Aplodontia rufa - (Rafinesque, 1817)
Mountain Beaver
Other English Common Names: Sewellel, mountain beaver
Taxonomic Status: Accepted
Related ITIS Name(s): Aplodontia rufa (Rafinesque, 1817) (TSN 180133)
French Common Names: castor de montagne
Unique Identifier: ELEMENT_GLOBAL.2.101780
Element Code: AMAFA01010
Informal Taxonomy: Animals, Vertebrates - Mammals - Rodents
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Mammalia Rodentia Aplodontiidae Aplodontia
Genus Size: A - Monotypic genus
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Concept Reference
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Concept Reference: Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.
Concept Reference Code: B93WIL01NAUS
Name Used in Concept Reference: Aplodontia rufa
Taxonomic Comments: This is the only species in this family. Helgen (in Wilson and Reeder 2005) applied the common name "sewellel" to this species. Inasmuch as this name is much less known than the traditional name (mountain beaver) and hinders effective communication, we retain the latter name for now.

Based on mitichondrial and nuclear DNA data, Piaggion et al. (2013) revised the subspecific taxonomy of A. rufa as follows. All populations north of the Columbia River belong to A. rufa olympica, which now includes the formerly recognized subspecies A. rufa ranieri and part of A. rufa rufa). Aplodontia rufa rufa occurs in Oregon (Cascades in northern Oregon, coastal region in southern Oregon) and extreme northwestern California. Aplodontia rufa pacifica occurs only in the coastal region of northwestern Oregon. The range of other nominal subspecies were not changed.
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 04Apr2016
Global Status Last Changed: 05Nov1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Except for two small relictual populations in California, the species is widespread in the Pacific Northwest, common, and not vulnerable to extinction.
Nation: United States
National Status: N5 (05Sep1996)
Nation: Canada
National Status: N4 (01Jan2018)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States California (SNR), Nevada (S1), Oregon (S4), Washington (S5)
Canada British Columbia (S4)

Other Statuses

Implied Status under the U.S. Endangered Species Act (USESA): PS
Comments on USESA: Subspecies nigra of northern California is listed by USFWS as Endangered.
Canadian Species at Risk Act (SARA) Schedule 1/Annexe 1 Status: SC (05Jun2003)
Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Special Concern (04May2012)
Comments on COSEWIC: The range of this species in Canada has contracted by 29% in the last 50 years and expansion into new habitat is constrained by large rivers. Within its range, habitat loss from urban development continues, and soil compaction caused by heavy machinery limits the use of otherwise suitable habitat. Climate change may further affect this species because it requires humid microclimates and low ambient temperatures. Rescue effect potential is limited by the short dispersal rates of the species and areas of unsuitable habitat along the border with the United States.
Designated Not at Risk in April 1984. Status re-examined and designated Special Concern in April 1999. Status re-examined and confirmed in November 2001 and May 2012.

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 20,000-2,500,000 square km (about 8000-1,000,000 square miles)
Range Extent Comments: Pacific coast of western North America, from southwestern British Columbia south to central California. From near Merritt, British Columbia, south along the Cascade, Olympic, Coast, and Siskiyou ranges to Rio Dell, California; Mt Shasta, California, southeastward through the Sierra Nevada of eastern California and west-central Nevada; Point Arena, Mendocino County, California; and near Pt. Reyes, Marin County, California (Carraway and Verts 1993).

Number of Occurrences: 81 to >300
Number of Occurrences Comments: Over a thousand EOs are known from throughout historic range.

Population Size: 10,000 to >1,000,000 individuals
Population Size Comments: While rare in some relictual populations in California, the species is common over much of the historic range.

Overall Threat Impact Comments: Common and considered a pest throughout much of range in coastal areas of Northern California, Oregon, Washington and southern British Columbia. Areas inhabitated are generally not visited frequently by humans.

Short-term Trend Comments: Probably stable. Status in Canada (southwestern British Columbia) not well known (Orchard, 1984 COSEWIC report).

Other NatureServe Conservation Status Information

Inventory Needs: Only needs are for relictual populations and these have been subjects of recent studies.

