Long-tailed Duck (Clangula hyemalis) ecology: insights from the Russian literature. Part 2: European part of the Russian breeding range

Long-tailed Ducks (Clangula hyemalis) breed around lakes in tundra vegetation and spend their winter at sea. Their most important wintering site in Europe is the Baltic Sea, and most of the birds wintering there breed in northern Russia. In light of recent population declines, particularly of the Baltic Sea wintering population, it is important to gather all available information for this species to better understand their life history, and to pinpoint the primary threats leading to their decline. Because non-English literature is often neglected, we compiled a review of the information collected in 101 Russian scientific articles published between 1895 and 2017 relevant to Long-tailed Ducks inhabiting the European part of Russia (from Pskov Lake to Yugor Peninsula). We focused on their distribution, breeding densities as well as breeding and feeding biology. The data overall show a similar breeding biology and timing compared to the Asian part of the breeding range. However, due to limitations of the geographical and temporal scope of the reviewed studies, recent trends cannot be detected. Therefore, comprehensive studies are required to understand the contribution of changes in the breeding grounds to population declines observed in the wintering grounds. The data summarized here can provide a basis for such studies, including repeat surveys that will help to understand population trends.