beneath the snow during the winter. Scheffer (1929) affirmed that it 
is active during the winter, at least at the lower altitudes where it 
was commonly observed. He wrote: 
"Under a snow covering of a foot or more they will burrow 
extensively, usually though not always, working so close 
to the ground as to leave a trail or path scratched in the 
soil, Sometimes the snow burrows lead to the surface, 
especially near logs or stumps, and the animals come out 
and travel about on the crust. This is indicated by tracks 
and by the marks of girdling and gnawing on the bark of 
shrubs and young trees. They also have been observed 
wandering about at evening twilight on the snow crust of 
open fields." 
Dalquest (1948) said that the animal is more restricted in habits in 
the winter, and is rarely seen during the day. He mentioned that the 
spring revealed elongated earth cores, about 6 to 8 inches in diameter and 
2 to 4 feet long, as evidence of mountain beaver activity under the snow. 
ENEMIES 
Predators 
The mountain beaver is a source of food among some predators. Lord 
(1866) regarded the raccoon (Procyon lotor) as a possible enemy of the 
mountain beaver, Anthony (1916) speculated that, owing to the dense 
cover of vegetation, the animal was not very extensively preyed upon by 
hawks and owls. Scheffer (1929) thought that certain predaceous birds 
and mammals were not abundant enough to take a toll of the mountain beaver, 
Pfeiffer (1953) caught five weasels (Mustela frenata) and one mink 
(Must#la vison) while trapping for mountain beaver in southern British 
Columbia, He believed that the weasels were hunting for mountain beaver 
kits, and doubted that any weasel, excepting mink, could kill an adult 
mountain beaver. Taylor and Shaw (1927) recorded that the mountain lion 
(Felis concolor) occasionally preyed on the mountain beaver in Washington. 
Young (1958) reported that the bobcat (Lynx rufus) preyed on the rodent 
in spring and summer. 

Other predators that have been cited are coyotes (Canis latrans), 
gray foxes (Urocyon cinereoargenteus), badgers (Taxidea taxus), and 
fishers (Martes pennanti). 
Parasites 
The mountain beaver has its share of parasites. Victor B. Scheffer 
(personal communication) reported three species of fleas from a mountain 
beaver which Dr. William L. Jellison described for him, These included 
28 Dolichopsyllus stylosus, 1 Hystrichopsylla sp., and 1 Trichopsylloides 
oregonensis. Information on other parasites reported is listed in 
appendix 3. 
21 
