Nature Environment and Pollution Technology

Anteneh Shimelis ¹, Ermias Addmasu ², Afework Bekele ², Stuart Williams ³, Simon Thirgood ⁴

Affiliations
1 Department of Biology, Addis Ababa University, ET
2 Addis Ababa, Semen Mazegaja, ET
3 Fauna and Flora International, Cambridge, GB
4 Macaulay Institute, Craigiebuckler, Aberdeen, AB15 8QH, GB

Abstract

The Afro-alpine moorlands of the Bale Mountains National Park (BMNP) constitute a diverse guild of avian carnivores. The response of the species richness of this guild to ecological processes is evaluated in this paper. Importance of elevation, topographic physical features, patch heterogeneity of habitat and prey were evaluated in explaining the species richness of the guild of diurnal raptors. The spatial variation in the moorland ecosystem as result of associations of these explanatory process variables was determined through a Principal Component Analysis. This showed there were three spatial clusters of census patches that held significantly different number of species of the guild. Importance of the variables that defined the spatial variability of the ecosystem in explaining the changes in the species richness of the raptor guild was explored through simple correlation analyses and step-wise multiple linear regression that made use of PCA components of covarying explanatory variables. The first axes of the PCA mainly defined by elevation, patch physical features, habitat heterogeneity, diversity of relatively small birds and relatively large sized avian and mammalian prey was selected as a significant predictor. In this model, species richness responded negatively to the environmental variables. Heterogeneity of patches in vegetation type and species richness of prey communities that included birds and mammals such as hare and hyrax affected the species richness of the raptors significantly positively. A simple linear regression model showed interspecific niche overlap declined as a function of species richness.

Keywords

Bale Mountains National Park, Raptor Guild, Species Richness, Afro-Alpine Moorlands.

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