The effects of forest fragmentation on primates in the Brazilian Amazon

Abstract

Forest fragmentation, arising from deforestation, is a primary threat to primate conservation; however, species do not respond to fragmentation in the same manner. This dissertation examines how forest fragmentation affected 1) the distribution and persistence of six primate species and 2) the behavioral ecology of the northern bearded saki monkey (Chiropotes sagulatus). Research was conducted at the Biological Dynamics of Forest Fragments Project, located approximately 80 km north of Manaus, Amazonas, Brazil. Nine forest fragments and two areas of continuous forest were surveyed for primates from July-August 2003 and January 2005-June 2006. Fragment attributes (e.g., size, isolation, matrix attributes) were determined using satellite images. Although some species e.g., red howler monkey, Alouatta seniculus) were common in the forest patches, other species (e.g., black spider monkey, Ateles paniscus) were rarely present. Primate species richness was predicted by fragment size, distance to closest forest patch greater than 0.5 ha, and proportion of secondary growth in the matrix, but primate characteristics (e.g., body size, home range, degree of frugivory) did not predict species presence in the fragments. Although the bearded saki monkey is a medium-size, highly frugivorous monkey with a large home range, it was present in forest fragments less than 5% of the species' home range size in continuous forest. Each bearded saki group was followed for three consecutive days during each data cycle. Every five minutes, the location and behavior of the monkeys were recorded. Monkeys in the small forest fragments had smaller group sizes, smaller day ranges, different travel and spatial patterns, and different behavioral activity budgets than monkeys in larger fragments and continuous forest. There was little overlap in diet between bearded saki groups, even when fruiting species were present in several study sites. The lack of successful births in the small forest fragments, discrepancies in diet between groups, avoidance of low-growth matrix, and avoidance of particular habitats raise concern for the population's future. Forest fragment size and habitat type, as well as the presence and configuration of forest patches and secondary forest growth in the matrix, are important considerations when managing arboreal primate species in a fragmented landscape.