Comparing the Prevalence of Stereotypic Behaviors and Enrichment Use in Rhesus (Macaca mulatta) and Japanese Macaques (M. fuscata)

Abstract

To improve captive nonhuman primates’ welfare, particularly those utilized in biomedical and behavioral research, it’s important to understand their behavior. Rhesus (Macaca mulatta) and Japanese macaques (M. fuscata) are two closely related species that are commonly utilized in biomedical and behavioral research. In this study, I compared the frequency of stereotypic behaviors, which are abnormal repetitive behaviors that are apparently non-functional, and enrichment use among four groups of each species. Stereotypic behaviors were divided into motor, which the animal performed while active, and self-directed stereotypies, which the animal performed towards themselves. Enrichment use was divided into structural, which were items that were attached to the enclosure structure, and toy enrichment items, which were temporary items that were not attached to the enclosure. Groups of both species performed varying amounts of motor and self-directed stereotypies. Rhesus macaques performed significantly more motor stereotypies, p \u3c 0.05, than Japanese macaques did, but there was no significant difference in the frequency of self-directed stereotypies. Regarding enrichment use, only rhesus macaque groups received pools, which were considered toy enrichment items, if temperatures were or were expected to be ≥ 85°F. Japanese macaques interacted with enrichment items significantly less when compared to rhesus non-pool conditions, p \u3c 0.05, and pool conditions, p \u3c 0.001. When pools were present, rhesus macaques interacted with toy enrichment items significantly more, p \u3c 0.001, than did Japanese macaques. In comparing rhesus macaques in pool and non-pool conditions, rhesus macaques interacted with toy enrichment items more and were more visible in their outdoor enclosures when pools were present. These results indicate that there are behavioral differences between closely related species, but other factors such as group dynamics and individuals’ behavior may impact the frequency of these behaviors. These results also suggest that pools can be utilized as effective forms of enrichment for rhesus macaques. Species differences, individual differences, and group dynamics should be considered when applying appropriate behavioral management