Population densities and community structure of birds in broadleaved woodland in the lowveld of Swaziland

摘要

Population density and community structure of birds was studied at three sites in broadleaved (combretaceous) woodland in the lowveld of Swaziland. Birds were surveyed monthly using a standard point count technique. A total of 94 species of birds was recorded. Species richness at the three sites ranged between 57 and 73 species. Population density was similar at the three sites and ranged from 11.8 to 13.9 birds/ha. Biomass of birds was also similar at the three sites. Resident birds only accounted for 49% of all species, but made up 85% of the individuals and 82% of the biomass. There was a relatively large number of vagrant species, but they only accounted for 10% of the individuals and 14% of the biomass. Species richness of intra-African and Palaearctic migrants was low, and they contributed little to the bird density or biomass. In terms of diet, most birds were insectivorous, with mixed diet and granivorous species contributing approximately equally to biomass. Frugivorous species and raptors contributed little. The avifauna of broadleaved woodland in Swaziland is compared with that of other broadleaved woodlands in southern Africa and with that of Acacia savanna in Swaziland. Broadleaved woodland in Swaziland appears to support an avifauna which is depauperate compared to that of Acacia savanna, but not distinct from it.