The whooper swan (Cygnus cygnus), also known as the common swan, is a large northern hemisphere swan. It is the Eurasian counterpart of the North American trumpeter swan, and the type species for the genus Cygnus.
Whooper swans can migrate hundreds or even thousands of miles to their wintering sites in southern Europe and eastern Asia. They breed in the subarctic Eurosiberia, further south than Bewicks in the taiga zone. They are rare breeders in northern Scotland, particularly in Orkney, and no more than five pairs have bred there in recent years; a handful of pairs have also bred in Ireland in recent years. This bird is an occasional vagrant to the Indian Subcontinent and western North America. Icelandic breeders overwinter in the United Kingdom and Ireland, especially in the wildfowl nature reserves of the Royal Society for the Protection of Birds and the Wildfowl and Wetlands Trust.