Willow ptarmigan a reddish hue to the neck and breast, a black tail and white wings and underparts. It has two inconspicuous wattles above the eyes, which become red and prominent in the breeding season. The female is similar in appearance but lacks the wattles and has brown feathers scattered among the white feathers on the belly. During winter, the plumage of both sexes becomes completely white, except for some black feathers in the tail. Immature birds resemble the adults. The willow ptarmigan can be distinguished from the closely related rock ptarmigan ("Lagopus muta") by its larger size and thicker bill and
Ocean acidification in the Arctic Ocean has also allowed more Pacific water to flow into in the Arctic ocean during the winter, this is called Pacific winter water. The Pacific water flows into the Arctic ocean carrying additional amounts of carbon dioxide by being exposed to the atmosphere and absorbing carbon dioxide from decaying organic matter and from sediments. The Arctic ocean pH levels are rapidly decreasing because not only is the ocean water absorbing more carbon dioxide due to increased surface area exposure as a result of a decrease in sea ice. It also has large amounts of carbon dioxide being transferred to the Arctic