BEHAVIORAL-EFFECTS OF ENRICHMENT ON PAIR-HOUSED JUVENILE RHESUS-MONKEYS

Among captive primates, inanimate environmental enrichment can lead to measurable changes in behavior indicative of an improvement in psycho logical well-being. Although this has been demonstrated repeatedly for singly caged primates, the relationship is not as well studied for pa ir-housed animals. Study of the pair-housed setting has become increas ingly relevant because of the social housing mandate of the Animal Wel fare Act regulations. We therefore observed 68 juvenile rhesus monkeys born in 1988 and 1989 and living in mixed-sex pairs from the ages of 2 to 3 years. All pairs were compatible. Half of the pairs received tw o types of enrichment, while the remaining pairs served as controls. E nriched and control juvenile subjects differed in the amount of time t hat they spent being inactive, playing, and drinking, but did not diff er in the amount of time they spent interacting with their partner. Gr ooming and play were the two most common socially directed activities in both groups, a species-appropriate pattern. Males played more and v ocalized less than did females. Overall, enriched and control subjects spent equivalent amounts of time located within a social distance of one another, but there was some difference between groups in allocatio n of behaviors while near the pairmate. Environmental enhancers were f requently utilized, and led to relatively small changes in behavior be tween control and enriched subjects, suggesting that the presence of a partner for juvenile rhesus monkeys acts as a form of enrichment that may dilute the effects of inanimate environmental enhancements. (C) 1 994 Wiley-Liss, Inc.