Diversity, abundance and threats of Avian species in Koga Dam and its surroundings, north-western Ethiopia

Abstract

A survey of birds was conducted in Koga Dam Reservoir of the Amhara Region, Northwestern Ethiopia from October 2010 to March 2011. The objective of the study was to assess the diversity of birds and anthropogenic activities in the Dam and its environs. Data collection methods included transect method, interviews, and direct observations. Three habitats were identified for the study, i.e., wetland, farmland and scrubland. Diversity indices including Shannon diversity index were used for data analysis. The results showed that a total of 103 bird species belonging to 75 genera,  24 families and 11 orders were found. Charadriiformes appeared to be the most dominant order represented by 8 families and 25 species, followed by Passeriformes with 5 families and 15 species. The least was Phoenicopteriformes, Coraciiformes and Strigiformes, with1 family and 3 species each. Bird diversity was high in the scrubland (H′=3.96) and low in the farmland (H′=3.20) during the wet season. The highest species richness during both seasons was recorded in wetland (65) followed by farmland(55). The least species number was recorded in the scrubland (53). The newly constructed dam has changed the species composition and feeding habits of birds. After the construction of the dam, new bird species arrived and the number of natives increased. According to farmers, after the construction of the dam, seed feeder birds, unlike carnivores, shifted their feeding habits from the wetland to crops and became pests. Anthropogenic threats such as clearing of natural vegetation, sedimention, over-grazing, recesssion farming and over exploitation of other resources all contribute to the decline of the bird species.  Thus, appropriate measures must be taken to re-stabilize the bird habitat.