In Washington more fishers live in the Olympic Peninsula and the northern Cascade Mountains than elsewhere. A few may occur in northeastern Washington, the Blue Mountains and the Willapa Hills.
The name pacifica was regarded by [Grinnell], Dixon, and Linsdale (1937: 217) as a synonym of pennanti.
Mustela erminea Linnaeus
Ermine
Description.—Though it is similar in general characters and proportions to the long-tailed weasel, the ermine is much smaller and has a relatively shorter tail. It is darker and less reddish or yellowish in summer. Adult males measure about 10 inches in length, of which 3-1/2 inches is the length of the tail. Females measure about 8 inches and have tails 2 inches long. The upper parts are chocolate brown; the underparts are white or pale yellow. Along the coast of Washington, the pale color of the underparts is more restricted in the ermine than in the long-tailed weasel. The dark brown tail has a black tip. Ermines east of the summit of the Cascades become pure white in winter, save for the black tail tip. West of the summit of the Cascades the winter pelt is similar to the summer pelt but is slightly paler with denser underfur.
Ermines in America range from the Arctic southward, in mountainous areas, to the southern end of the Sierra Nevada in California, and in the Rocky Mountains to northern New Mexico. In Washington they are found over the entire state except the arid parts of eastern Washington, where only the long-tailed weasel occurs. So far as my observations go, the ermine is principally nocturnal in Washington; I have seen only one abroad in the daytime. It dashed from a roadside thicket near Glacier, Whatcom County, and was crushed beneath the wheels of a car. [Taylor] and [Shaw] (1927: 53) note several instances of diurnal activity of the ermines at Mount Rainier National Park.
The ermine seems to feed principally upon mice. Its small size adapts it to entering burrows that larger weasels cannot enter. It probably eats chipmunks, birds, and other small, warm-blooded animals. Ermines climb readily and are often taken in traps set in trees for martens. Near Skykomish, King County, William Hoffman took two ermines in traps set in burrows of mountain beavers. The mountain beavers were needed for use as bait on his trap line. The traps were reset and later caught mountain beavers. Seemingly the ermines were traveling through the burrows, perhaps to catch the mice which utilize the burrows as highways, rather than to prey upon mountain beavers. It is difficult to see how the tiny ermine could kill an adult mountain beaver, which outweighs it many times. Should the incisors of the mountain beaver close even once upon an ermine it would most certainly be seriously wounded or killed. Judging by the forest habitat occupied by the ermine in Washington, one might expect its principal food to consist of deer mice (Peromyscus maniculatus), red-backed mice (Clethrionomys) and meadow mice (Microtus).
In observing the activities and habits of mammals in their natural habitat, I have often relied on tracking in fresh snow. Strangely enough, tracks of ermines were seldom found, and the few that were seen came from beneath a log, bush or wind-fall and disappeared beneath similar cover, rarely extending 20 feet on the surface of the snow. The larger, long-tailed weasels often traveled for miles on the surface of the snow. Possibly the ermines were following the burrows of mice through the snow, or perhaps they kept beneath the surface from fear of owls. This suggests a reason why ermines are so seldom seen abroad. They may be following burrows and runways of mice and seldom come to the surface of the ground.
On November 18, 1936, we saw three ermines and two long-tailed weasels taken by a trapper on Deception Creek near Stevens Pass, King County. All were in the white winter coat. In December, 1938, we obtained two ermines at Skykomish, King County, 18 miles west of Stevens Pass. These were in the brown winter coat. In that area the break between the brown and white winter coat seems to come just west of the main Cascade Summit, or at the same point that the break occurs between the brown and white winter coats of the long-tailed weasel.
Ermine skins have little value and usually bring from 10 to 35 cents. They are saved incidentally by trappers, for it takes but a few moments to skin and prepare them. They possess the strong, musk odor so typical of the long-tailed weasel.