BLACK-FOOTED FERRET
Mustela nigripes
The entrances to the burrows are usually under logs, roots, or rocks, or the den may be in a hollow log, stump or base of a tree, or even under a cabin in the woods. The burrows in the ground are commonly a series of tunnels some yards in length, with an oval nest and storage chamber two or three feet underground, and with branches from the main passageway. The nest chamber, a foot or more in diameter, is filled with fragments of dry leaves and other soft vegetable material. One chamber is usually used for sanitary purposes. The used entrance hole is commonly without a sign of dug earth about it, the loose soil from the burrow and its chambers apparently having been thrown out at another opening, which appears to be used for this purpose only and is kept plugged with earth.
Throughout most of the northern half of its range these chipmunks usually hibernate from some time in October until March. Their hibernation is far less profound than that of the woodchuck and they not infrequently appear above ground during periods of mild weather, even in midwinter. The hibernating period is shorter in the southern part of the range.
They vary much in numbers from year to year and at times appear to increase suddenly in localities where food is plentiful, indicating a probable food migration. The young, numbering from four to six in a litter, are born at varying times between the last of April and late summer, indicating the possibility of more than one litter a season.
The most characteristic note of this chipmunk is a throaty chuck, chuck, which is ordinarily used as a call note, but which in spring is uttered many times in rapid succession to express the seasonal feeling of joy and well being, thus taking on the character of a song. Such joyful notes may be heard on every hand in places where the little songsters are numerous. In addition, they have a high-pitched, chirping note and a small churring whistle when much alarmed.
THE OREGON CHIPMUNK (Eutamias townsendi and its relatives)
(For illustration, [see page 543])
The resident species of birds and mammals in the humid coastal region of Oregon, Washington, and southern British Columbia are strikingly characterized by their darker and browner colors in comparison with closely related species in more arid districts.