Current State and Development Factors of Northern Gannet (Morus bassanus, Sulidae, Aves) Colonies in the Russian Sector of the Barents Sea

The results of long-term observations of the colonization of coastal islands of the Murman Coast, Barents Sea, by northern gannets (Morus bassanus (L. 1758)) are presented. The formation of colonies on the islands of the Murman Coast is shown to be associated with recovery of the stocks of young Atlantic herring in the Barents Sea in the 1990s–2000s together with an intense influx of birds from the Norwegian part of the species range. Additionally, the population dynamics of the species in two Russian colonies are analyzed. The end of the last decade and the beginning of this decade were marked by a surge in population numbers in both Russian colonies. To date, the overall range of this species includes the southern part of the Barents Sea and the entire water area of the White Sea with the eastern limit of its breeding range being confined to Kharlov Island (Eastern Murman) in the Barents Sea. Beginning in 2022, the population dynamics in the westernmost Russian colony have been governed by mortality due to the HPAIV avian influenza epidemic, threatening further development of both Russian colonies. In the summer of 2023, using the phenotypic indicator of the previous infection, the number of sick birds in the colony was determined to account for 13–15% of the total number of the locally nesting individuals.