| Male social relationships, sexual behavior, endocrinology, and subgrouping patterns were examined in one group of capuchins, Cebus apella nigritus , at the Estação Biológica de Caratinga, Minas Gerais, Brazil from September 1996–August 1997. Unlike in many other tufted capuchin populations, all adult males were dominant to all adult females. High-ranking females were the alpha male's most frequent grooming and coalition partners. The alpha male was aggressive to other males, and formed coalitions with them, but showed no active affiliative behavior towards them. In contrast, subordinate adult males were never aggressive to one another, and were affiliative in both grooming and play.; Capuchin females actively solicit males for copulations, but males may delay sexual activity for hours or days. Both season and rank affected male consortship participation, sexual solicitation, mount latency, and copulation frequency. Thirty-two copulations were observed during the year. The alpha male received the most consortships, but his mating success, in terms of copulation frequency, did not differ from other adult males. In the dry season, males showed some contest competition for mates, a higher rate of alternative mating strategies, and an increase in the monitoring of female condition. No males were ever observed to mate more than once per day.; The temporal patterns in male testosterone and cortisol production were analyzed relative to female sexual activity and male-male aggression. A sustained high-magnitude increase in steroids during the dry season was associated with the peak of adult female sexual activity and a relatively low frequency of male-male aggression. The alpha male did not differ from other adult males in testosterone or cortisol concentration.; Subgrouping patterns in capuchins were compared to those in other primates. Multi-male, multi-female groups were the most common subgroup type observed. Low-ranking matrilines split off frequently from the main group, accompanied by low-ranking males. The fluidity of subgroup membership, and seasonal differences in subgroup patterns, were similar to other Cebidae species. By contrast, subgroup composition and the bimodal distribution of group size resembled Cercopithecine subgrouping patterns. |
