NORMALIZING LABORATORY-REARED RHESUS MACAQUE (MACACA-MULATTA) BEHAVIOR WITH EXPOSURE TO COMPLEX OUTDOOR ENCLOSURES

In comparison with standard laboratory settings, naturalistic environments typically provide nonhuman primates with increased visual, olfactory, and auditory stimulation and greater opportunities for exploration and manipulation. Although behavioral differences between monkeys reared in the laboratory and their feral counterparts are relatively well documented, less is known about the impact of transferring laboratory-born and -reared primates to outdoor settings. Of particular relevance is whether lab-reared primates retain the ability to respond in a species-specific manner to environments designed to mimic certain features of natural habitats and if short-term transfers have beneficial consequences. The present study compared the behavior of two groups of laboratory-born juvenile rhesus monkeys reared in an identical manner. One group was then transferred to an outdoor, apparatus-enriched corncrib adjacent to a semiwooded pasture. The other group remained indoors in a standard laboratory pen. Both groups were observed for 6 weeks prior to the transfer, during the 9-week period of transfer, and for 6 weeks after the outdoor animals were returned to their laboratory cage. During their outdoor experience, corncrib-housed subjects responded with higher locomotion and exploration scores. Animals housed in the outdoor corncrib also showed a decline in self-oral behavior which persisted even upon return to the laboratory environment. These data suggest that juvenile monkeys can benefit from brief exposure to enriched outdoor settings.