Chien Lee / Harlequin Poison Dart Frog (Dendrobates histrionicus), Utria National Park, Colombia

Roland Seitre / Harlequin Poison Dart Frog (Dendrobates histrionicus) in defensive posture, native to South America

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

Thomas Marent / Harlequin Poison Dart Frog (Dendrobates histrionicus) on bromeliad, Cauca, Colombia

Pete Oxford / Poison arrow frog {Dendrobates histrionicus} Western Ecuador

Pete Oxford / Harlequin Poison Arrow Frog {Dendrobates histrionicus} Ecuador

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