ABSTRACT
The goal of my research was to examine the strength of the relationship between primate social behavior and ecology as predicted by socioecological models put forth in recent years (Isbell 1991; van Schaik 1989; Sterck, Watts, & van Schaik 1997; Wrangham 1980). In order to do this, I began by quantifying data on food availability for patas monkeys and vervets. At the core of each of the socioecological models lies the assumption that patterns of food availability significantly influence a primate’s behavior. Scattered, abundant, or otherwise not usurpable food resources are predicted to result in adult female-dominance hierarchies that are less stable and nonlinear, with a high percentage of rank reversals (Isbell & Pruetz 1998; Figure 2-1). If food availability has an important effect on behaviors such as intra-group dominance relations, comparing closely related species that exploit similar resources can help to establish the effects of environmental variables on social behavior and ecology. Whereas a central theory in the study of primate socioecology is that the environment and, especially, food resources within the environment influence primate social structure and behavior (Barton, Byrne, & Whiten 1996; Chapman, White, & Wrangham 1994; Crook & Gartlan 1966; Doran & McNeilage 1998; Isbell & van Vuren 1996; Nakagawa 1998; van Schaik & van Hooff 1996; Struhsaker 1969; Suzuki, Noma, & Izawa 1998; Temerin & Cant 1983; Watts 1996; White 1996; Wrangham 1986; Wrangham et al. 1996; Yeager & Kirkparrick 1998), accurate measures of the food available to primates are often lacking. Researchers have frequently relied on qualitative estimates and gross measures of food availability. Using general measures as well as the lack of standardization between studies has limited our ability to identify precise relationships between the availability of primate foods and behavior such as feeding competition. Some researchers, however, have attempted to remedy this situation by providing guidelines for between-site comparisons (see Janson & Chapman 1999; edited volume by Kuroda & Tutin 1993). In general, ecological studies of primates have been lacking in (1) accurate quantification of food availability and (2) comparability of ecological data across sites and studies. The Segera study site in Kenya allowed environment to be held constant when assessing the effects of food resources on social behavior and dominance relationships among adult females of closely related species, while providing a situation especially conducive to ecological study.
