Martes caurina [Merriam]
Western marten
Description.—The marten is slightly smaller and slimmer than a house cat, and at first glance resembles a large squirrel. The legs are longer, the body stouter and the fur more fluffy than those of a mink or weasel. Adult males weigh from two to two and a half pounds, and females from one and a half to two pounds. Males are slightly more than two feet in total length and females about 18 inches, the tail comprising one-third or more of the total length. The head is broad and narrows rapidly to a sharp muzzle. The ears are large, erect and prominent. The feet are large with stout toes and long, sharply curved pinkish-white claws. The body and head are rich golden brown, the tail, wrists, feet and muzzle being darker.
The western marten ranges from British Columbia southward through Idaho and Washington to California. A closely related species, americana, is found in Alaska, the eastern United States and Canada. Martens and fishers may be distinguished from weasels and minks by the presence of 18 rather than 16 teeth in the upper jaw and 20 instead of 18 teeth in the lower jaw.
The western marten is arboreal. Its principal habitat in Washington is the Canadian Life-zone forests of the Olympic, Cascade and Blue mountains and the various ranges in the northeastern part of the state. At one time it ranged near sea level along the densely forested coastal belt and may still do so in the more rugged parts of the Willapa Hills.
The marten is both diurnal and nocturnal. In Mount Rainier National Park the species has become quite tame and may be seen in the daytime. Many of the small mammals upon which it feeds are diurnal, but others are nocturnal. The marten is active throughout the year. Trappers report that during a storm the marten "holes up in rock slides" where it lives on conies and chipmunks until the storm passes. It spends a large part of its time in trees, and travels through them for long distances. It climbs more skillfully than the tree squirrels upon which it feeds. On the ground or on snow the marten travels in bounds, a yard at a leap, and its characteristic bounding gait forms tracks that are distinctive and easily followed.
Mammals of the weasel family mostly are not gregarious but the marten is exceptional in that in the winter it travels in bands of 6 to 10 animals. Individuals composing these bands are inclined to wander but nevertheless the whole band travels in a definite general direction at a good rate of speed. Travel-ways or "runs" may be used by more than one band, and a run may extend for many miles, perhaps for as many as 50. A band of martens may take two weeks to complete the circuit, but usually returns to the starting point in less than a week. Most runs are about "half-way up the mountain," or midway between the crest of the hill or timber-line and the floor of the stream valley below. In summer the marten ranges higher; it lives in the trees just below timber-line and in the talus slides near timber-line. When the snows are unusually late the martens may keep to these higher areas until November.
The food of the marten consists principally of small mammals and probably birds; the staple food in winter is the Douglas squirrel. In summer they feed on pikas, mantled ground squirrels and chipmunks. Mice, also, are eaten. The deer mouse, Peromyscus maniculatus, is usually abundant about old cabins and is successfully used as bait by trappers. Wood rats and flying squirrels are also eaten, the latter being especially important in certain areas. The tracks of martens that had been following snowshoe rabbits were seen on several occasions but the martens had turned off before a kill was made. In every instance the rabbit tracks indicated that the animals were hopping leisurely and browsing; apparently the tracks were made some time before the marten began to follow them.
Martens are inquisitive, and to judge from their tracks in snow they investigate almost every object that they pass; a fallen mound of snow, branch, bit of moss, log or isolated tree is apt to be visited. Failing to find a meal in or around one of these objects, the marten visits the next object that catches its eye. Seemingly the animal always is giving concentrated attention to some definite object although the attention can shift in an instant when a more interesting object comes in to view. As a result the trail of a marten in the snow is an intricate affair composed of numerous straight lines and sharp turns.
The trapping of martens is specialized work, engaged in by professional trappers that follow trap lines many miles in length. Trappers commonly have a base cabin and one or two shelters situated a day's march apart, The trap-line is set in a circle, requiring one to three days' travel by the trapper to complete the circuit.