Social interactions among a mother, an adopted infant, and a real infant of Japanese macaques in the Arashiyama F group

Abstract

Social interactions among a mother, an adopted infant, and a real infant were studied in Japanese macaques (Macaca fuscata) during 5-9 months of t he infants' life, compared with mother-single infant interactions. In 1987, one multiparous female in a provisioned group adopted a non-related male baby, one day after her birth of a male baby. The mother took care of the adopted infant in the same way with her real infant. Nipple contact of each infant was synchronized. When both infants were in nipple contact, the mother less frequently rejected it and less frequently left the infants, and the infants also less frequently left the mother, than they did so when either infant was in nipple contact. This indicates that the mother nursed both infants at a time, to reduce the total nipple contact time, and to increase other activities such as feeding and social interactions with other individuals. The infants might contribute the synchrony, to increase their own nipple contact time, in accordance with such tactics of the mother. This shows one case that Japanese macaques have the potential ability to modify their behavior pattern in a certain social environment.