Dispersal History and Current Breeding Range of the Mute Swan (Cygnus olor, Anatidae, Aves) in Northwestern Russia

Throughout the 20th century and the first decades of the current century, the Mute Swan, Cygnus olor, has been growing in numbers and expanding its range both northward and northeastward. The history of the introduction of this species into northwestern Russia and the main stages of its expansion, as well as the peculiarities of its spatial distribution in the region, are discussed. The Mute Swan started breeding in northwestern Russia in the mid-1980s. The species settled in two landscapes: on shallow eutrophic lakes and on sea moraine and selga islands. To date, the species range covers the eastern part of the Gulf of Finland, the western and southwestern parts of Leningrad oblast, all of Pskov oblast, and the westernmost parts of Novgorod and Tver oblasts. It is noteworthy noting that at the initial stages of expansion the first breeding pairs appeared throughout most of the above-mentioned territories at once. Subsequently, new nests were recorded mainly within the “occupied zone” delineated by the first newcomers. Over more than 30 years of expansion, the range of this species moved eastwards by no more than 88–94 km into different localities, while during the previous 20 years (1960–1980) the range of the Mute Swan in Scandinavia moved up to 998 km. Decreasing rates of range expansion amid the continued development of a warm phase of the climate suggest the presence of some kind of climatic barriers for the species in the region.