Doctoral Dissertation Research: Ranging Behavior, Group Cohesiveness, and Patch Use in Chiropotes Satanas Chiropotes

Washington University, Saint Louis MO

Investigators

Abstract

The relationship between feeding competition, primate group size, and ecological conditions has been the subject of intensive study for the past two decades. Specifically, researchers have focused on the effect of the distribution and availability of food resources on grouping patterns and ranging behavior. Several species of primates rely on subgrouping to reduce feeding competition within the group, and subgroup size is thought to be highly correlated with the size of feeding patches. However, quantifying the distribution and quality of feeding resources utilized by primates has been difficult in previous studies of primate behavioral ecology. This study aims to clarify the effect of the distribution and availability of food resources on grouping patterns and ranging behavior in the brown bearded saki Chiropotes satanas chiropotes. Bearded sakis are one of several primate species that rely on subgrouping to mitigate feeding competition. These primates exhibit a number of different patterns of group fissioning across studies. Unfortunately, members of the genus Chiropotes are among the least studied neotropical primates and few long term studies have been conducted in large tracts of undisturbed, lowland rainforest. The primary objective of this research is to test hypotheses relating group fissioning patterns and ranging behavior in Chiropotes satanas chiropotes to resource distribution and availability using Geographic Information Systems (GIS). GIS will be used to quantify the size and quality of bearded saki feeding patches to assess the extent to which bearded sakis mitigate feeding competition through group fissioning. This research has intellectual merit in the fields of primate behavioral ecology and conservation biology. Through the use of GIS, this study will test fundamental theories of the influence of ecological variables on primate sociality with a powerful new technology. This study will be one of the first to use GIS to quantify food patch and group fissioning, and will provide a model for further studies on such relationships. In addition, this research will enhance our understanding of the relatively unstudied bearded saki in the highly interesting, yet poorly described country of Guyana. Guyana's rainforests are among the least disturbed in the world and many areas support communities of eight species of primates. The natural history data collected in this study will shed light on the ways primates respond to different ecological conditions and help refine theories of the determinants of primate sociality. Finally, this research will encourage the conservation of one of the most undisturbed regions in the tropical world.