Protection Needs: Protect habitat from destruction by logging, burning, water diversion, and excessive livestock grazing.

Distribution
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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Pacific coast of western North America, from southwestern British Columbia south to central California. From near Merritt, British Columbia, south along the Cascade, Olympic, Coast, and Siskiyou ranges to Rio Dell, California; Mt Shasta, California, southeastward through the Sierra Nevada of eastern California and west-central Nevada; Point Arena, Mendocino County, California; and near Pt. Reyes, Marin County, California (Carraway and Verts 1993).

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: occurs (regularly, as a native taxon) in multiple nations

U.S. & Canada State/Province Distribution
United States CA, NV, OR, WA
Canada BC

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: Sechrest, 2002


U.S. Distribution by County Help
State County Name (FIPS Code)
CA Alpine (06003)*, Butte (06007), El Dorado (06017), Kern (06029)*, Lassen (06035)*, Madera (06039)*, Marin (06041)*, Mariposa (06043), Mendocino (06045), Mono (06051), Nevada (06057), Placer (06061), Plumas (06063), Shasta (06089), Sierra (06091), Siskiyou (06093)*, Tehama (06103), Tulare (06107), Tuolumne (06109)
NV Carson City (32510), Douglas (32005), Washoe (32031)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Lake Tahoe (16050101)+, Truckee (16050102)+, Upper Carson (16050201)+*, East Walker (16050301)+*
18 Big-Navarro-Garcia (18010108)+, Mccloud (18020004)+*, North Fork Feather (18020121)+, East Branch North Fork Feather (18020122)+, Middle Fork Feather (18020123)+, Upper Yuba (18020125)+, Upper Bear (18020126)+*, North Fork American (18020128)+, South Fork American (18020129)+, Thomes Creek-Sacramento River (18020156)+, Upper Kern (18030001)+, Upper Kaweah (18030007)+, Upper Merced (18040008)+, Upper Tuolumne (18040009)+, Upper Stanislaus (18040010)+, Tomales-Drake Bays (18050005)+*, Honey-Eagle Lakes (18080003)+*, Mono Lake (18090101)+, Crowley Lake (18090102)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A large, brown, terrestrial rodent; looks like a tailless muskrat.
Reproduction Comments: Low rate of reproduction. Monoestrous. Gestation lasts 28-30 days. One litter of 2-4 (usually 2-3) altricial young born March-April, sometimes as late as early May in north. Young are weaned in about 6-8 weeks. Females sexually mature in about 2 years; yearling females may ovulate but do not breed (see Carraway and Verts 1993). A few live up to 5-6 years.
Ecology Comments: Usually solitary but may live in loose colonies. Population density estimates generally range from 4 to 8 per hectare, but up to 15-20/ha (see Carraway and Verts 1993). Home range of 10 adult radiotracked for 3-19 months was 0.03-0.20 ha (mean 0.12 ha); moved up to 43 m from nest (see Carraway and Verts 1993). Significant predators include coyote and bobcat.
Habitat Type: Terrestrial
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Palustrine Habitat(s): Riparian
Terrestrial Habitat(s): Forest - Conifer, Forest - Mixed
Special Habitat Factors: Burrowing in or using soil
Habitat Comments: Forested areas from near sea level to timberline. Damp ravines and shaded hillsides in coastal and montane forests with an abundance of herbaceous ground cover. Typically in riparian habitat in moist coniferous forests. Most abundant near water courses in early to mid-seral stages vegetated by a tangle of second growth tree species, shrubs and forbs, and containing debris left from earlier forests (Carraway and Verts 1993). See Beier (1989) for information on habitat in the Sierra Nevada. Prefers damp soils; digs network of tunnels along stream banks. Tunnels generally are just below the ground surface, usually on north slopes in California, on south slopes in British Columbia. Primarily fossorial but can climb trees and swims well (but not arboreal or aquatic). Mostly underground in winter. Oval nests are constructed with leaves, twigs and grasses in a chamber that may be about 2 feet below the surface of the ground.
