A study was conducted on the diversity, relative abundance and habitat association of birds in Dek island of Lake Tanafrom August 2022 to January 2023 E.C comprising both the wet (August to October) and dry (November and January) seasons. Based on the vegetation composition, the study area comprised three habitat types: forest, modified and lakeshore habitats. The data collection was performed by using point count and line transects methods. The bird survey was conducted for a total of six months (seven days per month) 42 days with a total of 252 hours. A total of 4366 individuals of 95 bird species belonged to 39 families in 16 orders was recorded during the entire study in all habitats of the study area. The highest species diversity (H’ = 3.18) of birds was recorded in Lakeshore habitat during the dry season, while the lowest species diversity (H’ = 2.62) of birds was recorded in the forest habitat. The highest species evenness (J = 0.818) and the lowest evenness index (J= 0.743) of birds was observed in the forest habitat during the dry and wet season, respectively. The diversity of bird species was higher (H’ = 3.64) during the dry season compared to the wet (H’ = 3.61) season. The maximum species similarity (SI = 0.644) of birds was observed between the forest and modified habitats during the wet seasons. While the lowest species similarity (SI = 0.42) was recorded between the forest and lakeshore habitats during the wet season. More than 58 species of birds were recorded in lakeshore habitat. The highest abundance (1167) of birds was recorded in modified habitat during the dry seasons. Overall, the highest species of birds existed as “uncommon” category in the study area during the entire study. While no bird species occurred as the “abundant” categories. As the present data indicates, the study area harbors more diversify bird species though the area is highly disturbed due to human activities, thus the area needs priority for conserving the birds and their habitats. This preliminary study on the birds in the island will help to understand the potential impact of reduction of forest and lakeshore wetlands in the decline of diversity of avian species in the area.