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
Arctic Report Card video that summarizes the Report Card. In 2015, Arctic sea extent at the end of the winter was the lowest during the satellite record and the winter maximum occurred 15 days earlier than in the past. The sea ice minimum at the end of summer was the 4th lowest extent on record. These changes are having profound impacts in both the marine and terrestrial ecosystems and in sea surface temperatures. Arctic Report Card The National Oceanic and Atmospheric Administration's Arctic Report Card presents annually updated, peer-reviewed information on recent observations of environmental conditions in the Arctic relative to historical records.