Effects of manipulatable objects on the activity of captive capuchin monkeys (<i>Cebus apella</i>)

Abstract

Abstract The aim of this study was to evaluate simple behavioral enrichment procedures for a captive group of tufted capuchin monkeys ( Cebus apella ). We examined the effects of providing a manipulatable substrate (straw) and a variety of portable objects in the monkeys' home cage. The animals were observed across three conditions in two replications: 1) No portable objects were present; 2) a set of six identical portable objects was present; and 3) a set of six varied portable objects was present. The cage floor was bare in the first replication; straw was uniformly spread on the cage floor in the second replication. An 18‐month period of qualitative note taking followed completion of the initial data collection phase. The presence of straw and portable objects affected patterns of affiliation by decreasing quiet contact and close proximity. Providing additional manipulative opportunities affected both the form and frequency of object‐directed activities. Object contacts were directed toward a greater variety of targets, and some objects were spontaneously used as tools. Manipulation of provided objects and use of objects as tools have become routine activities in this group of monkeys. We conclude that providing straw and portable objects in an already well equipped cage is an effective means of long‐term behavioral enrichment for captive capuchin monkeys. Enabling captive capuchins to express species‐typical manipulative tendencies is apparently conducive to the monkeys' optimal physical and psychological well‐being as well as interesting to the human observer.