Wintering of Anseriformes on the Commander Islands: Current State and Historical Review
New data and analysis of changes in the number of wintering Anseriformes on the Commander Islands, the northernmost wintering site in the Far East, are presented. The surveys were carried out in March 2015-2019, mainly overland and covering 61 % of the coast of Bering Island, with 100 % of the coast in 2015 as an exception. Boat surveys of A. canagicus were carried out separately in the southwestern part of the island in April. In total, 17 species were encountered, including 12 recorded regularly, and 5 not annually. On Medny Island, the survey was carried out once, on April 3-4, 2017, by boat, and covered the entire coast. There, 7 species were taken into account. The total number of wintering Anseriformes of the Commander Islands is about 21 thousand birds, including 18.5 thousand on Bering Island and 2.5 thousand on Medny Island. The majority is concentrated in the northern and central part of Bering Island; in the south, the number is much lower. The dominant species is H. histrionicus: 65-72 % on Bering Island and 63 % on Medny Island. Subdominant is P stelleri (16-20 % on Bering Island) as well as S. mollissima (30 % on Medny Island). The density of birds in the northern and central parts of Bering Island is 90-111.5 individuals per km of the coastline; in the south of the island, there are about 12 individuals; and on Medny Island, 14.9 individuals per km of the coastline. Over the past 25 years, the numbers of A. canagicus, A. platyrhynchos, A. acuta, B. clangula, andM. serrator have increased. P stelleri and C. hyemalis have decreased. A. penelope, M. americana, and B. albeola began to regularly occur at the wintering, and B. bernicla, A. crecca, and A. marila have been observed more often than before. M. deglandi and M. merganser are now more common during migration, and practically are not observed at the wintering.