Body Temperature and Thermal Environment in a Generalized Arboreal Anthropoid, Wild Mantled Howling Monkeys (Alouatta palliata)

摘要

Free-ranging primates are confronted with the challenge of maintaining an optimal range of body temperatures within a thermally dynamic environment that changes daily, seasonally, and annually. While many laboratory studies have been conducted on primate thermoregulation, we know comparatively little about the thermal pressures primates face in their natural, evolutionarily relevant environment. Such knowledge is critical to understanding the evolution of thermal adaptations in primates and for comparative evaluation of humans’ unique thermal adaptations. We examined temperature and thermal environment in freeranging, mantled howling monkeys (Alouatta palliata) in a tropical dry forest in Guanacaste, Costa Rica. We recorded subcutaneous (T_(sc)) and near-animal ambient temperatures (T_a) from 11 animals over 1586.5 sample hours during wet and dry seasons. Howlers displayed considerable variation in T_(sc), which was largely attributable to circadian effects. Despite significant seasonal changes in the ambient thermal environment, howlers showed relatively little evidence for seasonal changes in T_(sc). Howlers experienced warm thermal conditions which led to body cooling relative to the environment, and plateaus in T_(sc) at increasingly warm T_a. They also frequently faced cool thermal conditions (T_a