Snow camouflage as Hugh B. Cott have echoed his observations, adding that other animals of the Arctic such as musk ox, moose, reindeer, wolverine and raven never become white "even in the coldest parts of their range". Cott noted that both animals that hunt, like polar bear and stoat, and prey animals like ptarmigan and mountain hare, require camouflage to hide from prey or from predators respectively. There is little experimental evidence for the adaptiveness of white as camouflage, though the ornithologist W. L. N. Tickell, reviewing proposed explanations of white plumage in birds, writes that in the ptarmigan "it is difficult
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