Because the mountain beaver is closely related to the ground 
squirrels, Pfeiffer speculated that the mammary glands in the mountain 
beaver represent an expression of the latent capacity of the mammary 
epidermal tissue to produce special hairs associated with lactation, 
as is found in the monotremes, He further speculated that the production 
of mammary hairs by the mountain beaver may be a "physiological relict" 
that has been lost by the more advanced mammals including man. 
HABLTS 
Food 
The mountain beaver has a voracious appetite. It feeds on almost 
any available plant growing near its burrow. Scheffer (1929) stated 
that herbaceous plants are eaten whole, whereas woody plant structures 
are discarded after the bark has been pulled off for food, Bracken fern 
(Pteridium aquilinum), sword fern (Polystichum munitum), salal (Gaul- 
theria shallon), Oregon grape (Mahonia nervosa), and thimbleberry (Rubus 
parviflora) are some preferred foods, but willow (Salix), Douglas-fir 
(Pseudotsuga menziesii), western hemlock (Isuga heterophylla), other 
conifers, meadow grasses, and garden and truck crops are also eaten. In 
captivity, they are known to eat a wide variety of vegetables and fruits. 
Some plants known to be eaten by the mountain beaver are listed in 
appendix 2, 
Feeding 
Camp (1918) said that the mountain beaver has a slow and cumbersome 
gait and seldom ventures far from its burrow. He also said that in order 
for the animal to forage in a suitable clump of vegetation, it will dig 
a tungel directly into the area, and from its burrow entrance issue short 
trails to the vegetation to transport cut stems or fronds to the burrow 
entrances, Scheffer (1929) wrote that harvested cuttings varied in 
length from a few inches to several feet and are dragged to the burrow 
entrances or other safe retreat. The longer material is cut into smaller 
sections before being carried into the burrows to be eaten or stored. 
He stated that when dragging long shoots on a foraging trip the animal 
holds its head more or less to one side to avoid tramping on its load. 
Shorter pieces are lifted from the ground with the head well raised. 
Manner of Feeding 
Camp (1918) observed the manner of feeding of a captive mountain 
beaver, He wrote: 
"The rodent usually sits back upon its short tail, with the back 
curved, the hind feet extending out in front, soles forward, and 
the forepaws grasping 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 re- 
tained easily in one hand." (fig. 4) 
Stephens (1906) mentioned that the hind feet as well as the forefeet 
are used in grasping. 
15 
