Reorganization of female dominance relations after group fission of Japanese macaques (Macaca fuscata) in Arashiyama based on Kawamura's principles.

In 1986, Japanese macaques of the Arashiyama B group fissioned, with high-ranking females forming the dominant E group and the middle- and low-ranking females forming the subordinate F group (Suzuki et al. in Primates 64:79-90. https://doi.org/10.1007/s10329-022-01024-x , 2023). In 1988, we recorded the dominant-subordinate interactions among adult females in both groups and analyzed them to clarify how they reorganized their dominance relations. The two groups showed contrasting results. Two years after group fission, the past dominance relations among female kin-groups had been largely maintained in E group, whereas the dominance relations among females in F group had been significantly reorganized, with the females from some kin-groups dispersing into various rank positions within the group. In both the E and F groups, the kin-related dyads within the 2nd degree of maternal relatedness (consanguinity) (r ≥ 0.25) tended to follow Kawamura's principles (Kawamura in Primates 1:149-156, 1958), but a considerable number of dyads did not. Such deviations from the principles seemed to derive from multiple factors: past rank reversals between the mothers and daughters, social influences from high-ranking males, and changes in the membership of kin-related females following group fission; for example, disappearances of or separations from mothers. Once rank changes were fixed, however, the relations of the newly emerged mother-daughter and sister dyads again reflected Kawamura's principles.