1936] 



MAMMALS OF OREGON 



225 



Family APLODONTIIDAE : Mountain Bearers 

 APLODONTIA RUFA RUFA (RAFINESQUE) 



BBOWN MOUNTAIN BEAVER; MOUNTAIN BURBOWEBS; SEWELLEL (Indian name) ; 

 NETATE (Tolowa of Crescent City, Calif.) (C. H. M.) 



Anisonyss f rufa Rafinesque, Amer. Monthly Mag. 2: 45, 1817. 



Type region. Neighborhood of the Columbia River, Oreg. Restricted to the 

 Mount Hood section. Original description based on Lewis and Clark, from 

 skins obtained from the Indians. 



General characters. Size about the same as a very large muskrat (pi. 36) ; 

 form heavy compact; legs, tail, and ears short; eyes small; feet large with 

 wholly naked soles and strong claws; mustaches long and bristly; fur short 

 and dense, with short, coarse, shiny guard hairs ; upper parts dark rusty brown 

 with dusky nose and ears and a small white spot at anterior base of each ear ; 

 lower parts clear buffy brown with conspicuous dark brown nipple spots in the 

 females. 



Measurements. Old female from Marmot, west of Mount Hood : Total length, 

 330 mm ; tail, 34 ; foot, 55 ; ear in dry specimens, 16. Weight about 2 pounds. 



Distribution and habitat. This large form of the mountain beaver 

 extends along the lower slopes of the Cascade Range from southern 

 British Columbia to 

 northwestern California 

 (fig. 51). In Oregon 

 there are specimens from 

 Marmot, Bissel, Eagle 

 Creek, V i d a , McKenzie 

 Bridge, Mount Mazama. 

 Anna Creek, Fort Kla- 

 math, Siskiyou, and north 

 base of Ashland Peak. 

 There are also records of 

 their occurrence at Hood 

 River, west base of Mount 

 Jefferson, west base of 

 Three Sisters, 20 miles 

 east of Drew, near head 

 of Rogue River, and at 

 base of Mount McLough- 

 lin (Pitt). Generally they are in Transition Zone timber country in 

 the gulches and ravines, where there is considerable moisture and 

 dense growth of vegetation. Their range is irregular, interrupted, 

 and to some extent colonial. Locally they are often abundant, but 

 they occupy only a small part of the range assigned to them. 



General habits. In many ways the habits and actions of mountain 

 beavers suggest pocket gophers, as does also their general appear- 

 ance, for if the big camas pocket gopher (Thomomys bidbi- 

 vorm) were twice its present si/e its longer tail would be the only 

 convenient means of distinguishing the two. The burrowing habits 

 and similar mode of life are evidently responsible for this superficial 

 resemblance. Mountain borrowers would have been a better name 

 for Aplodontia and especially for this mountain-dwelling species. 

 The animals are almost never seen except when caught in traps, but 



' 7209 36 15 



FIGURE 51. Range of the two forms of the moun- 

 tain beaver in Oregon : 1, Aplodontia rufa, rufa; 

 Type I 



2, A. r. pad flea. 



localities circled. 



