Use of Landmark Cues to Locate Feeding Sites in Wild Capuchin Monkeys (Cebus capucinus): An Experimental Field Study

Abstract

Studies on spatial cognition in primates and other animals indicate that landmarks serve as reference points, and may be encoded as distance and/or direction vectors in navigating to concealed or out-of-sight goals (dens, nests, feeding sites). In the present research, we conducted an experimental field study of spatial cognition and foraging strategies in a group of 15 wild white-faced capuchins (C. capucinus) in northeastern Costa Rica (10°26′N, 83°47′W). Specifically, we examined the ability of wild capuchins to use the geometric relationships of an array of two and three landmark cues to predict the location of baited feeding sites. The research design involved the construction of eight visually identical feeding platforms arranged in a circle with a diameter of 8 m. We then conducted a series of six experiments in which the relative spatial positions of experimentally manipulated landmarks (yellow- and pink-colored poles measuring 2 m in height) were the only information available to the forager to efficiently distinguish the location of reward and sham feeding sites. Our results indicate that over the course of 55 consecutive days and 227 experimental trials, the capuchins visited the feeding platforms 3262 times. Group members quickly learned to attend to the spatial positions of landmark arrays and use this information to compute the location of reward platforms. In addition, given that foragers arrived at the feeding station from different directions and encountered alternative views of the landmarks, it is possible that the capuchins were able to mentally rotate the configuration of the landmark array to efficiently solve this foraging problem.