Androgen levels in the Spotted hyaena Crocuta crocuta: the influence of social factors

The Spotted hyaena is characterized by a suite of unique morphological and behavioural adaptations in the female: the external genitalia are nearly indistinguishable from those of the male, and females dominate males in most behavioural interactions. In a previous study of southern African hyaenas, males and females were found to have similar levels of circulating androgen, and it was suggested that relatively high foetal and adult levels are associated with female genital masculinization and dominance over males, respectively. This study shows that females from an East African population have androgen levels significantly lower than males, and that these levels in both sexes are strongly affected by individual social status; alpha animals had the highest androgen levels in each sex. These data cast doubt on the earlier hypothesis that aspects of sexual monomorphism in the Spotted hyaena are related solely to elevated female androgen titres.