Behavioral thermoregulation in a group of zoo-housed colobus monkeys (Colobus guereza).

Although wild primates are known to modify behavior in response to thermal stress, less is known about behavioral thermoregulation in zoo-housed primates. Zoo exhibits expose individuals to unique thermal environments and may constrain the thermoregulatory strategies available to individual animals. In this study, we observed a group of seven colobus monkeys (Colobus guereza) living on a concrete "Monkey Island" style exhibit that featured limited shade and limited arboreal space. Behaviors were recorded using continuous focal animal sampling (n = 63 days, 97.7 hr). Logistic regression revealed 23°C was the temperature at which monkeys began resting more in shade than in sun. When temperatures exceeded 23°C, animals spent more time in open sitting postures with limbs extended from the body; sat less frequently in closed, hunched postures; spent more time in social contact; and performed more self-directed behaviors. Exhibit use also shifted under higher temperatures, with more time spent in areas with shade and lower surface temperatures. Lastly, when provided with access to an indoor holding area, the colobus monkeys spent more than half the time indoors when temperatures exceeded 23°C, yet only 10% of their time indoors when the temperature was below this value. Although postural changes have been reported in wild colobus, the postural and other behavioral changes observed in the current study occurred at temperatures lower than expected based on the published thermoneutral zone of colobus monkeys and highlight the importance of considering the specific thermoregulatory responses of zoo animals.