Konstantin Mikhailov / Trumpeter Swans (Cygnus buccinator) on lake, during migration through Denali mountainous tundra area, Denali Road in Alaska, North America. September.

Konstantin Mikhailov / Trumpeter Swan (Cygnus buccinator) on lake, during migration through Denali mountainous tundra area, Denali Road in Alaska, North America. September.

David Kjaer / Small flock of Bewick's / Tundra swans (Cygnus columbianus) on water, in snow covered landscape, Gloucestershire, England

Philippe Clement / The Alaska Range and Wonder Lake with Tundra swans {Cygnus columbianus} Denali NP, Alaska, USA.

Philippe Clement / The Alaska Range and Wonder Lake with Tundra swans {Cygnus columbianus} Denali NP, Alaska, USA.

Nigel Bean / Whistling / Tundra swan {Cynus columbianus} portrait

Jim Brandenburg / Tundra Swan (Cygnus columbianus) trio flying against cloudy sky, Minnesota

Jim Brandenburg / Tundra Swan (Cygnus columbianus) flock taking off from lake, Mattamuskeet National Wildlife Reserve, North Carolina

Nick Upton / Bewick's swan (Cygnus columbiana bewickii) flapping its wings as it stands on a frozen marshland pool, Gloucestershire, UK, February.

Nick Upton / Bewick's swan (Cygnus columbiana bewickii) sliding on ice as it lands on a frozen marshland pool with other swans and Canada geese (Branta canadensis) in the background, Gloucestershire, UK, Febru...

Nick Upton / Bewick's swan (Cygnus columbiana bewickii) sliding on ice after landing on a frozen marshland pool, Gloucestershire, UK, February.

Nick Upton / Bewick's swan (Cygnus columbianus bewickii) in flight overhead, Gloucestershire, UK, February.