Social Relationships and Intergroup Transfer of Young Adult Male Japanese Macaques Pre- and Post-Fission of the Katsuyama A Group

Abstract

The social relationships of 10 young adult males in a free-ranging group of Japanese macaques at Katsuyama, Okayama Prefecture, were examined pre- and post-fission. Before group fission, higher-ranking young adult males interacted less frequently with not only their mothers, but also with other matrilineally-related females than did lower-ranking males. Six-year-old males clearly formed two subgroups according to their relative rank, even though they did not form any clear subgroups at the age of two.Higher-ranking males spent more time away from females of the group than did lower-ranking males. However, when it was time for artificial feeding, higher-ranking males obtained scattered food more frequently than lower-ranking males. After group fission, four of the five higher-ranking males and one of the five lower-ranking males remained in the main group, while three of the five lower-ranking males were in the fission group.These differences in the social relationships of young adult males might reflect the female subgroups which appeared prior to group fission.