Adult Food Habits: Herbivore
Immature Food Habits: Herbivore
Food Comments: Feeds on a wide variety of vegetation; consumes ferns, forbs, and deciduous plants in summer; conifer foliage in fall/winter if other plants are unavailable (Banfield 1974). Forages mainly above ground (Epple et al. 1993). Requires free surface water or succulent vegetation on a daily basis. Caches grasses and forbs for winter food. Coprophagous.
Adult Phenology: Circadian, Crepuscular
Immature Phenology: Circadian, Crepuscular
Phenology Comments: Active during winter. Throughout the 24-hour day in summer, 5-7 periods of activity alternate with periods of rest. More active at night than during daylight hours.
Length: 47 centimeters
Weight: 1400 grams
Economic Attributes
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Economic Comments: May damage young conifers, garden vegetables, and berries. In the 1980s, it was estimated that 121,500 ha of reforestation units were affected (see Engeman et al. 1991). In the Sierra Nevada, damage to conifers is insignificant (see Todd 1992).
Management Summary
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Management Requirements: Methods used to control depredations by mountain beavers include removing food and cover plants mechanically, with herbicides, or with herbicides and fire; population reduction by use of toxic baits and trapping (number 0 or number 1 steel traps); and use of plastic mesh tubes surrounding tree seedlings (see Carraway and Verts 1993). Predator scents may be useful in controlling browsing damage (Epple et al. 1993).
Monitoring Requirements: See Engeman et al. (1991) for an evaluation of two activity indicators for use in burrow systems. Radio transmitters mounted in break-open collars have been used successfully (see Carraway and Verts 1993).
Biological Research Needs: Many aspects of biology have been studied, but more information on dispersal and demography is needed.
Population/Occurrence Delineation
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Use Class: Not applicable
Minimum Criteria for an Occurrence: Evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals in appropriate habitat where the species is presumed to be established and breeding.
Mapping Guidance: Where occurrence is fragmented into two or more pieces by unsuitable habitat that are less than 1 km apart, separate polygons should be drawn around each piece of occupied habitat.
Separation Barriers: Water bodies that cannot be traversed. No data available to determine width/current of such water bodies; subjective decisions must be made.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Very small home ranges: mean of 0.32 hectares for males (Lovejoy and Black 1979); up to 0.2 hectares, with a mean of 0.1 hectare (Martin 1971). As in most animals, dispersal likely is greater than a small home range might suggest. Limited data on this species indicates that dispersal extends at least several hundred meters (Martin 1971). The separation distance for suitable habitat is based on the likely low probability that two occupied locations separated by less than several kilometers of suitable habitat would represent independent populations.
Date: 21Sep2004
Author: Hammerson, G., and S. Cannings
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 30May1995
NatureServe Conservation Status Factors Author: Williams, Daniel F., and G. Hammerson
Element Ecology & Life History Edition Date: 30May1995
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • B.C. Ministry of Environment. Recovery Planning in BC. B.C. Minist. Environ. Victoria, BC. Available: http://www.env.gov.bc.ca/wld/recoveryplans/rcvry1.htm

