Doctoral Dissertation Improvement: Spatial Mapping and Foraging Strategies of White-faced Capuchin Monkeys (Cebus capucinus): Insights from Natural and Experimental Field Studies

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

The goal of this research is to examine a set of behavioral and evolutionary questions concerning human and nonhuman primate cognition, spatial memory, and the ability of monkeys to form mental maps of the location and distribution of important feeding, resting, and refuge sites across a forested landscape. Primates exploit home ranges that vary on spatial scales of from less than 1 ha to several thousand hectares, and over the course of weeks and months visit and revisit hundreds of feeding sites. In the case of human evolution, selective pressures associated with the ability to navigate large distances to hunt, locate sources of raw materials for tools, and find feeding sites sufficient to feed group members is likely to have played a critical role in enhanced cognitive abilities. However, little is known concerning how nonhuman primates internally store spatial information and the degree to which individuals take direct and planned routes to sequential feeding sites. Two primary forms of spatial memory have been hypothesized for primates. It has been suggested that primates might internally represent spatial memory in the form of a geometric map in which points in the landscape are stored as true coordinates. Such a map has been described as a "view from above" in which individuals calculate precise angles and distances between targets or goals. Individuals using a geometric map should be able to calculate novel, direct short-cut routes between distant feeding sites. Alternatively, primates may internally represent spatial information as a route-based map in which individuals use and reuse a set of common pathways and a select number of landmarks, either singly or in combination, to reach a large number of targets or goals. In this study th PIs examine questions of primate cognitive ecology by studying spatial memory in wild white-faced capuchins (Cebus capucinus) in Costa Rica. Capuchins are unusual among New World primates in that they are reported to exhibit a set of behaviors reminiscent of early human ancestors including the coordinated hunting of mammals and tool use (including stone tool use). Capuchins also are characterized by an enlarged brain and enhanced manipulative abilities. Therefore, they represent a relevant primate model for addressing important evolutionary questions concerning relationships between ecology, problem-solving, increased brain size, and cognitive complexity. The PIs plan to examine capuchin cognition using two research techniques. First, they will use a behavioral-ecological approach and study decision-making, travel, and movement patterns of capuchins naturally in the forest. Secondly, they will use an experimental field approach by placing feeding sites in particular locations in the forest to determine how quickly the capuchins learn the spatial location of these new feeding sites, arboreal pathways taken to reach these feeding sites, and the degree to which these routes are most consistent with a coordinate- based mental map or a route-based mental map. The scientific merit of this study is that it will add to an understanding of the challenges primates naturally face in locating resources that vary in time, space, and quantity in order to identify the set of selective pressures that may have played a critical role in the evolution of complex decision-making and enhanced cognitive and spatial abilities in humans. The broader impact of this research is that the knowledge gained will contribute to an expanding data base on social learning and cognition in wild primates. The majority of studies of learning in primates is conducted on single or small numbers of isolated individuals in a laboratory setting. However, virtually all wild primates are social foragers, and therefore have access to both social (who to follow, who to avoid, who to join) and ecological information (spatial, temporal, quantity information). How difference species use this information is poorly understood. This study will provide an important model for future studies on decision-making and learning in wild primates.