The Relation between Red Howler Monkey (Alouatta seniculus) Troop Size and Population Growth in Two Habitats

Abstract

No consensus yet exists to explain the diversity of primate social organization. Although ecological and social factors are both involved in the evolution and expression of social organization, they do not necessarily act together and may differ for the two sexes (Wrangham, 1987). Differing social factors usually are rooted in a species mating system— the degree of monopolization of mates by each sex—resulting from the effects of local ecology on the dispersion of the sex investing more in the production of offspring (Emlen and Oring, 1977; Vehrencamp and Bradbury, 1984). However, some features of primate social organization are phylogenetically conservative and resist change in response to varying ecological situations (Di Fiore and Rendall, 1994). At any given point in time, the particular social organization exhibited by a population also reflects recent demographic events (Altmann and Altmann, 1979; Dunbar, 1979). Among these life history variables are birth rates, which may vary directly in response to environmental variation, and sex ratios, which may vary randomly at birth but are affected thereafter by differential mortality (Dunbar, 1987). Social organization, then, is the result of a complex interplay of behavioral responses to ecological conditions, tempered by recent demographic events and constrained by phylogeny (Strier, 1994).