Mating and Reproductive Success in Free-Ranging Stump-Tailed Macaques: Effectiveness of Male–Male Coalition Formation as a Reproductive Strategy

Male coalition-like formation, recently found in stump-tailed macaques ( Macaca arctoides ), occurs when several top-ranking males collaboratively guard females to prevent mating with other rival and actively share secured opportunities their allies. We lack a comprehensive understanding of the proximate mechanisms underlying such male coalitions, e.g., effect genetic relatedness. Such cooperative partner choice among is particularly interesting animals, as M. , that live matrilineal (female philopatry/male dispersal) society. Theoretically, social system, females, not males, are often related each by kinship. Thus, occurrence behavior between generally common, but it would be rare unrelated/non-kin Herein, for first time, we report detailed copulatory behaviors, including reproductive success, relation formation free-ranging following direct behavioral observation analysis. coalition-forming male–male alliances occur both individuals highly those less related. identified two groups different strategies, i.e., single-male monopoly coalition-male groups. In groups, nearly 80% copulations were monopolized single or coalition males. However, strategy allows opportunistic/sneaky relatively high probability. degree success did reflect success. contrast, employing successfully shared largest group. Compared copulated considerably more number suggesting can effectively against copulation also regardless kinship/relatedness, indicating complexity flexibility inherent bond .