Differential effects of ambient temperature and humidity on allogrooming, self-grooming, and scratching in wild Japanese macaques.

This study presents data on the effects of variations in ambient temperature and humidity on behaviors related to the care of the pelage (allogrooming, self-grooming, and scratching) in wild Japanese macaques (Macaca fuscata yakui). The amount of time monkeys spent allogrooming was essentially unaffected by variations in ambient temperature and relative humidity. Frequency of scratching and, to a lesser extent, time spent self-grooming significantly increased when ambient temperature and/or relative humidity increased. These results are interpreted in relation to the differences in ultimate function that exist between allogrooming (with both hygienic and social functions) and self-grooming and scratching (with a solely hygienic function).