Consequences of deforestation on bird diversity in the Hamuma forest, southwestern Ethiopia

Abstract

The Afromontane forests of Ethiopia are global biodiversity hotspots, known for their high biological diversity and endemism. However, conservation of these areas is challenging due to increasing human-induced threats. In this study, the effects of forest disturbances on birds were examined in the Hamuma Forest, an Important Bird Area, in the south-western Ethiopia. Birds were sampled across two seasons in three habitat types: intact forest, cultivated land (forest converted to settlement and cultivation), and open land (open bush land, grasslands and open woodlands). Using bird assemblage and functional traits of birds related to habitat type, the differences among the habitat types were examined in terms of avian species richness, taxonomic diversity, abundance, and assemblage composition. Bird assemblage species richness and abundance were not significantly different between the forest and cultivated land habitats, but were significantly lower in the open land habitat than the former two habitat types. Mean taxonomic diversity of bird assemblages was also significantly greater in the forest than in the cultivated land and open land, but the difference between the latter two habitat types was statistically not significant. At guild level, however, species richness and abundance of forest specialists were significantly greater in the forest habitat than the other habitat types. Assemblage composition was distinct among the habitat types and the pattern of assemblage was attributed to variations in vegetation structure among sites, mainly by tree and shrub abundances. These findings suggest the need for continued protection of intact forest ecosystems to maximize functional heterogeneity associated with specialist tropical forest taxa.