1. Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa
2. Scientific Services, Kruger National Park, Private Bag X402, Skukuza 1350, South Africa
3. Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
4. Northern Cape Nature Conservation Services, Private Bag X6102, Kimberley 8300, South Africa