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


Steven Chown, Department of Zoology and Entomology, University of Pretoria, Pretoria 0002, South Africa. Tel.: +2712 420 3236. Fax: +2712 362 5242.


Aim  To examine biogeographical affiliations, habitat-associated heterogeneity 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 southern 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. Vegetation 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. Biogeographical comparisons were based on species presence/absence data and clustering techniques.

Results  Bird assemblages differed significantly between habitats both within a given reserve and between reserves, and also between reserves for a given habitat. Differences in vegetation structure contributed substantially to differences between the avian assemblages. Of the four species endemic to the MC, three (Neergaard’s sunbird, Rudd’s apalis, and Woodward’s batis) were consistently present in sand forest. The fourth (pink-throated twinspot) preferred mixed woodland. None of these endemic species was classed as rare. In the biogeographical analysis, both the sand forest and the mixed woodland bird assemblages were most similar to bird assemblages found in the forest biome or the Afromontane forest biome, depending on the biome classification used.

Main conclusions  The close affinities of sand forest and mixed woodland assemblages to those of the forest biome are most likely due to similarities in vegetation structure of these forests. Bird assemblages differ between the sand forest and mixed woodland habitats both within a given reserve and between reserves, and also between reserves for a given habitat. These differences extend to species endemic to the MC. Thus, conservation of sand forest habitat in a variety of areas is necessary to ensure the long-term persistence of the biota.