INTERVENTIONS AND ALLIANCE FORMATION BETWEEN FEMALE JAPANESE MACAQUES, MACACA-FUSCATA, DURING HOMOSEXUAL CONSORTSHIPS

The purposes of this study were to assess whether homosexual behaviour promotes alliance formation between sexual partners and whether indiv iduals engage in homosexual behaviour to form alliances. Data were col lected during pre- and post-consortship baseline periods and during 21 of 28 different homosexual consortships observed ad libitum. These co nsortships involved 14 female Japanese macaques, Macaca fuscata, livin g in a captive, bisexual group of 37 individuals. Non-kin females inte rvened for each other significantly more when in homosexual consortshi ps than during the baseline periods. Consort partners did not interven e for other sexually mature, non-kin females in this manner. Intervent ions were not performed as sexual solicitations. Subordinate consort p artners were equally likely to receive alliance support against domina nt and subordinate targets, and they routinely received support agains t targets with whom they had ambiguous dominance relationships. Compar ed to the baseline periods, subordinate partners directed more agonist ic behaviour to other group members, who, in turn, avoided agonistic i nteractions with these females. Some consorting females, especially su bordinate partners, temporarily increased in dominance upon receiving support against dominant targets, or targets with whom they shared an ambiguous dominance relationship. Absence of preference for high-ranki ng consort partners, coupled with the bi-directional flow of most affi liation within consortships, suggested that choice of same-sex partner s was principally based on mutual sexual attraction and not on their p otential utility as allies. These data suggest that homosexual behavio ur promotes alliance formation between sexual partners, but that indiv iduals do not engage in homosexual behaviour for the express purpose o f forming alliances. (C) 1996 The Association for the Study of Animal Behaviour