Podiceps grisegena (Boddaert, 1783)
Podiceps rubricollis Gm.: Reiser, 1894: 203; Colymbus rubricollis Lath.: Klain1909: 182; Pedetaithyia griseigena Bodd.: Boetticher, 1927: 28; Colymbus griseigena Bodd.: Grossler, 1967: 228; Podiceps griseigena (Bodd.): Patev, 1950: 254.
Conservation status: in Bulgaria: Endangered EN [A2a, c; B1a, c(iii)], BDA-III; International: BeC-II, BoC-II.
General distribution. A Holarctic species breeding in Northern and Eastern Europe, Asia and Northern America.
Distribution and abundance in Bulgaria. A breeding summer visitor, rarely winters. In the past stable breeding habitats were the marshes on Persina Island, Srebarna Lake, the Garvansko Marsh, Vaya Lake and Aldomirovsko Blato marsh [1, 2]. At present, it mainly breeds in the larger marshes and fish farms near the Danube [3, 4]. It multiplies irregularly in the fish farms near the city of Pazardzhik and the village of Sokolotsa, Plovdiv region. It does not breed in the Burgas lakes . Its breeding in Durankulak Lake in the recent years has not been confirmed. In the 1995-2002 period, its numbers showed a negative trend . The breeding population does not exceed 10-30 pairs. In the last 5 years a slight increase of the wintering birds was registered  but the numbers are insignificant.
Habitats. Freshwater lakes, marshes, fish farms, etc., overgrown with abundant water vegetation. During migration and during the winter, in the same biotopes, in reservoirs and in the sea.
Biology. It breeds in small thinned colonies. It builds a floating nest amongst the water vegetation. Laying eggs takes place mainly in May. The clutch contains 2-6 eggs. It incubates for about 25 days. The young ones are nidifugous. Sexual maturity is reached in the second year .
Similar species. The Great Crested Grebe (Podiceps cristatus).
Negative factors. Overgrowing with reed and rush of a large part of the fish farms. The impermanent water regime in the reserves Persina and Srebarna.
Conservation measures taken. Protected according to the Biological Diversity Act. Included in the Red Data Book of Bulgaria (1985). Some of the habitats are situated in reserves: Persina, Srebarna or other protected territories (Durankulak Lake), for which Management Plans have been adopted.
Conservation measures needed. Improvement of the water regime and thinning of the vegetation in the major habitats. Restoration of the Kalimok Wetland. Preservation in the fish farms in which it breeds.
References. 1. Red Data Book of Bulgaria, 1985; 2. Simeonov et al., 1990; 3. Shurulinkov et al., 2005; 4. Kambourova, 2005; 5. Dimitrov et al., 2005; 6. BirdLife International, 2004; 7. Michev, Profirov, 2003.
Authors: Bozhidar Ivanov, Nikolai Petkov, Victor Vasilev