1. AP Leventis Ornithological Research Institute, University of Jos, Jos, Nigeria
2. Animal Demography Unit, Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
3. Department of Zoology, Faculty of Science, University of Lagos, Akoka, Yaba, Nigeria
4. British Trust for Ornithology, University of Stirling, Stirling, FK9 4LA, UK
5. Centre for Biological Diversity, University of St Andrews, St Andrews, Fife KY16 9TH, UK