Analysis of Grooming Relationships in a Free-ranging Group of Japanese Macaques (Macaca fuscata)

Abstract

This study was conducted on a free-ranging group of Japanese macaques (Macaca fuscata) at Katsuyama, Okayama Prefecture for 52 days during the period from June 1977 through June 1978. A total of 119 animals over the age of three years were observed and a total of 2, 467 bouts of groomings were collected.Of all the grooming bouts observed, 1, 561 (63. 3%) were between relatives. Of all the grooming between relatives, slightly less than 80% of groomings were performed between mothers and daughters. In both mating and non-mating seasons, groomings occurred predominantly between females. But in the mating season, the occurrences of cross-genealogical groomings between females decreased from 35. 8% to 12. 8% of all the grooming (Table 1).In cross-genealogical grooming between females, animals tended to groom dominant ones (73. 1%) more often than they did subordinate ones (26. 9%) (Fig. 1). Analysis of grooming relationships between non-genealogical females according to age differences indicated that occurrences of grooming declined with increasing age differences (Fig. 3).With respect to the characteristic of each genealogy in grooming relationships, animals in lower-ranking genealogies had grooming relationships predominantly with animals in their own genealogy. Proportion of groomings done by animals in lower-ranking genealogies declined with decreasing dominance ranking of genealogy. Grooming relationships between central males and females were maily determined by the leader-follower relationships rather than by the dominance relationships (Tables 2 and 3).These results illustrate that groomings performed between relatives differ from those performed between non-genealogical animals with respect to primary function of grooming, and that cross-genealogical groomings play an important role in integrating animals separated by kinship into a group.