Natural wetlands, which are home to many waterbirds, face an unprecedented rate of loss and degradation in Ethiopia. Nevertheless, the number of artificial wetlands associated with reservoirs that are constructed for irrigation and household water consumption purposes has increased in the past four decades. It can be argued that these reservoirs can play an important role for waterbird conservation. However, there is little information on the avian fauna of these limnetic ecosystems. The objective of this study was to assess the richness and distribution of aquatic bird species in reservoirs in Tigray National Regional State, Northern Ethiopia. Eighty-five bird species from 54 genera, 25 families, and 15 bird orders were recorded, with a mean species richness 14.23 ± 6.72 (mean ± standard deviation) per reservoir. Five of these species are near threatened, while two other species fall under critically endangered and vulnerable conservation status designations, respectively. Bird species richness was positively correlated with the surface area of reservoirs. The result provides an important insight into the ecological relationship between waterbird species richness and the limnological characteristics of reservoirs, and plays a role towards strengthening our knowledge of aquatic bird ecology and the natural history of African-Eurasian Migratory waterbirds.