Avian diversity is among the key components of the earth’s biodiversity that serve as unique barometers for environmental change. Bird diversity in unprotected habitats such as reservoirs in the Tigray region is less known. A study was conducted to assess the avian diversity in highland reservoirs of the Tigray region, particularly at Maygundi and Maysye reservoirs and their adjoining habitats from August 2022 to March 2023, covering both wet and dry seasons. A line transect and point count methods aided by binoculars were used to estimate avian species diversity and distribution. Biodiversity indices and Two-way ANOVA were used to analyze the data. A total of 1,813 individual birds belonging to 151 species, 17 orders and 51 families were recorded during the study period. Egyptian goose was the most abundant species (19.58 %), followed by Little Grebe (10. 86 %), Eurasian Coot (7.00 %), Ruff and Yellow Mantle Widowbird (3.31 % for each). A significant variation in the number of bird species between wet and dry seasons (F = 1225, df = 1, P = 0.02) and between reservoirs (F = 484, df = 1, P = 0.03) was observed. However, there was no significant difference in abundance of birds between wet and dry seasons in both reservoirs (P > 0.05). Maysye reservoir had high bird species diversity (H′ = 3.66), while Maygundi reservoir had the lowest (H′ = 3.24). The study shows that sedimentation and habitat destruction due to anthropogenic activities, including the expansion of settlements; agriculture and livestock grazing were the main threats to bird diversity. The highland reservoirs and their adjoining habitats support high avian species diversity including endemic and endangered species revealing the importance of the sites for bird conservation. Therefore, urgent conservation measures are recommended for long-term bird conservation.