AVIS-IBIS

Birds of Indian Subcontinent

Densities of Palearctic warblers and Afrotropical species within the same guild in Sahelian West Africa

Publication Type:Journal Article
Year of Publication:2010
Authors:Wilson, JM, Cresswell, W
Journal:Ostrich
Volume:81
Issue:3
Date Published:2010
ISBN Number:0030-6525
Keywords:Acrocephalidae, Africa, Communis, Communis communis, Curruca communis, Hippolais, Hippolais pallida, Iduna, Iduna pallida, Malaconotidae, Nectariniidae, Nigeria, Ploceidae, Ploceus, Ploceus luteolus, Sylvia, Sylvia communis, Sylviidae
Abstract:Declines in populations of Palearctic migrants wintering in the Sahel of Africa have been linked to the impacts of climate change and habitat degradation in the region. Despite this, there is an almost complete lack of data on the density and distribution of Palearctic migrants wintering in the Sahel and whether they have the same habitat requirements as similar, resident Afrotropical species. We measured the density of five species of Palearctic warblers (Sylviidae) and 10 species of Afrotropical gleaning passerines (Sylviidae, Nectariniidae, Malaconotidae and Ploceidae) at 16 sites in the Sahel of northern Nigeria between October and April during two winters. Two species of Afrotropical gleaner (Hippolais pallida and Ploceus luteolus) showed seasonal variation in abundance, but this variation was unlikely to have decreased Afrotropical densities sufficiently to change the degree of competition experienced by Palearctic migrants. This observation, combined with a positive correlation between abundances of Afrotropical and Palearctic species, suggests that these two groups occur together and have similar spatial and temporal habitat requirements, and therefore possibly similar responses to habitat degradation. Sylvia communis appears to be the principal species utilising the region during spring migration, presumably for fattening prior to the trans-Saharan crossing, and is thus perhaps the most vulnerable species to habitat loss in the region.Declines in populations of Palearctic migrants wintering in the Sahel of Africa have been linked to the impacts of climate change and habitat degradation in the region. Despite this, there is an almost complete lack of data on the density and distribution of Palearctic migrants wintering in the Sahel and whether they have the same habitat requirements as similar, resident Afrotropical species. We measured the density of five species of Palearctic warblers (Sylviidae) and 10 species of Afrotropical gleaning passerines (Sylviidae, Nectariniidae, Malaconotidae and Ploceidae) at 16 sites in the Sahel of northern Nigeria between October and April during two winters. Two species of Afrotropical gleaner (Hippolais pallida and Ploceus luteolus) showed seasonal variation in abundance, but this variation was unlikely to have decreased Afrotropical densities sufficiently to change the degree of competition experienced by Palearctic migrants. This observation, combined with a positive correlation between abundances of Afrotropical and Palearctic species, suggests that these two groups occur together and have similar spatial and temporal habitat requirements, and therefore possibly similar responses to habitat degradation. Sylvia communis appears to be the principal species utilising the region during spring migration, presumably for fattening prior to the trans-Saharan crossing, and is thus perhaps the most vulnerable species to habitat loss in the region.
URL:http://www.tandfonline.com/doi/abs/10.2989/00306525.2010.519899
Short Title:Ostrich
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