Role of delinquent young "orphan" male elephants in high mortality of white rhinoceros in Pilanesberg National Park, South Africa

Abstract

We describe white rhinoceros (Ceratotherium simum) mortality at Pilanesberg National Park, South Africa, focussing on mortality caused by African elephant (Loxodonta africana). We reconstructed records from a range of historical sources, and estimated that up to 49 rhino were killed by elephant. There was confirmed mortality in 1994 and 1996, and based on patterns, we suggest a set of rhino mortality from elephant in 1992. Both sexes and all age classes were victims. There was no significant bias to older animals, but given the rhino population structure, there was a significant bias towards males in adult deaths. The culprits were identified as young male elephants that entered musth about 10 years younger than expected, and maintained musth for a full term at first occurrence. We attributed this to the lack of a mature bull hierarchy in the park, because these elephants were the product of translocation of young animals (<10 years old) remaining from culls in Kruger National Park. We emphasise the need for accurate monitoring and record keeping, and a focus on individual identification of key species in small reserves.