1. Department of Wildlife, Fish, and Environmental Studies; Swedish University of Agricultural Sciences; Umeå 901 83 Sweden
2. Department of Zoology; Centre for African Conservation Ecology; Nelson Mandela Metropolitan University; PO Box 77000 Port Elizabeth South Africa
3. Department of Biology; Centre for Ecological and Evolutionary Synthesis; University of Oslo; PO Box 1066 Blindern Oslo 0316 Norway
4. Department of Ecology and Environmental Science; Umeå University; Umeå 901 87 Sweden