SEASONAL CHARACTERISTICS OF AVIFAUNA IN NAIROBI METROPOLITAN LANDSCAPE

Abstract

The landscape structure of Nairobi city is experiencing rapid transformation as once wild and pristine spaces are converted to anthropocentric uses. In order to understand how the changing urban structure affects urban habitats, the seasonal variation in occurrence and composition of avifauna within the metropolitan landscape of Nairobi city was investigated. The relationship between bird occurrence and spatial characteristics of surrounding urban matrix was quantified. Bird survey was conducted for two consecutive seasons in the wet and dry seasons. Landscape features within the study sites were derived from remote sensing image and used to account for bird distribution. Birds were classified according to their biological families and their naturally preferred habitat. Ordination analysis was done to find underlying correlation between species occurrence and site characteristics. About 50 different families of birds were observed between the two seasons with a total of 307 different species. Families of finches, raptors, warblers and weavers, sunbirds and thrushes were the most common. Bush and scrub habitats were most naturally preferred habitat at a rate of about 31%, followed by grassland species at about 20% and forest species at about 16% rate. Unique species recorded between the seasons constituted 22% and 17% of total observed for the dry and wet seasons respectively. The first axis of principle component analysis revealed a gradient of change from forested and woody sites to savannah vegetated sites while the second axis was change from sites with agriculture patches to sites with urban patches. The occurrence and distribution of the species was highly dependant on site use and management. As the city continues to expand, landscape and urban planners must promote urban designs that will integrate habitat conservation for healthy urban space development.