Spatial variation and biogeography of sand forest avian assemblages in South Africa

Aim To examine biogeographical affiliations, habitat-associated heterogenei ty and endemism of avian assemblages in sand forest patches and the savanna -like mixed woodland matrix. Location Two reserves in the Maputaland Centre of Endemism (MC) on the sout hern Mozambique Coastal Plain of northern KwaZulu-Natal, South Africa. Methods Replicated surveys were undertaken in each of the two habitat types in each reserve, providing species abundance data over a full year. Vegeta tion structure at each of the survey sites was also quantified. Differences between the bird assemblages and the extent to which vegetation structure explained these differences were assessed using multi-variate techniques. B iogeographical comparisons were based on species presence/absence data and clustering techniques. Results Bird assemblages differed significantly between habitats both withi n a given reserve and between reserves, and also between reserves for a giv en habitat. Differences in vegetation structure contributed substantially t o differences between the avian assemblages. Of the four species endemic to the MC, three (Neergaard's sunbird, Rudd's apalis, and Woodward's batis) w ere consistently present in sand forest. The fourth (pink-throated twinspot ) preferred mixed woodland. None of these endemic species was classed as ra re. In the biogeographical analysis, both the sand forest and the mixed woo dland bird assemblages were most similar to bird assemblages found in the f orest biome or the Afromontane forest biome, depending on the biome classif ication used. Main conclusions The close affinities of sand forest and mixed woodland ass emblages to those of the forest biome are most likely due to similarities i n vegetation structure of these forests. Bird assemblages differ between th e sand forest and mixed woodland habitats both within a given reserve and b etween reserves, and also between reserves for a given habitat. These diffe rences extend to species endemic to the MC. Thus, conservation of sand fore st habitat in a variety of areas is necessary to ensure the long-term persi stence of the biota.