Acquisition of matrilineal rank in captive spotted hyaenas: emergence of a natural social system in peer-reared animals and their offspring

Abstract

Spotted hyaenas, Crocuta crocuta, live in clans characterized by a matrilineal social system, with female dominance over males. As part of an ongoing study of the development of hyaena social behaviour, the ‘de novo’ emergence of a natural social system was documented in captive groups of peer-reared hyaenas that had not acquired their mother's rank prior to removal to a captive situation. The acquisition of rank in their descendants was examined. Dominance relationships were studied in six breeding groups using competitive feeding tests administered in different social contexts. Founding members of these groups had been collected in Africa as infants (<2 months of age) and reared in peer groups from the time of collection. Although female dominance was not evident in groups of peer-reared animals prior to sexual maturity, a natural matrilineal social system emerged in groups of peer-reared animals with their offspring. Juvenile hyaenas acquired ranks adjacent to those of their mothers, dominating much larger adults that were lower in rank that the juveniles' mothers, including the adult males. Group dominance relationships persisted during competitive tests with mothers removed, or with all adults removed, and during dyadic tests. Despite differences in group composition and in the social experience of mothers, a matrilineal social organization clealy emerged in the captive breeding groups of spotted hyaenas and their cubs. The acquisition of matrilineal rank among the offspring of peer-reared hyaenas, as well as among the offspring reared with mothers who had themselves acquired matrilineal rank as juveniles, suggests that matrilineal rank acquisition may be an inherent outcome of relationships generated between mother-offspring units and other group members, independent of a mother's degree of experience in a matrilineal social environment.