Oscar Dewhurst / Mute swan (Cygnus olor), two cygnets sheltering under parent's wing. Richmond Park, London, England, UK. April.

Oscar Dewhurst / Mute swan (Cygnus olor) swimming with cygnets in misty lake in morning light. Richmond Park, London, England, UK. May.

Wim van den Heever / Whooper swan (Cygnus cygnus) mid flight over the frozen lake, Kussharo, Hokkaido, Japan.

Wim van den Heever / Whooper swan (Cygnus cygnus) portrait, on frozen lake Kussharo, Hokkaido Japan, February.

Espen Bergersen / Harlequin duck (Histrionicus histrionicus) male holding female under water as part of copulation. Iceland

Espen Bergersen / Pair of Harlequin duck (Histrionicus histrionicus) in river stream. Myvatn, Iceland.

Espen Bergersen / Harlequin duck (Histrionicus histrionicus) in river stream. Myvatn, Iceland. May.

Espen Bergersen / Barrow's goldeneye (Bucephala islandica) in partly frozen lake. Iceland, May.

Espen Bergersen / Whooper swan (Cygnus cygnus). Iceland

Espen Bergersen / Harlequin duck (Histrionicus histrionicus) Jokulsarlon lake. Iceland 2016

Espen Bergersen / Pair of Harlequin duck (Histrionicus histrionicus) Jokulsarlon lake. Iceland. May.

Espen Bergersen / Harlequin duck (Histrionicus histrionicus) male, Iceland