Orphaning and natal group dispersal are associated with social costs in female elephants

Abstract

Social environments are fundamental to fitness in many species. In disrupted societies, the loss of important partners may alter social environments for surviving individuals. African elephants, Loxodonta africana, have experienced age-selective mortality linked to the ivory trade, and the resulting social costs for surviving young elephants are unknown. In this study, we followed orphaned female elephants and nonorphaned counterparts in Kenya's Samburu and Buffalo Springs National Reserves to elucidate whether orphaning and related dispersal behaviour incur social costs. There were clear social differences between orphans and nonorphans, most notably in that orphans tended to receive more aggression than nonorphans. Dispersal from natal groups was a behaviour found exclusively among orphans. Differences in social environments of orphans that remained in their natal groups and those that dispersed were also found in the form of dispersed orphans receiving more aggression while feeding than those that remained in their natal group. Our results suggest that orphaning in elephants is associated with social costs, and that these costs are amplified for orphans that disperse from their natal groups. Future research should identify the relationship between the social costs of being an orphan and fitness, which may be important to the recovery of populations affected by the ivory trade and other forms of disruption.