1. a Zambian Ornithological Society , PO Box 33944, Lusaka, Zambia
2. b Percy FitzPatrick Institute of African Ornithology , University of Cape Town , Private Bag X3, Rondebosch, 7701, South Africa
3. c Royal Society for the Protection of Birds , Dunedin House, 25 Ravelston Terrace, Edinburgh, EH4 3TP, UK