Abstract and Summary
The mating system of wild brown capuchin monkeys, Cebus apella, was studied during four years in Peruvian rainforest. The most striking feature of estrus is active continuous solicitation of males by females. During the first three to four days, the female continuously follows the dominant male of the group, approaching him with grimaces, distinctive vocalizations, and submissive-like postures. Although the female frequently attempts to initiate copulations by touching the male and running away, he rarely copulates with her more than once a day. On the next to last day of estrus, the female no longer follows the dominant male closely, and begins to solicit copulations from subordinate males. The dominant male then begins following the female and aggressively preventing other males from approaching her; during the remainder of the estrous period, male-male aggression is infrequent compared to other polygamous primates. After another half a day, the dominant male stops following the estrous female, who then rapidly solicits and copulates with up to six subordinate males in a single day. Estrous behaviors disappear after 5 to 6 days.
The frequency and intensity of female pre- and post-copulatory behaviors are significantly greater with dominant than subordinate males. Copulation duration is significantly longer in dominant males than subordinates. The dominant male has a greater frequency of copulation than any subordinate male and furthermore may have almost exclusive access to the female during the most probable days of ovulation.
The strong active solicitation by the female of the dominant male may be explained by direct benefits that she or her offspring might receive from him. Because the dominant male controls access to many food sources during periods when food is scarce, his tolerance of a particular female or her offspring could be an important component of fitness for them. It may be possible to extend this correlation between ecology and mating system to other primate species.