FISSION OF A SPOTTED HYENA CLAN - CONSEQUENCES OF PROLONGED FEMALE ABSENTEEISM AND CAUSES OF FEMALE EMIGRATION

We describe the fission of one large East African clan of spotted hyen as (Crocuta crocuta). During an 8-mo period from late 1989 to early 19 90, 8 of 22 adult females vanished from the clan, along with their juv enile offspring. 6 of these 8 adult females formed a new clan in an ar ea adjacent to the parent clan's home range. The 6 adult female disper sers belonged to three mid- or low-ranking matrilines in the parent cl an. Two juvenile males returned to the parent clan for temporary visit s, and three female members of one matriline rejoined the parent clan after absences of over 8 mo. Returning females, but not males, were ta rgets of severe aggression by adult female residents of the parent cla n, and by juvenile residents of both sexes. Returning females fell fro m their previous mid-ranking positions to the bottom of the adult fema le hierarchy. Our data suggest that clan fission was promoted by the s imultaneous occurrence of low food availability, an unusually high den sity of higher-ranking conspecific competitors, and the availability o f neighboring vacant habitat.