ALTERNATIVE REPRODUCTIVE TACTICS AND REPRODUCTIVE SUCCESS IN MALE RHESUS MACAQUES

Male rhesus macaques on Cayo Santiago use rank-dependent alternative reproductive tactics. High-ranking males can form long-term consorts and guard female mates while low-ranking males frequently resort to quick copulations under the cover of vegetation. No single reproductive tactic provided the Group S males with a definitive reproductive advantage during the one-year study. Males using the long-term tactic and the quick, stealth tactic sired five offspring each, but fewer males used the long-term consort tactic. Males using the long-term reproductive tactic have significantly greater mating success than males using the quick, sneaky tactic, and may have greater reproductive success. The highest-ranking males who form long-term consorts had the greatest degree of reproductive success. This indicates that for the highest-ranking males, forming long-term consorts is the most effective reproductive tactic. The effectiveness of alternative tactics for high-ranking males (i.e. consort disruption and possessive following) was equivocal. Consort disruption had no immediate effect on reproductive success. Possessive following may have resulted in the siring of two offspring by the alpha male, but was ineffective in other cases; where the females were inseminated by subordinate males. The effectiveness of the quick, furtive tactic was demonstrated by the siring of 45% of the infants by males who used this tactic. Thus males who are not high-ranking and cannot form long-term consorts can reproduce. This study demonstrated that alternative reproductive tactics are used and reap reproductive benefits for males in the seasonally-breeding rhesus macaques on Cayo Santiago.