Effects of fluctuation in temperature and humidity and behavioral thermoregulation on the resting time of Alouatta palliata monkeys

Mantled howler monkeys Alouatta palliata display a daily behavior pattern, but the time they rest can vary with the use of thermal behaviors to prevent endogenous heat production, maintain body temperature, and reduce the need to consume water or energy. The primary objective of this exploratory study was to determine the effects of fluctuations in temperature and relative humidity and behavioral thermoregula¬tion (body postures and tree stratum selection) on the resting time of A. palliata introduced in Agaltepec Island, Veracruz, Mexico. Focal animal sampling was carried out between October 2018 and August 2019, collecting 384 hours of fieldwork (observation/data recording) with 628 thermal behavioral records. We used a generalized linear mixed-effects model (GLMM) to observe the possible influence of the weather variables and behavioral thermoregulation on the rest time. The results showed differences in the temperature recorded in each posture and tree strata but according to the statistical models, the adoption of postures better explained (percentage of variance: 48.21 %) the time A. palliata rests. At higher ambient temperatures and lower humidities, the monkeys adopted an ex¬tended posture in the lower tree stratum and increased their resting time. These warm conditions likely pose a significant thermoregulatory challenge for howler monkeys, promoting the use of specific thermal behaviors that may affect resting times and potentially time allocated to other behaviors, such as locomotion and feeding. These changes in their behavior could compromise their survival if the temperature continues to rise and the relative humidity decreases due to the effect of climate change. Key words: Temperature, Thermoregulation, Body postures, Arboreal stratum, Daily behavior