Biogeography and ecology of African waterbirds
Patterns of distribution and diversity for African waterbirds are investigated at the continental, sub-continental, ecosystem and species levels. The focal species is the Great White Pelican Pelecanus onocrotalus, one of South Africa's 'Red Data' bird species. The 'focal' ecosystem is Rondevlei Bird Sanctuary (34°'04'S, 18°30'E), one of the few conserved areas in Africa set aside especially for waterbirds. Biogeographically, waterbirds partition Africa much more coarsely (into 8 vs 18 avifaunal zones) than do non-aquatic birds. Waterbird species diversity (number of species) and endemism are higher outside the tropics, and exhibit longitudinal gradients, with higher diversity in the east. Non-aquatic bird diversity is higher in the tropics and varies latitudinally. Spatia-temporal variation in habitat availability and quality are the primary factors which control waterbird distribution, and the dynamic nature of waterbird dispersion is an adaptation to dramatically fluctuating habitats. About 69% o£ the variance in African waterbird species diversity can be explained in terms of present-day environmental variation. Part of the unexplained variance is attributed to the effects of historical factors, with areas of unexpectedly high species possibly acting as refugia during dry climatic phases.
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Percy FitzPatrick Institute of African Ornithology