  • Banfield, A. W. F. 1974. The mammals of Canada. University of Toronto Press, Toronto, Canada. 438 pp.

  • Beier, P. 1989. Use of habitat by mountain beaver in the Sierra Nevada, J. Wildl. Manage. 53:649-654.

  • Brooks, A. 1902. Mammals of the Chilliwack District. Ottawa Nat.15:239-244.

  • COSEWIC. 2012c. COSEWIC assessment and status report on the Mountain Beaver Aplodontia rufa in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xi + 30 pp.

  • Carraway, L. N., and B. J. Verts. 1993. Aplodontia rufa. Am. Soc. Mamm., Mammalian Species No. 431:1-10.

  • Carraway, L.N., and B.J. Verts. 1993. Aplodontia rufa. Am. Soc., Mammalian Species No. 431:1-10.

  • Committee on the Status of Endangered Wildlife in Canada (COSEWIC). 1999. Canadian Species at Risk: April 1999. Committee on the Status of Endangered Wildlife in Canada, Ottawa, Ontario, Canada. 17 pp.

  • Cosco, J. 1980. Mountain beaver (Aplodontia rufa): its biology and implications to forestry in British Columbia. B.S.F. Thesis, Faculty of For., Univ. B.C. 108pp.

  • Dalquest, W.W., and V.B. Scheffer. 1945. The systematic status of the races of the Mountain Beaver (Aplodontia rufa) in Washington. Murrelet 26:35-37.

  • Engeman, R. M., D. L. Campbell, and J. Evans. 1991. An evaluation of two activity indicators for use in mountain beaver burrow systems. Wildl. Soc. Bull. 19:413-416.

  • Environment Canada. 2015o. Management Plan for the Mountain Beaver (Aplodontia rufa) in Canada. Species at Risk Act Management Plan Series. Environment Canada, Ottawa. 3 pp. + Annex.

  • Epple, G., et al. 1993. Effects of predator odors on feeding in the mountain beaver (APLODONTIA RUFA). J. Mamm. 74:715-722.

  • Gyug, L.W. 2000. Status, distribution, and biology of the Mountain Beaver, Aplodontia rufa, in Canada. Can. Field-Nat. 114(3):476-490.

  • Hubbard, C.A. 1922. Some data upon the rodent Aplodontia. Murrelet 3:14-18.

  • Ingles, L. G. 1965. Mammals of the Pacific States. Stanford University Press, Stanford, California.

  • Jones, J. K., Jr., R. S. Hoffman, D. W. Rice, C. Jones, R. J. Baker, and M. D. Engstrom. 1992a. Revised checklist of North American mammals north of Mexico, 1991. Occasional Papers, The Museum, Texas Tech University, 146:1-23.

  • Lovejoy, B. P., and H. C. Black. 1979. Movements and home range of the Pacific mountain beaver APLODONTIA RUFA PACIFICA. American Midland Naturalist 101:393-402.

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

  • Martin, P. 1971. Movements and activities of the mountain beaver (APLODONTIA RUFA). Journal of Mammalogy 52:717-723.

  • Ministry of Environment. 2013. Management plan for the Mountain Beaver (Aplodontia rufa) in British Columbia. B.C. Ministry of Environment, Victoria, BC. 28 pp.

  • Nagorsen, D. W. 2005b. The rodents and lagomorphs of British Columbia. Royal B.C. Mus. Handb., Victoria, BC. (In press). 410pp.

  • Nagorsen, D.W. 2002. An identification manual to the small mammals of British Columbia. B.C. Minist. Sustainable Resour. Manage., and Minist. Water, Land and Air Prot., and Royal B.C. Mus., 153pp.

  • Pfeiffer, E.W. 1958. The reproductive cycle of the female mountain beaver. J. Mammal. 39:223-235.

  • Piaggio, A. J., B. A. Coghlan, A. E. Miscampbell, W. M. Arjo, D. B. Ransome, and C. E. Ritland. 2013. Molecular phylogeny of an ancient rodent family (Aplodontiidae). Journal of Mammalogy 94:529-543.

  • Ransome, D.B. 2003. Distribution, population dynamics, habitat associations, and the influence of forest management on mountain beavers. Project No. R2003-0123. Unpubl. rep. submitted to B.C. Forestry Innovation Investment. DBR Forestry-Wildl. Integrated Manage., Mission. 46pp.

  • Todd, P. A. 1992. Mountain beaver habitat use and management implications in Yosemite National Park. Natural Areas Journal 12:26-31.

  • Wilson, D. E., and D. M. Reeder (editors). 1993. Mammal species of the world: a taxonomic and geographic reference. Second edition. Smithsonian Institution Press, Washington, DC. xviii + 1206 pp. Available online at: http://www.nmnh.si.edu/msw/.

  • Wilson, D. E., and D. M. Reeder (editors). 2005. Mammal species of the world: a taxonomic and geographic reference. Third edition. The Johns Hopkins University Press, Baltimore. Two volumes. 2,142 pp. Available online at: http://vertebrates.si.edu/msw/mswcfapp/msw/index.cfm

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