Cage toys reduce abnormal behavior in individually housed pigtail macaques

As part of a behavioral intervention program that identifies and treats individual nonhuman primates exhibiting abnormal behavior, five individually housed pigtail macaques (Macaca nemestrina) were provided with multiple cage toys in an effort to reduce high levels of abnormal behavior. Ten 30-min observations of each subject were conducted during the baseline condition and again after novel toys were presented, both loose inside the cage and attached to the outside of the cage. The new toys were used during 27% of the observation time. Kong Toys were used most consistently by the macaques during the 5-week observation period. Significant decreases in abnormal behavior and cage-directed behavior, as well as significantly increased enrichment use, were evident after the toys were added. Several of the toys were destroyed quickly, and individual differences were evident in the levels of enrichment use and abnormal behavior. Providing multiple manipulable toys as enrichment for pigtail macaques was effective in reducing abnormal behavior and was an important part of an environmental enrichment program for monkeys who could not be housed socially.