Anser anser (Linnaeus, 1758)
Anser cinereus M. et W.: Finsch, 1859: 386; Radakoff, 1879: 175; Hristovich, 1890: 221; Anser ferus (Gmel.): Elwes, Buckley, 1870: 339; Anser cinereus Meyer: Reiser, 1894: 182; Jordans, 1940: 143; Anser ferrus Brunn.: Klain, 1909: 143.
Conservation status: in Bulgaria: Endangered EN [B 2a, b(iv), c (iii, iv)], BDA-III; International: BeC-III, BoC-II.
General distribution. A Palearctic species breeding in the Scandinavian peninsula, Iceland, Great Britain, Central Europe, the Balkan peninsula, Byelorussia, the Ukraine, the European territory of Russia, Southwestern, Central and Asia.
Distribution and abundance in Bulgaria. A breeding summer visitor, passage migrant and winter visitor. In the past it mainly incubated in the larger marshes along the Danube and the lakes along the Black Sea coast, the numbers of the population not exceeding 25 pairs [1, 2]. At present it continues breeding irregularly in the known habitats. The breeding population varies between 5 and 25 pairs  and, according to recent estimates, 20-30 pairs . In the last 10 years, there was a tendency for a decrease of its numbers . During migration larger concentrations are registered along the Danube . For the 1977-1996 period, the average numbers of the wintering birds in the country were 793 (8-1532). Most of them winter along the Danube, where Srebarna Lake is of greatest significance (a maximum of 1 000 individuals in 1978). Since 1997, a decrease of the average numbers of the wintering birds has been observed .
Habitats. Lakes and marshes with vast reedbeds and a good nutrition base. On Persina Island, it also breeds in flooded willow forests, where it also spends the time for moulting.
Biology. The pairs occupy the breeding territory in February. It breeds singularly on a small island, amongst the reed or on a fallen old tree. Laying eggs takes place in March. The clutch contains 4-7 white eggs, and the first young ones appear in the middle of April; they start flying in about 50-60 days. The family is preserved in the autumn and the winter. The food contains different meadow plants. During the winter the birds feed in the fields with winter crops, together with the white-fronted goose .
Similar species. None.
Negative factors. Excessive overgrowth of the marshes with reed and rush (Persina Island); impermanent and unfavourable water regime; disturbance by fishermen, hunters, etc. (the lakes Durankulak and Srebarna); felling old willow forests (Persina Island); human poaching related to illegal shooting outside the hunting season at the end of the winter.
Conservation measures taken. Protected according to the Biological Diversity Act. Included in the Red Data Book of Bulgaria (1985). All contemporary habitats are in protected territories.
Conservation measures needed. Improvement and stabilization of the state of the existing wetlands in which it breeds. Elimination of the disturbance factor in most of them. Restoration of the wetlands on Perisna Island and Kalimok in a form that is closest to the initial one. Educational campaigns among hunters and a ban on shooting the species after 30 December.
References. 1. Red Data Book of Bulgaria, 1985; 2. Nankinov et al., 1997; 3 Kostadinova, 1997; 4. Nankinov et al., 2004; 5. BirdLife International, 2004; 6. Michev, Profirov, 2003.
Authors: Bozhidar Ivanov, Sergei Dereliev