Effect of Habitat Quality on Primate Populations in Kalimantan: Gibbons and Leaf Monkeys as Case Studies

Abstract

Primate ecologists seek to answer fundamental questions about how and why particular ecological factors influence primate individuals, groups, and populations (Isbell 1991; Sterck et al. 1997; van Schaik 1983; Wrangham 1980). While primatologists have used a variety of approaches to address these questions, the study of a particular taxon across a range of ecological conditions provides a particularly useful framework for investigating key questions about the interactions between primates and their habitats (Davies 1994; Doran et al. 2002; Morrogh-Bernard et al. 2009; Strum and Western 1982; van Schaik et al. 2009). Studies conducted on small spatial scales may be especially useful in this context because they permit investigation of the effects of variation in some ecological conditions while controlling for others (e.g., Caldecott 1980; Chapman and Chapman 1999; Dunbar 1992a; Iwamoto and Dunbar 1983). While such studies may address fundamental ecological questions in ways that other research designs cannot, they remain relatively underutilized. Understandably, given the difficulties of sampling long-lived, generally rare vertebrates, most primate studies have focused on a single or small number of groups. Equally reasonably, most studies are conducted in relatively high quality habitats, where behavioral data can be most efficiently collected. The focus on a small number of groups and disproportionate sampling of high quality habitats may limit our ability to observe variation in a species’ ecology, hamper examination of the full range of behavioral plasticity that a primate species exhibits, and bias our understanding of how ecological factors affect primate populations.