Species and Plant Community
Accounts for Identified Wildlife

Table of contents

Mammals - Rodents

MOUNTAIN BEAVER (Aplodontia rufa rufa - Aplodontia rufa rainieri)

Status

Two subspecies of mountain beaver occur in B.C. Aplodontia rufa rainieri is BLUE-listed due to its small population size, and A. r. rufa is RED-listed, primarily due to loss of habitat to urban development.

Ecology

The mountain beaver inhabits wet, densely vegetated areas. It excavates and lives in burrow systems where soil is moderately firm. The species is not considered gregarious, but may attain high densities locally where suitable vegetation and soil conditions occur. It may range to elevations of 2200 m, but is more common in humid, vegetated areas at lower elevations. The mountain beaver is primarily nocturnal, and most activity is restricted to within approximately 25 m of their burrow; home ranges are therefore relatively small, varying in size from 0.03-0.2 hectares. Dispersal movements of approximately 200 m have been recorded for one male, and 570 m for one female. The mountain beaver is strictly herbivorous, feeding on a variety of plants. Succulent species such as swordfern (Polystichum munitum) and bracken fern (Pteridium aquilinum) may be heavily used where present, but are not required at all sites. Mountain beavers will feed on grasses and conifers on occasion.

Distribution


Aplodontia rufa rufa
is found south of the Fraser River, approximately from Hope west to Aldergrove-Langley. Aplodontia rufa rainieri is found in higher forested areas to the east of Hope, in the Cascade Mountains. The exact geographic delineation between the two subspecies is not known. No confirmed records exist north or northwest of the lower Fraser River.

Ecoprovinces: Ecosections

Biogeoclimatic units


Habitat requirements

Broad ecosystem units

Structural stage

All, but in forested areas mountain beaver are usually associated with clearings (e.g., openings associated with overstorey mortality, stream courses and springs within stands) or with the more open forest types typical of hygric or subhygric sites.

Critical habitats and habitat features

Limits to the natural distribution of the mountain beaver are associated with rainfall and edaphic conditions that promote succulent vegetation and high humidity within burrows. Succulent vegetation is important because the species is limited in its ability to concentrate urine, and cool, humid burrows are important to accomodate the species poor thermoregulatory capabilities. In B.C., most mountain beaver occurrences have been found in areas with water (either above or underground), well developed, firm soils, and an abundance of vegetation. If free-standing water is lacking, succulent vegetation must be present.

Selected references

Cosco, J. 1980. Mountain beaver (Aplodontia rufa): Its biology and implications to
forestry in British Columbia. Univ. B.C., Fac. For. B.S.F. thesis.

Feldhamer, G.A. and J.A. Rochelle. 1982. Mountain beaver. In Wild ammals of North
America: Biology, management and economics. J.A. Chapman and G.A. Feldhamer (eds.). Johns Hopkins Univ. Press, Baltimore, MD. pp. 167-175.

Johnson, S.R. 1971. The thermal regulation, microclimate, and distribution of the
mountain beaver, Aplodontia rufa pacifica Merriam. Oreg. State Univ., Corvallis, OR. PhD thesis.

Martin, P. 1971. Movements and activities of the mountain beaver (Aplodontia rufa).
J. Mammal. 52(4):717-723.

Motubo, D. 1978. Effects of controlled slash burning on the mountain beaver
(Aplodontia rufa rufa). Northwest Sci. 52(2):92-99.

Voth, E.H. 1968. Food habits of the Pacific mountain beaver, Aplodontia rufa
pacifica Merriam. Oreg. State Univ., Corvallis, OR. PhD thesis.


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