Primate Cognition: Integrating Social and Ecological Information in Decision-Making

Abstract

Two major challenges that social animals face in exploiting their environment are the ability to locate ephemeral, widely scattered, and productive feeding sites and to obtain access to food resources also sought by other group members. This may include decisions concerning where to search, whom to follow, whom to avoid, an assessment of individual differences in competitive ability or dominance, and the costs and benefits of remaining in a food patch jointly occupied by others. Group foragers, therefore, are expected to solve problems of food acquisition by developing foraging strategies that integrate both social and ecological information (Giraldeau and Caraco 2000; Bicca-Marques and Garber 2005; Ottoni et al. 2005; Barrett and Henzi 2006; Bugnyar and Heinrich 2006). Virtually all species of higher primates are gregarious foragers and live in stable social groups. In some primate species, group members exploit small isolated food patches or forage in a wide or dispersed front with nearest neighbors separated by distances of 15 m to several hundred meters (Chapman and Chapman 2000). Under these conditions, individual group members act principally as searchers1, and encounter feeding sites as a result of their own search efforts (Barnard and Sibly 1981; Ranta et al. 1996; Giraldeau and Caraco 2000; Mottley and Giraldeau 2000). A searcher strategy may be associated with the concept of scramble competition (van Schaik 1989) and the advantages foragers gain through first access to a feeding site (DiBitetti and Janson 2001). Among primates that travel in a more cohesive unit or jointly exploit large and productive food patches, opportunities for information sharing may be a major benefit of social foraging, as certain group members direct their attention to the behavior of conspecifics in order