1. British Trust for Ornithology, The Nunnery, Thetford, Norfolk, United Kingdom
2. FitzPatrick Institute of African Ornithology, Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
3. Centre for Functional Biodiversity, School of Life Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa
4. BirdLife South Africa, Isdell House, Johannesburg, South Africa