The Abbay (Blue Nile) is Ethiopia’s largest river. It originates at Lake Tana on the central plateau, leaving the lake at Bahir Dar (site ET007) and flowing for 32 km before plunging over the basalt at Tis-Isat falls. It flows through a deep, narrow gorge that runs south and east around the Choke mountains, and then turns west into the Mid-Abbay. The Mid-Abbay flows through a magnificent gorge that widens and narrows and widens again. It crosses the border into the Sudan near Bumbadi in Benshangul-Gumuz Region. The gorge effectively divides the central plateau of Ethiopia into two blocks. The Mid-Abbay river forms the boundary between Amhara and Oromiya Regions. Major rivers that feed into the Abbay are the Bir, Temcha and Beles from the north, the Didessa, Finchaa, Guder, Muger and Wenchit from the south and the Beshlo from the east. The Jemma river (site ET015) is a tributary of the Wenchit. The vegetation of the Mid-Abbay has never been well studied, but satellite photographs show extensive areas of forest and woodland. The trees in the riverine forest of the Didessa river, at c.1,300 m, comprise Ficus vallis-choudae, Mimusops kummel, Tichilia emetica, Cordia africana and Phoenix reclinata. The smaller trees include Sapium ellipticum, Dracaena steudneri and several woody climbers. It is likely that riverine forest of similar composition is found beside the Abbay river, with the addition of extensive tamarind groves and undergrowth of Ficus capreaefolia.
See Box and Table 2 for key species. No comprehensive species list exists for this area. However, Francolinus harwoodi is known to occur at a number of locations in the Mid-Abbay basin (in various places in gorges that join the river) and it may be expected to occur elsewhere in the river system in suitable scrub and thicket on hillsides. Ptilopachus petrosus is likely to occur on the rocky slopes. The Abbay river system is likely to be important for Sudan–Guinea Savanna biome species and others from the lowlands, as is the case with the Jemma and Jara valleys. For example, Cisticola troglodytes, Serinus leucopygius, Streptopelia vinacea, Sporopipes frontalis and Plocepasser superciliosus are expected to occur.
Non-bird biodiversity: An endemic cricket occurs in this area, the population of which can reach pest proportions at which point it will attack cereal crops.
BirdLife International (2020) Important Bird Areas factsheet: Mid-Abbay (Blue Nile) river basin. Downloaded from http://www.birdlife.org on 22/01/2020.