Female choice and inter-sexual competition for female sexual partners in Japanese macaques

Observations of a captive colony of Japanese macaques (Macaca fuscata) were carried out with the goal of documenting (1) competition between males and females for female sexual partners and (2) choice of same-sex sexual partners by females, despite the presence of motivated, opposite-sex alternatives. Data were collected during 21 homosexual consortships involving 14 females living in a mixed-sex group of 37 individuals. Intersexual competition for female sexual partners was manifested when a sexually motivated male and female (competitors) simultaneously sought exclusive access to the same infertile or post-conception female (focus of competition). This occurred during male intrusions on female homosexual consortships and counter-challenges by female competitors against intruding males. Inter-sexual competition for female sexual partners took the form of approaches and solicitations directed at the focus of competition, as well as displacements and aggression directed at one's competitor. Females did not acquire alloparental care for their immature offspring from their same-sex consort partners. Thus, female competitors appeared to engaged in potentially risky competition for same-sex sexual partners in the absence of any obvious reproductive benefit (e.g. insemination or alloparental care). Following these Interactions, females which were foci of competition chose to mount with the female competitors significantly more often than not.