Great Bittern
Botaurus stellaris (Linnaeus, 1758)
Order Ciconiiformes
Family Ardeidae
Conservation status: in Bulgaria: Endangered EN D, BDA-II, III; International: BeC-I, BoC-I, BD-I.
General distribution. A Palearctic species breeding in Europe, Central and Eastern Asia and Northwestern Africa. It winters in Greece, Turkey, Southern and Eastern Asia, Africa.
Distribution and abundance in Bulgaria. Resident. Until the middle of the 20th century it was frequently found in the large water basins (marshes in the Sofia field, in the marshes of the towns of Batak, Straldzha and Radomir and in the Upper Thracian lowland), along the Danubian and the Black Sea coast [1, 2], usually at altitudes under 600 m. [3]. With the drying up of the marshes after the 1950s, its population thinned. It breeds along the Black Sea coast (the lakes Durankulak, Shabla, Atanasovsko and the Poda Protected Site, Burgas region), in the Danube valley (the Kalimok locality, the fish farms near the village of Mechka and the village of Hadzhidimitrovo, at places in the Upper Thracian lowland and Western Bulgaria [2]. In the second half of 1990s, it increased its numbers in the lakes Shabla and Durankulak, in the Dragoman Marsh, in the fish farms of Hadzhi Dimitrovo, etc., but declined or disappeared from the former fish farms of Kalimok, from Srebarna Lake, etc. [2, 4]. It was reported for Persina Island, the lakes Durankulak, Varna and Atanasovsko, near the villages of Trivoditsi, Lebed and Gorno Ezerovo, [1]. Wintering birds were found in Aldomirovsko Blato marsh, the lakes Vaya, Mandrensko, Shabla and Durankulak, near the village of Bezden, the Rupite locality (Petrich region), the Poda Protected Site [4]. Observed in the Burgas lakes between 12 March and 21 October [5], during the spring migration in the fish farms in the Ormana locality (Yambol region) and during the autumn migration in Shabla Lake [4]. The numbers are declining: 25-30 [1], 10-50 [6], 40-50 [7], to 20-70 breeding pairs [8]. During the mapping of the breeding ornithofauna in the country, it was found in 38 breeding habitats: 18 certain, 7 probable and 13 possible [9].
Habitats. Vast water basins with reed – marshes and lakes. It breeds in reedbeds (over 20 ha), with depths of up to 30 cm. The species depends on the presence of stagnant freshwater and brackish water basins.
Biology. It breeds in singular isolated habitats. In many of them only singular courting males are found, and in others (the lakes Durankulak and Shabla, the marshes Tsibarsko and Dragomansko) – 3-4 courting birds in each. Polygamous: one male has up to 5 females. It lays 3-7 eggs that it incubates for 25-26 days. It feeds on frogs, mouse-like rodents, crayfishes, fish, etc. [10].
Similar species. None.
Negative factors. Destruction of the habitats, illegal shooting, food insufficiency, disturbance.
Conservation measures taken. Protected according to the Biological Diversity Act. Included in the Red Data Book of Bulgaria (1985). Some breeding habitats (the lakes Atanasovsko, Shabla and Durankulak, the Poda locality) are in Protected Natural Territories.
Conservation measures needed. Inclusion of the permanent, traditional breeding habitats (the fish farms near the village of Mechka and the village of Hadzhidimitrovo) in protected natural territories.
References. 1. Boev, 1985; 2. Petkov, Boev, in press; 3. Simeonov et al., 1990; 4. Collections of Natural History Museum, BAS; 5. Prostov, 1964; 6. Kostadinova, 1997; 7. Nankinov et al., 2004; 8. BirdLife International, 2004; 9. BSPB, in press; 10. Boev, 1962.
Authors: Zlatozar Boev, Nikolai Petkov
