Influence of Male Competition and Female Mate Choice On Male Mating Success in Barbary Macaques (Macaca Sylvanus)

Abstract

AbstractTo evaluate the importance of male competition and female mate choice for male mating success in Barbary macaques, focal female observations during the conceptional estrus were conducted in a large semifree-ranging group. Analysis of sexual behaviour included 121.7 h of observation of 19 focal females. In addition, ad libitum recorded male agonistic interactions, occurring in the vicinity of the focal females, were analyzed. Both sexes initiated sexual associations, and females were found almost always in contact (within 2 m) with a male. Most matings took place within 1 min after contact establishment, and the proportion of these quick matings was especially high for subadult males, which mainly "sneaked" copulations during moments of distraction of adult males. Mating contacts were longer than non-mating contacts, and varied in duration from a few seconds to more than 2 hours. Mating contacts with adult males did not differ in length with respect of the initiating sex. Females were considerably more active in terminating than initiating contacts. Females mated, on average, once every 30 min, and had 1-10 different partners (out of 37 sexually mature males) during a 4 h observation session. Females mated with 40-100% of their contact partners. An absence of mating with specific males was due to interference by other males, improper timing of contact, or (temporary) lack of attractivity of the female rather than related with a rejection of these males in almost all cases. Similarly, a highly significant positive correlation between mating frequency of a male and time spent in the vicinity of the focal females revealed that females did not discriminate among potential mates, and, hence, did not exercise mate choice. The majority of matings (71 %) were accumulated by 7 out of the 9 oldest males and additionally 2 young adults. One indicator for sexual competition among males was the peak of male injuries during the mating season. Aggressive interactions between adult and subadult males, indicating a clear-cut dominance of the adults, occurred frequently, while dyadic agonistic interactions between adult males were rare and inconsistent. The available data indicated age-inversed rank relations and were not predictive for mating success. A highly significant positive correlation was, however, found between male mating success and the participation as ally in polyadic agonistic interactions. The oldest males gave and received most support and were rarely victims of coalitions while the reverse was found for young adult males. All males followed an "age rule", after which the older of 2 males was supported during a conflict. Consequently, male power asymmetry in polyadic conflicts ran counter that in dyadic situations, and could change quickly depending on the presence of potential allies. Chances for dyadic solutions of conflicts were rare on the ground where most estrous females and the old males spent their time. Although females did not reject potential mates, they nevertheless influenced male mating success by inciting male competition. Females often tried to contact a new partner after a mating, thereby actively putting both males into conflict. The creation of such encounters was possible only between males with low power asymmetry, and only males which got successfully through these frequent female-initiated tests of their power had a high mating success. Incitation of male competition was discussed as a female mating tactic in species with a high sexual dimorphism. Compared with other macaques, the Barbary macaque belongs to such species.