Diurnal variation of common behaviors of pigtail monkeys (Macaca nemestrina)

Diurnal variation of eight common behaviors was studied in a social group of pigtail macaques (Macaca nemestrina). In agreement with previous work, all behaviors showed marked variation throughout the day, and differences between day and night levels were significant for most behaviors. Several significant inter-behavior correlations were found which suggested that common factors were major determinants of groups of behaviors. Significant correlations between separate diurnal cycles of sleep, grooming, and general activity demonstrated that these behaviors were among the most consistent with respect to diurnal cycles. The results point to the usefulness of diurnal studies in planning primate research designs, e.g., in controlling for variables associated with diurnal cycles.