Distribution within the USSR of Bewick's Swans Cygnus columbianus bewickii marked in Britain

Abstract

Between 1967 and 1989, 1,511 individual Bewick’s Swans wintering in Britain were marked with plastic leg-rings and, in some years, yellow dye on the tail and wing-tips, in order to determine their migratory sites and breeding areas within the USSR. Sightings and recoveries of marked Bewick’s Swans indicated that birds wintering at Slimbridge, Gloucestershire, GB and at Welney, Norfolk, GB migrate along the Baltic coast, traverse Karelia and Vologda on a broad front, and follow the north coast of the USSR to their breeding grounds. Two birds were recovered well outside this range; one in Perm, on the western side of the Ural mountains, and the other in Astrakhan. Of 68 reports of marked birds from the USSR, 36 (52.9%) were from Estonia and 9 (13.2%) were from the Pechora region. The group of Slimbridge-marked birds in the Pechora part of the breeding range suggests that these birds may perhaps form a sub-population that winters in Britain, although the results could also reflect regional differences in accessibility for human observers or a high density of Bewick’s Swans breeding in the area.