Gadwall
Anas strepera Linnaeus, 1758
Chaulelasmus strepera Gray ex Lin.: Hristovich, 1890: 222; Boetticher, 1927: 184.
Order Anseriformes
Family Anatidae
Conservation status: in Bulgaria: Critically endangered CR=C [2+2(a(i))], BDA-III; International: BeC-III, BoC-II, BD-I.
General distribution. A Palearctic species. It breeds in Europe, Asia, and Central Northern America. In Europe, the area is markedly split into separate habitats, isolated one from the other. In the north it reaches 60° N, and in the south up to 35° N.
Distribution and abundance in Bulgaria. A breeding summer visitor, passage migrant and wintering species, in the past it was common and numerous throughout the country [1, 2]. It started to decline in the middle of the 20th century [3]. Since the end of the 20th century to the present day, the breeding distribution has been preserved, located along the wetlands of the Danube and the Black Sea coast [4, 5]: the Orsoya Fish Farms Protected Locality, the Kalimok-Brashlen Natural Park, Persina, the Mechka Fish Farm, the Srebarna Natural Reserve and the complex of wetlands around the city of Burgas [6, 7]. In the other breeding places, there are only separate pairs pairs. In the 1980s, the numbers were estimated at 30-50 pairs pairs [4]. In the 1996 – 2002 period it varied withing 50 – 80 pairs [6]. During migration it is found throughout the country [5]. In the winter it is regularly observed, but in small numbers (10-100 individuals) [8]. For the period 1977-2001, about 70 birds at the average (a maximum of 129 /1991) [9], mainly in Southern Bulgaria and along the Black Sea coast [5].
Habitats. Various wetlands. Along the Danube, in marshes and lakes with rich submerged vegetation and large reedbeds, in the region of the Burgas lakes in water basins with a large open water surface and vegetation located along the periphery [6]. During migration and wintering in various wetlands, including slow flowing rivers and sea bays [5].
Biology. It breeds from the second half of April and the beginning of May. It incubates most often on the shore in high marsh vegetation, amidst the grass or under bushes. The nest is covered with grass and down, it lays 8-12 eggs. Basically a plant-eating species: seeds and different parts of water and hydrophyte plants. Cases have been described of cleptoparasitism with respect to other water birds [10].
Similar species. Monotypical, no similar species.
Negative factors. Destruction and damaging of the habitats, disturbance during the breeding season.
Conservation measures taken. A protected species as of 1962, included in the Red Data Book of Bulgaria (1985). The major habitats along the Danube are protected territories: Orsoya, Srebarna, Kalimok and Belene island; restoration of the water regime is envisioned for the last two wetlands. Along the Black Sea coast, Yatata and Poda are also protected. Management Plans have been developed for lakes Poda and Srebarna.
Conservation measures needed. Updating of the National Plan for the conservation and restoration of the wetlands in Bulgaria. Development of management plans and plans for the restoration of the wetlands in which the species nests. Development and implementation of appropriate agro-ecological measures for the fish farms, aimed at preservation and attraction to nesting.
References. 1. Reiser, 1894; 2. Radakoff, 1879; 3. Patev, 1950; 4. Nankinov, 1985; 5. Nankinov et al., 1997; 6. Petkov, in press; 7. BSPB, in press; 8. Kostadinova, 1997; 9. Michev, Profirov, 2003; 10. Del Hoyo, Elliot, Sargatal, 1992.
Author: Nikolai Petkov
