RAPID CHANGE IN OFFSPRING SEX-RATIOS AFTER CLAN FISSION IN THE SPOTTED HYENA

We describe the rapid reversal in juvenile sex ratio that occurred aft er fission of our study clan of free-living spotted hyenas (Crocuta cr ocuta). Juvenile sex ratios were strongly male biased before fission, when dan size was at or slightly above the habitat's carrying capacity (K). Clan size after fission fell below K, and juvenile sex ratios be came female biased within a single reproductive cycle. The change in j uvenile sex ratio appeared to be due to altered sex bias in cubs recru ited through births. The observed change in secondary sex ratio was on ly significant among offspring of high-ranking females. Our observatio ns were consistent with predictions of existing sex allocation theorie s based on focal resource competition and enhancement. Our data sugges t secondary sex ratios in spotted hyenas are influenced by conflicting demands of competition and cooperation among philopatric individuals.