Peru. Data presented indicate that groups are generally composed of 3-8 individuals including a single breeding female, 1-3 reproductively active males, nonreproductive adult females, and offspring. Migration of adults and subadults into and out of established groups is common, and it is unlikely that S. mystax social units represent nuclear or extended families. It is argued that rather than tending towards monogamy, the reproductive biology and mating activities of moustached tamarins are better understood in terms of a communal breeding system. In the case of this and perhaps other callitrichid species, such a system appears to involve female promiscuity and the participation of reproductively active adult male group members in caring for the young. The hypothesis that there is an important relationship between the number of adult male ‘helpers’ and infant survival is discussed.