The Group Life Cycle and Demography of Brown Capuchin Monkeys (Cebus [apella] nigritus) in Iguazú National Park, Argentina

Abstract

This study reports demographic and social changes across 20 years in a population of brown capuchin monkeys living in Iguazu National Park in northeastern Argentina. Three sets of results emerge that are critical to understanding the evolution of social behavior in this population. First, patterns of age-related mortality clearly highlight certain periods of increased mortality (postnatal 6 months, onset of reproduction, late senescence) and near-perfect survival (2–6-year-old juveniles, young adult females). Second, tracking the migrations and rank-related reproductive strategies of males helps to uncover the causes and consequences of long male reproductive tenures that average 5 years. Finally, observations of relatively rare male takeovers of the alpha breeding position reveal a predictable sequence of stages in a group’s life cycle that tie together female fecundity, infanticide, group size, and kinship-based group fissions. These coordinated aspects of demography and kinship in different stages set the context for understanding differences between groups in social structure and organization.