Tim Fitzharris / Gray Wolf (Canis lupus) dark morph, Montana

Edwin Giesbers / Red squirrel (Sciurus vulgaris) dark morph, in deep snow, Austria, Europe

Fabio Pupin / Western whip snake, (Hierophis viridiflavus), dark morph, basking in grass, Italy, April . Non-ex.

Terry Whittaker / Arctic fox (Alopex lagopus) female with blue colour morph winter coat walking along coast, Hornstrandir Nature Reserve, Iceland, April

Terry Whittaker / Arctic fox (Alopex lagopus) female showing blue colour morph, winter coat, scavenging in snow along the beach, Hornstrandir Nature Reserve, Iceland, April

Terry Whittaker / Arctic fox (Alopex lagopus) female showing blue colour morph, winter coat, walking on beach, Hornstrandir Nature Reserve, Iceland, April

Terry Whittaker / Arctic fox (Alopex lagopus) showing blue colour morph in winter coat, walking along snow. Hornstrandir, Westfjords, Iceland. April

Terry Whittaker / Arctic fox (Alopex lagopus) showing blue colour morph in winter coat, walking along snow. Hornstrandir, Westfjords, Iceland. April

Terry Whittaker / Arctic fox (Alopex lagopus) showing blue colour morph in winter coat, walking along snow. Hornstrandir, Westfjords, Iceland. April

Marie Read / Reddish Egret (Egretta rufescens) dark morph, breeding plumage, with outspread wings, chasing fish, Fort De Soto Park, Florida, USA

Marie Read / Reddish Egret (Egretta rufescens) dark morph, breeding plumage, with outspread wings looking for fish, Fort De Soto Park, Florida, USA

Gerrit Vyn / Gyrfalcons (Falco rusticolus) pair, with white-morph male and a dark-morph female. Seward Peninsula, Alaska. May.