EFFECTS OF SOCIAL AND INANIMATE ENRICHMENT ON THE BEHAVIOR OF YEARLING RHESUS-MONKEYS

Certain types of inanimate environmental enrichment have been shown to positively affect the behavior of laboratory primates, as has housing them in appropriate social conditions. While social housing is genera lly advocated as an important environmental enhancement, few studies h ave attempted to measure the influence of social conditions on the eff ects of inanimate enrichment or to compare the relative merits of soci al and inanimate enhancements. In the present study, inanimate enrichm ent (predominately physical and feeding enhancements) resulted in incr eased species-typical behavior for socially restricted subjects. Howev er, social enrichment (living in groups) appeared to be more beneficia l for young rhesus monkeys, leading to increased species-typical activ ities and decreased abnormal activities. The behavior of one cohort of yearling rhesus monkeys (Macaca mulatta) housed in small peer groups was compared with the behavior of four yearling cohorts housed in sing le cages. Half the animals in each cohort received a three-phase enric hment program and the rest served as controls. Group-housed yearlings spent significantly more time feeding and exploring and significantly less time behaving abnormally, self-grooming, and drinking than did si ngly housed yearlings. Enriched subjects spent significantly more time playing by themselves, and significantly less time self-grooming and exploring than did controls. Among group-housed subjects only, there w ere no differences between enriched and control monkeys. Captive prima tes should be housed socially, whenever appropriate, as the first and most important step in an enrichment program, with the provision of in animate enhancements being considerably less important. Limited resour ces for inanimate enrichment programs instead should be focused on tho se individuals who can not be housed socially. (C) 1996 Wiley-Liss, In c.