Fatal Attack on an Adult Female Cercopithecus mitis erythrarchus: Implications for Female Dispersal in Female-Bonded Societies

Female dispersal is uncommon among female-bonded primate societies, even though at times there may be considerable incentive to do so, e.g., to avoid potentially infanticidal males. Predation risk and the advantages of sharing the costs of group living, such as infanticide and resource defense, with close kin are assumed to limit female dispersal. However, we show that these costs may not be as important as the risks associated with integration into a new group in female-bonded societies. We report the death of a potentially dispersing solitary Samango (Cercopithecus mitis erythrarchus). She was unrelated to the females of a single group that killed her, and her death was not in the context of intergroup conflict or territorial defense. This fatal conflict is in contrast to the tolerance of female dispersal displayed by many folivorous and non-female-bonded primate species. In such non-female-bonded societies, there is less indirect fitness advantage to remaining in the natal group or to cooperate with kin to defend food patches, and consequently the risk of being rejected by another group is much reduced. Our observations show that dispersal between groups may be costly for solitary and unfamiliar females in a female-bonded society.