Aythya nyroca Guldenstaedt, 1770
Fuligula nyroca Staph.(L.): Elwes & Buckley, 1870: 340; Reiser, 1894: 188; Klain1909: 156; Anas ferina: Homeyer, 1877: 73; Nyroca ferina (L.): Boetticher, 1927: 184; Prostov, 1964: 51.
Conservation status: in Bulgaria: Vulnerable VU [Alc+B2a,b,c+B3a,b+C1+E], BDA-III; International: IUCN-NT, BeC-III, BoC-I, II, ECS-Spec 1, BD-I.
General distribution. A Turkestan-Mediterranean species with a fragmented area in the moderate climatic region of the Palearctic, in the steppes, semi-desert and southern forest zone of Western Europe, Northern Africa and Mongolia. .
Distribution and abundance in Bulgaria. A breeding summer visitor, passage migrant and winter visitor. At the end of the 19th century it was widely distributed and numerous [2, 3]. It is now common along the Danube and the Black Sea coast [4, 5]. Since the middle of 20 century, a reduction in the numbers has been observed . Until the middle of the 1990s, 20 breeding places were known with 100-150 pairs [7, 8]. During mapping in 1997, 35 habitats were registered, with 150 – 210 pairs . In 2002, the disappearance of 13 breeding places (of a total of 35) was reported but another 8 were found, new, and a total of 185 pairs registered. The breeding population varies from 150 to 230 pairs [10, 11, 12]. In June-August, along the Danube, gatherings of up to 3 000 individuals have been recorded . Rare during the winter: from 0 to 70 individuals ; more regular wintering was registered after 1996 [14, 15].
Habitats. Mainly shallower fish farms, marshes and microreservoirs with mosaically situated vegetation, large reedbeds with small water mirrors and canals, with sloping shores and slimy shallows and hydrophytic vegetation . During migrations: various wetlands. During wintering: lakes, reservoirs and small sea bays along the Black Sea coast.
Biology. It starts breeding in the second half of May, incubating in marshy vegetation or on the shore, in close vicinity to the water. It lays 8-10 (5-14) eggs [8, 13]. It mainly feeds on vegetation, also on water invertebrates and larvae of insects.
Similar species. A monotypical species.
Negative factors. Drying up of the wetlands, abandonment and/or intensification of fish farms, disturbance by fishermen and tourists. The markedly changeable water level in the breeding places.
Conservation measures taken. Protected according to the Biological Diversity Act. Included in the Red Data Book of Bulgaria (1985). The major breeding places are in Protected Territories and Protected Zones. Management Plans have been developed for the lakes Poda, Srebarna, Shabla and Durankulak.
Conservation measures needed. Updating of the National Plan for the preservation of the species, of the Management Plans and of the plans for the restoration of wetlands that are important breeding places. Development of Management Plans and of appropriate measures for the other important habitats.
References. 1. Scott, Rose, 1996; 2. Finsch, 1859; 3. Elwes & Buckley, 1870; 4. Radakoff, 1879; 5. Reiser, 1894; 6. Patev, 1950; 7. Nankinov, 1985; 8. Nankinov et al., 1997; 9. Petkov, 1997; 10. Petkov, 2004; 11. Petkov, in press; 12. Iankov, in press; 13. Del Hoyo, Elliot, Sargatal, 1992; 14. Kostadinova, Dereliev, 2001; 15. Michev, Profirov, 2003.
Author: Nikolai Petkov