Bird Abundance, Diversity and Habitat Preferences in the Riparian Zone of a Disturbed Wetland Ecosystem – the Kilombero Valley, Tanzania

Abstract

Wetlands provide important habitats to many bird species but are also under threat from human-caused degradation. The Kilombero Valley Floodplain Ramsar site in Tanzania has been subject to an increasing level of disturbance, but harbors the endemic Kilombero Weaver, Kilombero Cisticola and White-tailed Cisticola, as well as several other species of local, national and global importance. Using point counts over a year, we studied seasonal patterns in bird species richness, diversity and abundance, as related to habitat types in the riparian zone along the Kilombero River. Particular focus was on Important Bird and Biodiversity Area (IBA) ‘trigger’ species. Richness, abundance and diversity were highest in July, just after the wet season, and lowest in March when the water level started rising. The endemic Kilombero Weaver (Ploceus burnieri) was by far the most common species. Reeds and grass-bush habitats had the highest bird diversity throughout, and all three endemic taxa showed a preference for these vegetation types. After decades of increasing human disturbance, Kilombero still qualify as an IBA. Large numbers of livestock have recently been evicted from the area, and this study could serve as a benchmark on how this change will affect bird populations in the future.