Distribution and Numbers of Arboreal Birds between the Hyper-Arid Sahara and the Hyper-Humid Guinea Forests

This study quantifies the spatial variation in density of 50 arboreal bird species (17 insectivorous Afro-Palearctic migrants and 33 Afro-tropical residents: 20 insectivores, 7 frugivores 6 sunbirds) transition zone between arid Sahara humid Guinea zone, measured during dry season 2011–2019. The distribution was related to annual rainfall, with found mainly relatively residents more zone. As woody cover increases from are by default open habitats than effect largely dissolves when corrected for rainfall. data – pertaining absolute counts stratified random sites were used estimate total number birds this region. To assess reliability these estimations, population sizes calculated separately per on half-split data. two estimates deviated about 10% averages full set. Among (1322 million), most abundant (547 followed (326 nectarivorous (272 million) frugivorous (177 million). numerous Tawny-flanked Prinia subflava (128 Green-backed Camaroptera brachyura (103 migrants, three Subalpine Warbler Curruca iberiae + subalpina cantillans (62 Lesser Whitethroat curruca (48 Western Bonelli's Phylloscopus bonelli (30