Coloration evidence for natural selection J. Bowler wrote that Darwin's theory In his 1889 book "Darwinism", the naturalist Alfred Russel Wallace considered the white coloration of Arctic animals. He recorded that the Arctic fox, Arctic hare, ermine and ptarmigan change their colour seasonally, and gave "the obvious explanation", that it was for concealment. The modern ornithologist W. L. N. Tickell, reviewing proposed explanations of white plumage in birds, writes that in the ptarmigan "it is difficult to escape the conclusion that cryptic brown summer plumage becomes a liability in snow, and white plumage is therefore another cryptic adaptation." All the same, he notes, "in spite
Ptarmigan Traverse of the trip. Today the route is a common goal of Cascade Range mountaineers. Place names are listed from north to south: Ptarmigan Traverse Ptarmigan Traverse is an alpine climbing route in the North Cascades of Washington State. The route, from Cascade Pass to Dome Peak, is generally remote, unmarked, and challenging, traversing rugged terrain and several glaciers. The first traverse took 13 days in July 1938. The group consisted of four members of the Ptarmigan Climbing Club: Bill Cox, Calder Bressler, Ray W. Clough, and Tom Myers. The second traverse was in 1953 and consisted of Dale Cole, Bob