Socioecological context of parturition in wild Japanese macaques (Macaca fuscata) on Yakushima Island

Female primates may adopt special feeding, foraging and social strategies around the time of giving bir-th. We observed 8 females during the prepartum period, the day of birth, and the postpartum period in a wild troop of Japanese macaques (Macaca fuscata yakui) on Yakushima Island Japan. We collected data on their activity budgets, quantitative feeding find foraging behavior, and on female-male interactions. On the day of birth, females spent less time moving and feeding, and more time resting relative to other periods. Overall dietary diversity as well as arthropod foraging also decreased on the day of birth. Females feet mostly on mature leaves, new leaves and shoots during prepartum periods brit mostly on fruit during postpartum periods. Decreased feeding on leaves and increased feeding on fruit probably changed as a result of seasonal availability, independently of parturition. Feeding on flowers; fungi and other items remained constant over all peripartutitional periods. On the day of birth, new mothers had fewer social interactions with males and spent more time out of proximity with other adults than in other periods. Females rejected grooming presentations from males, groomed less with males, spent less time less than or equal to 3 m of males, and received Less aggression from males on the day of birth. In the postpartum period interactions with males returned to prepartum values. Grooming with females did not differ across the three periods. These results suggest that inter-actions with males may be costly for females on the day of birth.