SINET: Ethiop. J. Sci., 40(2):60-73, 2017 ISSN: 0379–2897 (PRINT) © College of Natural Sciences, Addis Ababa University, 2017 ISSN: 0379–2897 _____________________ * Author to whom correspondence should be addressed. DIVERSITY, ABUNDANCE AND THREATS OF AVIAN SPECIES IN KOGA DAM AND ITS SURROUNDINGS, NORTH-WESTERN ETHIOPIA Dessalegn Taye 1 and Melaku Wale 2,* 1 Biodiveristy Institute, Bahir Dar, Ethiopia. E-mail: tayedessalegn@gmail.com 2 Bahir Dar University, P O Box 79, Ethiopia. E-mail: melakuwale@gmail.com 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. Key words/phrases: Bird species, Change of habitat, Diversity, Reservoir. INTRODUCTION Ethiopia is a country of great geographic diversity with wide altitudinal and physiographic variation. The altitude ranges from 116 meters below sea level in the Danakil Depression to the highest peak of 4,653 meters above sea level on Mount Ras Dashen. Ethiopia is rich in biodiversity and 7 thousand km 2 of its 1.1 million km 2 area is covered by water (Yilma Delelegn and Geheb, 2003). Ecosystems range from dry lowlands to humid forests, wetlands to cool highland plateaus resulting in variable climate, topography and vegetation and unique biota with high level of endemism (EWNHS, 1996). Ethiopia has established about 73 Important Bird Areas (IBAs), 30 of which comprise wetlands, while the rest represent other ecosystems (Shimelis Aynalem and Afework Bekele, 2008). Birds are considered as useful biological indicators because they ecologically adapt to all kinds of habitats (Sivaperuman and Jayson, 2006). Wetlands are important habitats of fauna (Ramseur Convention Bureau, 2000; Beury et al., 2008). However, the importance of wetlands depends on different factors (wetland size, diversity of vegetation, water quality, food resources and topography) (Mitsch and Gosselink, 2000). In wetlands, birds breed, nest and teach young, drink water, feed, rest, shelter and interact (Bibby et al., 1998). Wetlands provide food for birds such as plants, vertebrates, and invertebrates (Ramseur Convention Bureau, 2000). Birds are the most conspicuous, with specialized traits evolved to exploit the resources of habitats in rivers and wetlands (Ormerod and Tyler, 1993; Buckton and Ormerod, 2002). The effect of environmental change on the distribution, abundance and range of river birds is often reduced (Ormerod et al., 1986; Ormerod and Tyler 1993; Colombari and Cordiner, 1999; Ormerod et al., 2000).