page_title: Snow camouflage
section_title: Seasonal polyphenism
hierarchical_section_title: Snow camouflage / Among animals / Seasonal polyphenism
caption_attribution_description: Picture of the Alaskan Ptarmigan in Denali National Park. Camera and Exposure Details:Camera: Canon PowerShot S1 ISLens: Canon 1:2.8-3.1 USM 10x Zoom LensExposure: 58mm (380mm in 35mm equivalent) f/4.5 @ 1/160 s.
context_page_description: Snow camouflage is the use of a coloration or pattern for effective camouflage in winter, often combined with a different summer camouflage. Summer patterns are typically disruptively patterned combinations of shades of browns and greys, up to black, while winter patterns are dominated by white to match snowy landscapes.
  Among animals, variable snow camouflage is a type of seasonal polyphenism with a distinct winter plumage or pelage. It is found in birds such as the rock ptarmigan, lagomorphs such as the Arctic hare, mustelids such as the stoat, and one canid, the Arctic fox. Since these have evolved separately, the similar appearance is due to convergent evolution. This was used as early evidence for natural selection. Some high Arctic species like the snowy owl and polar bear however remain white all year round.
  In military usage, soldiers often either exchange their disruptively-patterned summer uniforms for thicker snow camouflage uniforms printed with mainly-white versions of camouflage patterns in winter, or they wear white overalls over their uniforms. Some armies have made use of reversible uniforms, printed in different seasonal patterns on their two sides.
context_section_description: Some animals of the far north, like the showshoe and Arctic hares, Arctic fox, stoat, and rock ptarmigan change their coat colour (by moulting and growing new fur or feathers) from brown or grey summer camouflage to white in the winter; the Arctic fox is the only species in the dog family to do so. However, Arctic hares which live in the far north of Canada, where summer is very short, remain white year-round. Since these animals in widely separated groups have evolved separately, the similarity of coloration is due to convergent evolution, on the presumption that natural selection favours a particular coloration in a particular environment.
  The seasonal polyphenism in willow grouse differs between Scottish and Scandinavian populations. In Scotland, grouse have two plumages (breeding and non-breeding), while in Scandinavia there is a third plumage, a white winter morph. The genetic basis for this is not in the melanin pigment system, and is probably due to regulatory changes. The behaviour of moulting females in springtime depends on their plumage state: they tend to sit on snow while they are mainly white, but choose the border between bare ground and snow when they have more dark feathers. They seem to be choosing the best compromise between camouflage and food quality.
  Climate change from global warming is leading to a mismatch between the seasonal coat coloration of arctic animals such as snowshoe hares with the increasingly snow-free landscape.
caption: Willow grouse of Northern forests and tundra change plumage in winter; British population (red grouse) does not.
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