Mechanisms of maternal rank 'inheritance' in the spotted hyaena, Crocuta crocuta

Maternal rank 'inheritance', the process by which juveniles attain position s in the dominance hierarchy adjacent to those of their mothers, occurs in both cercopithecine primates and spotted hyaenas. Maternal rank is acquired in primates through defensive maternal interventions, coalitionary support and unprovoked aggression ('harassment') directed by adult females towards offspring of lower-ranking individuals. Genetic heritability of rank-relat ed traits plays a negligible role in primate rank acquisition. Because the social lives of Crocuta and cercopithecine primates share many common featu res, we examined whether the same mechanisms might operate in both taxa to promote maternal rank 'inheritance'. We observed a large dan of free-living spotted hyaenas in Kenya to test predictions of four mechanistic hypothese s. Hyaena rank acquisition did not appear to be directly affected by geneti c heritability. Unprovoked aggression from adult female hyaenas was nor dir ected preferentially towards low-ranking cubs. However, high-ranking mother s intervened on behalf of their cubs more frequently and more effectively t han low-ranking mothers. Maternal interventions and supportive coalitions a ppeared to reinforce aggression directed at 'appropriate' conspecific targe ts, whereas coalitionary aggression directed at cubs apparently functioned to extinguish their aggressive behaviour towards 'inappropriate' targets. Y oung hyaenas and primates thus appear to 'inherit' their mothers' ranks by strikingly similar mechanisms. (C) 2000 The Association for the Study of An imal Behaviour.