530 University of California Publications in Zoology  {Vou.17 
the stem, root or leaf. The short first finger is used like a human 
thumb and the large callosities on the palms aid in holding an object 
so firmly that it can be retained easily in one hand. Stephens (1906, 
p- 95) says that the hind feet as well as the fore feet are used in 
erasping. Plants are harvested in sections from two to six inches in 
length so that they can be dragged into the burrows. Tough woody 
twigs and stems are chewed through from one side only, not in the 
manner in which beavers attack large trees. If the plant is a soft 
annual the whole stem is rapidly nibbled; if a perennial, the bark is 
chewed off in the manner of a beaver or porcupine and the wood 
discarded. 
More than one writer since Lewis and Clark have mentioned the 
climbing habit of mountain beavers; and the evidence seems to be 
good that at least the Oregon and Washington coast species climb into 
low bushes for food (see Lum, 1878, pp. 10-13). The mountain 
beavers on the grounds of the University of Washington at Seattle 
have been seen climbing. 
HIBERNATION 
There seems to be no certain evidence that the mountain beaver 
hibernates even in the coldest part of its range. Cooper (1860, p. 82) 
affirms that these animals had been seen running over the snow in 
the Nisqually Valley, Washington. Suckley (in Suckley and Gibbs, 
1860, p. 124) learned from the Nisqually Indians that the mountain 
beaver moves about a little during the winter but does *‘ 
decidedly active till late in the spring.’’ Lord (1866, pp. 346-358) 
maintains that the animal only partially hibernates—this of the 
species in British Columbia. Matteson (1877, pp. 434-435) believes 
that the mountain beaver hibernates, at that time covering the 
entrance of the burrow with stalks of leaves and fern. Bretherton 
(1895, p. 124) says that they do not hibernate. 
Lum (1878, pp. 10-13) reports the following of the Oregon and 
Washington species: ‘‘They do not hibernate, but keep their burrows 
open all winter; beaten trails in the snow are often seen, leading 
not become 
above ground for a few feet from one hole to another. They are able 
to gather their food at any time of the year, seldom going more than 
a few feet from the entrance of their holes to procure it.”’ Brooks 
(1899, p. 259) asserts that the aplodontia in British Columbia ‘‘does 
not hibernate at lower levels but must do so on the higher mountains, 
as it does not seem to make ‘hay’ like the Pika.’’ 
