Bird species richness in the montane evergreen forests of the Udzungwa Mountains, Tanzania
Species richness and relative abundance of montane forest birds in the Udzungwa Mountains are presented for the 11 forests larger than 1 km2. A high positive correlation between the number of montane bird species and the size of the forest is found with the highest species richness recorded in the largest forest. A few small (< 5 km2) forest fragments also support a high richness of forest birds. Their isolation from larger forest tracts is probably relatively recent (within the last 100–200 years) and their high bird species numbers may be partly due to delayed extirpations. Twenty-three restricted range montane forest species were recorded, and many of these were widespread in the Udzungwas. The largest populations of White-winged Apalis Apalis chariessa, Dapple-throat Arcanator orostruthus, Iringa Akalat Sheppardia lowei and Usambara Weaver Ploceus nicolli are most likely in Udzungwa forests.
Keywords: Tanzania, Udzungwa Mountains, montane forest birds, distribution, abundance, extinction debt