Preliminary analysis of the nestedness patterns of Montane forest birds of the Eastern Arc Mountains

Abstract

Previous biogeographical studies of forest avifaunal compositions of mountains in the Eastern Arc archipelago have focused primarily on patterns of species richness and the effects of montane area and isolation. This preliminary investigation examines species composition in terms of nestedness patterns for 12 mountains in this archipelago. Twenty-eight forest species (includes five species complexes), most of which are strictly confined to the Eastern Arc Mountains, were used to evaluate the hypothesis that species composition is random with respect to nestedness. Results show that the species ordering is significantly non-random. The discussion and conclusions focus on the nested subset patterns exhibited by 14 species and, to a lesser extent, 'idiosyncratic' species and islands. Factors that may have contributed to this pattern include selective extinction and colonisation; however, further work is necessary to elucidate which of these, or other factors, actually contributes to nestedness in Eastern Arc birds. Nestedness analyses serve as an important tool to predict what species may be at risk from extinction and which islands and species require greater conservation or research attention.

Journal of East African Natural History Vol. 87 (1&2) 1998: pp. 101-118