Shelduck
Tadorna tadorna Linnaeus, 1758
Order Anseriformes
Family Anatidae
Conservation status: in Bulgaria: Vulnerable VU B(1a,2a)+D, BDA-III; International: BeC-II; BoC-II.
General distribution. Probably a Sarmatian species breeding in Europe and Asia. The largest European populations are in Russia 7 500 – 11 000, Sweden 6 000 – 8 000, the Netherlands 5 000 – 8 000, Great Britain 5 800 – 10 800 breeding pairs.
Distribution and abundance in Bulgaria. A breeding summer visitor, passige migrant and winter visitor. It mainly breeds along the Black Sea coast, in the past it also bred along the Danube [1, 2]. At present, the total population is estimated at 30 – 65 breeding pairs [3]. During migration and wintering it is mainly concentrated along the Black Sea coast, less frequently within the country. Its largest concentrations have been registered during the winter in the lakes Atanasovsko and Pomoriysko, in the Southern Black Sea coast its total numbers being 2 081 at the average, with a maximum of 4 224 [4, 5, 6].
Habitats. Shore water basins, sea shallows, stony shores, vertical shores of stone and sand quarries, saltworks, tailings-ponds.
Biology. For breeding it uses old holes of foxes, badgers, underground hares, etc. etc. or digs them up alone in leoss shores. Less often it breeds in the hollows of trees or in reedbeds. It lays 5 – 12 white eggs. Incubation continues for 29 - 31 days and the clutch consists of 9 young ones at the average [8]. The young ones start flying at the age of 45 – 50 days, sexual maturity is reached in the second year [7, 8]. Feeding has been insufficiently studied (in the stomachs analyzed, small crustaceans have been found) [9].
Similar species. The Ruddy Shelduck (Tadorna ferruginea).
Negative factors. Loss of habitats and urbanization of a large part of the shore; eutrophication and drying up of the wetlands; increase of the numbers of the Jackal.
Conservation measures taken. Protected according to the Biological Diversity Act., included in the Red Data Book of Bulgaria (1985). The major biotopes along the Black Sea coast are declared Protected Territories and Ramsar Sites. In the lakes Atanasovsko and Pomoriysko, islands are made and dikes are enclosed for stopping predators. For Atanasovsko Ezero lake, a Management Plan has been adopted, including particular activities for the species.
Conservation measures needed. Preparation of a National Plan for its preservation, increase of the ecological culture of the population.
References. 1. Nankinov, 1985; 2. Nankinov et al., 1997; 3. Iankov, in press; 4. Michev, Profirov, 2003; 5. Dimitrov et al., 2005; 6. Michev et al., 2004; 7. Cramp, Simmons, 1977; 8. Georgiev, 1976; 9. Prostov (1964); 10. Profirov, Michev, 2003.
Author: Lyubomir Profirov
