金華山島のニホンザル野生群で観察されたオトナメスの長期群れ離脱と再合流

抄録

Female emigration in Japanese macaques is thought to be atypical. However, rare cases have been recorded at several study sites. Here, I report a case in which an adult female (Nao, 19 years old) from Kinkazan Island separated from her troop for one and a half months before rejoining it. Why the female separated from her troop remains unclear, but she appeared to have been actively keeping away from the troop. Soon after rejoining, agonistic interactions between the female and other troop members, and between a pair of third party individuals, occurred frequently, as did embracing behavior between the female and her 7-year-old daughter. Embracing behavior might have reduced social tension caused by the rejoining event and subsequent agonistic interactions. Grooming between the returning female and 6 other adult females was recorded during 53 minutes of observation soon after her return, which might function to renew social relationships following the female's period of absence. Furthermore, these interactions reflected dominant-subordinate relationships and affiliative relationships between the returning female and other troop members before separation, with the exception that dominance rank of the returning female and her daughter might have reversed. These results suggest that social relationships among troop members persist despite the absence of any interactions for one and a half months.