Lake Tana is in the north-west corner of the Ethiopian plateau, c.350 km north-west of Addis Ababa. The Lake is the largest in Ethiopia, being c.68 km wide and 73 km long, but only a maximum of 14 m deep. There are 37 islands in the Lake, many of them sites for ancient churches and monasteries, others supporting large colonies of birds. Bahir Dar, the capital of Amhara Region, is on the southern shore of the lake where the Abbay (Blue Nile) river flows out. The Lake Tana basin has a catchment of 150,000 km². It is fed by over 60 rivers (the major ones are the Gilgel Abbay, Megech, Gumara and Rib) and streams flowing from the Simen mountains to the north, the large central plateau to the east and the gentler sloping land to the west. The variation in annual water-level is c.1.6 m. The major habitats around Lake Tana are farmland, grassland, forest, rocky areas, marsh, reedbeds and the lake itself. Water retention is high, making the area prone to inundation. The Bahir Dar area is particularly well known for oil crops and Carthamus tinctorius. The flat land, particularly where water lies in the rainy season, is grassland with a mixture of palatable indigenous grasses and legumes. The marshes support a variety of grasses, sedges and climbers. The mixed forests comprise figs, Syzygium guineense, Cordia africana, Albizia spp., Prunus africana and the endemic Millettia ferruginea as common trees, a well-developed shrub layer and woody climbers. Huge figs, Ficus vasta, are also found as isolated trees in farmland and on the lake shore. The Zege peninsula is home to a distinctive coffee variety that grows in the shade of Acacia and Millettia ferruginea trees. One of the most striking features of Lake Tana is the extensive Papyrus beds from which the local boats, ‘tankwa’, are made. Other large plants in the reedbeds are Typha, Echinochloa spp. grasses and Polygonum. Several aquatic plants, including Nymphaea coerulea, are noticeable. Fortunately, the invasive Eichhornia crassipes is not present. The human population of Bahir Dar is growing quickly as the city develops, now having two institutes of tertiary education and a large school-age population. Farming and fishing are the most common occupations outside the town and there are many priests, monks and nuns associated with the churches around the lake and on several of the larger islands.
See Box and Table 3 for key species. This site is particularly important for waterbirds, some of which occur in large numbers. In combination, numbers are thought to exceed 20,000 seasonally. A detailed count was made in December 1993. Speciesthat occurred in particularly high numbers included Phalacrocorax carbo, Anhinga rufa (98+), Mesophoyx intermedia, Threskiornis aethiopicus, Dendrocygna bicolor and D. viduata. Other waterbirds of interest noted in substantial numbers include Anastomus lamelligerus and Grus grus. Grus pavonina, Larus ichthyaetus, Larus cachinnans and Egretta gularis occur in smaller numbers, and both Botaurus stellaris and Podica senegalensis have been recorded. In addition Bahr Dar has the most northerly records in Ethiopia of Sarothrura rufa. A number of globally threatened species occur: Grus carunculatus, seen irregularly in small numbers; Phoenicopterus minor, whose numbers fluctuate unpredictably; Rougetius rougetii, resident in small numbers; Circus macrourus, fairly common during migration time, with a few overwintering; and Aquila clanga, recorded at the site but rare. A survey in March 1996 recorded 217 species, and more are known to occur. Asio abyssinicus, Parus leuconotus, Serinus xanthopygius and Lybius undatus are notable among the Afrotropical Highlands biome species. In addition, two Sudan–Guinea Savanna biome species have been recorded; see Table 3. Other species of interest include Nectarinia kilimensis, which has been reported on a number of occasions, and Lagonosticta rufopicta, which is fairly common. Ceratogymna brevis nests in the large figs around the lake, including in the grounds of the larger hotels in Bahr Dar, and both Picoides obsoletus and Cisticola eximia are known from the area to the west of Lake Tana.
Non-bird biodiversity: None known to BirdLife International.
Pressure/threats to key biodiversity
As Bahir Dar is the administrative centre for the region and has a large student population, there is a great need and opportunity for both formal and informal environmental education; the Bahir Dar Teacher’s College developed an Environmental and Family Life Education Centre in recognition of this need. As a consequence of the growing human population, the important area of forest on the Zege peninsula is fast being destroyed. Bahir Dar gets some of its fuelwood from this forest, but more is now being brought from areas further away to the west of Lake Tana. This ‘imported’ wood is brought to Zege and sent to Bahir Dar on ‘tankwas’. So far, there is little use of agrochemicals, so the lake remains free of such contamination. However, there is a growing industrial sector in Bahir Dar that uses water from the Abbay river and returns the spent water to the same source. It is hoped that the government will be able to get factory owners to control the quality of the effluent from their plants before industrial pollution becomes a serious issue. Farmers persecute the birds that damage their crops, in particular the cranes and geese.