Whooper Swan populations occur in the Western Palearctic and Asia; the Iceland population which winters in Iceland, Britain and Ireland; the Northwest Europe population which winters primarily in Denmark, Schleswig-Holstein and Mecklenburg (Germany), and The Netherlands; a third population, thought to occur in western Siberia, the Black Sea and eastern Mediterranean; and a fourth in the Central Siberia/East Asia region. The degree of exchange between these populations, and the flyways used, remains uncertain.

The first co-ordinated census of the Iceland population took place in January 1986 and recorded 16,742 individuals. Over 20,600 were recorded during the census in January 2000.

Most Whooper Swans from the Iceland population migrate to winter at various sites in Ireland and Britain. A small proportion remains in Iceland, while small numbers are encountered in countries bordering the southern North Sea. Whooper Swans from the Northwest Europe population have also been recorded in Britain in small numbers.