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
Winter white dwarf hamster the body weight ranges from , and in females, . In human care, they are slightly heavier. The average lifespan of the Winter white hamster is one to three years in captivity, though they can live longer. In the wild, they are known to live as little as one year. In summer, the fur of the Winter white hamster on the back changes from ash-grey to dark brown, or sometimes pale brown with a tint. The face changes to grey or brown, while the mouth area, the whisker area, and the ears are slightly brighter. The outer ears and the