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 (sternwheeler) allowed the vessel to be more capable of pushing barges, which increased the vessel's utility and effective cargo capacity. "Ptarmigan" was placed on the Columbia River route that began at Golden and ran south, at least during high water, to Columbia Lake, the ultimate source of the Columbia River. In 1903, soon after completion, "Ptarmigan" was sold to the Columbia River Lumber Company, which hired Armstrong to manage its steamboat operations. In 1907 "Ptarmigan" hit a snag and sank (A snag is a sunken log jammed in the river bottom but sticking up through the water to just below the