White-tailed ptarmigan summer plumage. The finely-barred greyish coloration on the back makes it easy to distinguish this species from the much browner willow ptarmigan and rock ptarmigan. Both sexes maintain white tail and wing feathers all the year and males can be identified by their reddish eyecombs (fleshy growths above the eye), also present year-long. In general this bird is silent but it sometimes makes quiet, low-pitched hoots and soft clucking noises. The white-tailed ptarmigan is an alpine species, a permanent resident of the high mountains above or near the timber line. It occupies open country and flies a great deal more
Arctic fox regulation. Also, the Arctic fox has a beneficial mechanism in their nose for evaporative cooling like dogs, which keeps the brain cool during the summer and exercise. The thermal conductivity of Arctic fox fur in the summer and winter is the same; however, the thermal conductance of the Arctic fox in the winter is lower than the summer since fur thickness increases by 140%. In the summer, the thermal conductance of the Arctic foxes body is 114% higher than the winter, but their body core temperature is constant year-round. One way that Arctic foxes regulate their body temperature is by