Behavioral processes and costs of co-existence in female spotted hyenas: a life history perspective

We assessed the importance of three behavioral processes on the fitness of individual females as mediated via maternal care in matrilineally organized social groups of spotted hyenas Crocuta crocuta. These were maternal choice of foraging tactic, the maintenance of individual dominance rank (social status) within the adult female hierarchy, and the behavioral support provided by mothers to their daughters when daughters acquired their position in the adult female hierarchy. The effects of all behavioral processes were closely linked. Maternal care was dependent on maternal social status because high ranking females had priority of access to food, and individual maternal choice of foraging tactic was frequency- and social status-dependent when medium prey abundance provided an opportunity for such a choice. At medium prey abundance, low ranking females went on costly long distance commuting trips to forage on migratory herds outside the group territory, whereas high ranking females fed on kills within the group territory. As a consequence, offspring of high ranking females grew faster, had a higher chance of survival to adulthood, and thus high ranking females had a higher lifetime reproductive success. Daughters of high ranking females usually acquired a social status immediately below that of their mother provided they enjoyed the effective support from their mothers as coalition partners, and they gave birth to their first litter at an earlier age than daughters of low ranking mothers. Spotted hyenas are therefore an example of the 'silver-spoon effect'. This study shows that the frequency- dependent outcome of behavioral processes can be a key determinant of maternal reproductive success in social carnivores and have a profound influence on the reproductive career prospects of offspring.