[1] Forestry Res Inst Ghana, Kumasi, Ghana
[2] Kwame Nkrumah Univ Sci & Technol, Fac Renewable Nat Resources, Dept Wildlife & Range Management, Kumasi, Ghana
[3] Royal Soc Protect Birds, Across River Project, Kenema, Sierra Leone
[4] Univ Reading, Ctr Agri Environm Res, Reading RG6 6AR, Berks, England
[5] Humboldt Univ, Leibniz Inst Res Evolut & Biodivers, Museum Nat Kunde, D-10115 Berlin, Germany