The spotted hyena, Crocuta crocuta, is unique among mammals in exhibiting many behavioral differences between males and females that are reversed from normal mammalian sex-role patterns. Of particular interest is the observation that females are far more aggressive than males, and socially dominant to them. Drs. Holekamp and Frank will carry out a 3-year field study of behavioral development in spotted hyenas. The objectives of the research are to (1) document the emergence in infants, and maintenance in sub-adult hyenas, of behavioral differences between males and females, and (2) test several hypotheses suggesting factors promoting expression of such dimorphic behaviors as dispersal and dominance interactions. The study animals comprise one large hyena "clan" in the Masai Mara National Reserve, Kenya. Age, sex, kin relations, and social status are known for all clan members. Data collection will involve radio telemetry and four behavior-sampling protocols: scan samples, focal-animal observations, critical-incident samples, and standardized behavioral tests administered at the study site. The research will generate useful information in at least three ways: It will (1) provide comparative data on behavioral development available for no other social carnivores, (2) facilitate interpretation of data obtained in a concurrent study of behavioral endocrinology and development in captive hyenas, and (3) permit Drs. Holekamp and Frank, in conjunction with the captive study, to determine whether any of the same social, ecological, and physiological variables known to influence development of sex differences in behavior in rodents and primates also operate in this species.
