Steve Knell / Harlequin duck (Histrionicus histrionicus) portrait of male stood motionless on exposed rock, in river, Iceland, May

Steve Knell / Harlequin ducks (Histrionicus histrionicus) male chasing female on riverbank, Iceland, May

Steve Knell / Harlequin duck (Histrionicus histrionicus) male standing in rapids, Iceland, May

Gerrit Vyn / Two pairs of Harlequin Ducks (Histrionicus histrionicus) in flight. Ocean County, New Jersey, USA, January.

Orsolya Haarberg / Harlequin duck (Histrionicus histrionicus) female. Laxa River, Mvatn, Iceland. June 2008

Orsolya Haarberg / Harlequin duck (Histrionicus histrionicus) male. Laxa River, Mvatn, Iceland. June 2008

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 / 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