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 Tunnel doors were hung across the tunnel adits during the summer of 1975. They remain open from mid-July until October 1, weather permitting. The long tunnel is a unique man-made feature in Glacier. This trail tunnel embodies exceptional qualities of landscape architecture and engineering in a pedestrian-scaled tunnel, cut through a sheer mountain wall. Ptarmigan Tunnel The Ptarmigan Tunnel was built in 1930 through the Ptarmigan Wall at an elevation of in Glacier National Park, near Many Glacier. The tunnel allows hikers to avoid a strenuous climb over very steep terrain between Many Glacier and the Belly River valley. Two opposing