Behavioral adjustments and support use of François' langur in limestone habitat in Fusui, China: Implications for behavioral thermoregulation

Climatic factors such as temperature and humidity vary seasonally in primate habitats; thus, behavioral adjustments and microhabitat selection by primate species have been interpreted as behavioral adaptations. Francois' langur (Trachypithecus francoisi), a native species to southwest China and northern Vietnam, inhabits a limestone habitat with extreme climatic conditions. To understand the potential effects of climatic seasonality on this species, we collected data on the individual behavioral budgets in a T. francoisi group between January and December 2010 in Fusui County, China. Monthly, we performed 5-11 days of observation during this period, using focal animal sampling and continuous recording methods. We also recorded ambient temperature (Ta) and relative humidity (Hr) data at our study site. Results indicated that Ta and Hr were significantly correlated with each other and fluctuated dramatically on a daily, monthly, and seasonal basis. The amount of time spent resting, grooming, basking, and huddling also varied on a daily, monthly, and seasonal basis. The proportion of resting time and total sedentary activity time significantly increased at high and low Tas, respectively. The total sedentary time, resting time, and plant branch use all showed positive significant correlations with Ta. Our results suggest that behavioral adjustment and support use of T. francoisi, at least partly, were related to thermoregulation. T. francoisi minimized thermal stress through behavioral adjustments and support use. It is an adaptive behavior associated with the climatic extremes of limestone habitat. This study can potentially advise conservation management strategies in this specific habitat. Conservation efforts should focus on vegetation restoration in langurs' habitat, including those in the foothills.