Environmental enrichment as a means of increasing male-female social interactions in a critically endangered species, Macaca nigra.

Abstract

Environmental enrichment refers to any modification of the physical and social environment of an exhibit in an attempt to improve the animal’s quality of life in captivity. While prolonged levels of both high and low stress tend to result in a suppression of reproductive physiology, acute, yet moderate stress can potentially promote reproductive activity. Sulawesi Crested Macaques are critically endangered. The species exhibits a polygynandrous (multi-male/multi-female) mating system. The captive Macaca nigra population at the Buffalo Zoo was observed for 14 weeks, alternating between an enrichment item and lack of enrichment, and interactions between males and females were recorded. Analysis indicates a significant increase in the frequency of friendly behaviors in the presence of enrichment, accounting for 90.43% of behaviors compared to 71.24% of behaviors without enrichment. A decrease in frequency of unfriendly behaviors was also observed with enrichment, in which 9.57% of behaviors were unfriendly compared to 28.76% of behaviors without enrichment. An increase in duration of grooming behavior from a mean of 154.2 seconds to 279.8 seconds with enrichment was observed. If enrichment can be used to increase social interactions between males and females, then this research has the potential to improve captive breeding programs, particularly for threatened, endangered and/or slowly reproducing species.