Faecal androgen concentrations in adult male spotted hyaenas, Crocuta crocuta, reflect interactions with socially dominant females

Androgens influence many physiological processes in male vertebrates and have been linked to variation in aggression and, reproductive behaviour in many species. This study examined relationships between social behaviour and androgens excreted by adult male spotted hyaenas. In this species, males rarely direct reproductive aggression towards other males, but they actively court females that are socially dominant to them. We tested,whether intersexual interactions were associated with elevated androgens in adult males. We combined behavioural data collected over 7 years from one large clan in Kenya with analysis of faecal androgens (fA) to determine which of the following were the best predictors of fA concentrations in males: social rank, tenure in the clan, courtship, association with females in particular reproductive states, reproductive aggression among males or nonreproductive aggression among males. We found no systematic influence of age or social status on fA in either adult natal or immigrant males. Concentrations of fA were greater in immigrants when they courted females than at other times, and greater fA concentrations were also associated with male-male aggression involving defence of a female but not with male-male aggression occurring in other contexts. fA concentrations in immigrants were also positively correlated with degree of association with females near the time of conception, but not with lactating females. These findings suggest that androgen concentrations in immigrant male hyaenas are more related to interactions with attractive females than to competitive male interactions. The most important challenge to adult males may be interacting with attractive females to which males are socially subordinate.