1. Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
2. FitzPatrick Institute of African Ornithology, Department of Science and Technology–National Research Foundation (DST-NRF) Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa.
3. The Ratel Trust, Niassa Carnivore Project, Private Bag X18, Rondebosch 7701, South Africa.