Landscape influences on the natural and artificially manipulated movements of bearded capuchin monkeys

Abstract

Cognitive mechanisms underlying the choice of movement patterns between resource sites for nonhuman primates are not well understood. Specifically, the influence of landscape features on decision making and spatial memory of naturally ranging animals has not been explicitly investigated. We evaluated three models of bearded capuchin monkey, Sapajus libidinosus, movement decisions that incorporated varying degrees of landscape and memory influences, and we conducted a field experiment using a novel call-back technique to test these influences. The movements and spatial decisions of the monkeys were modelled between temporal stop points and spatial change points during natural travel using straight-line path, a minimum-resistance path and landscape-perceiving path models. For these movement models, resistance was calculated as the inverse of habitat suitability, a surface based on the natural movement patterns of the study group. Of the three models, natural travel most closely resembled the straight-line path model in its landscape resistance, but not in its geometry. This result indicates that while the monkeys travel in zones of low resistance, they do not minimize distance or landscape resistance between travel nodes. When monkeys were called to an artificial resource site using the call-back experiment, their travel was more linear and higher in landscape resistance. The limited quantity and high quality of the food resource in the artificial resource sites may have influenced the nature of the monkeys' travel in these experiments. We present the advantages and challenges of the call-back method of experimental analysis of animal movement and we conclude that future analyses of spatial cognition should include consideration of landscape context.