Sorex trowbridgii - Baird, 1858
Trowbridge's Shrew
Other English Common Names: Trowbridge's shrew
Taxonomic Status: Accepted
Related ITIS Name(s): Sorex trowbridgii Baird, 1857 (TSN 179956)
French Common Names: musaraigne de Trowbridge
Unique Identifier: ELEMENT_GLOBAL.2.103809
Element Code: AMABA01220
Informal Taxonomy: Animals, Vertebrates - Mammals - Other Mammals
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Mammalia Soricomorpha Soricidae Sorex
Genus Size: D - Medium to large genus (21+ species)
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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: Sorex trowbridgii
Taxonomic Comments: See George (1988) for electrophoretic study of systematic relationships among SOREX species.
Conservation Status
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NatureServe Status

Global Status: G5
Global Status Last Reviewed: 05Apr2016
Global Status Last Changed: 01Nov1996
Ranking Methodology Used: Ranked by inspection
Rounded Global Status: G5 - Secure
Reasons: Widely distributed in a variety of habitats; often the most abundant shrew where it occurs.
Nation: United States
National Status: N5 (05Sep1996)
Nation: Canada
National Status: N3 (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 (S2), Oregon (S4), Washington (S5)
Canada British Columbia (S3)

Other Statuses

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: Coastal southwestern British Columbia south of Burrard Inlet south through western Washington and Oregon to northwestern California, south through coast ranges to Santa Barbara County, east to Warner Mountains (northeastern California), south through Sierra Nevada to Kern County, California (George 1989). Sea level to 1820 m.

Population Size: >1,000,000 individuals
Population Size Comments: Often the most abundant (or at least most commonly captured) shrew where it occurs (Verts and Carraway 1998).

Overall Threat Impact Comments: No documented threats. One study showed a decline following logging, but another showed an increase, indicating that dominant vegetation structure may not be responsible for regulating abundance (Verts and Carraway 1998).

Short-term Trend Comments: No information.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Coastal southwestern British Columbia south of Burrard Inlet south through western Washington and Oregon to northwestern California, south through coast ranges to Santa Barbara County, east to Warner Mountains (northeastern California), south through Sierra Nevada to Kern County, California (George 1989). Sea level to 1820 m.

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)
NV Douglas (32005)*, Washoe (32031)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
16 Smoke Creek Desert (16040203)+, Lake Tahoe (16050101)+*, Truckee (16050102)+
17 Warner Lakes (17120007)+*
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Diagnostic Characteristics: See Carraway (1995) for a key to western North American soricids based primarily on dentaries.
Reproduction Comments: Pregnant females recorded March-May in Washington; 3-4 embryos. Breeds February-early June in Sierra Nevada; average of 5 embryos; post-partum pregnancy probably common. Average of 3.9 embryos in Oregon. Age of sexual maturity less in areas with warmer climate.
Ecology Comments: Maximum life-span estimated at about 18 months. Populations decline after forest wildfires. Fall population tends to be about double spring population (George 1989).
Non-Migrant: Y
Locally Migrant: N
Long Distance Migrant: N
Palustrine Habitat(s): Riparian
Terrestrial Habitat(s): Forest - Conifer, Forest - Mixed
Special Habitat Factors: Fallen log/debris
Habitat Comments: Mature forest (dry or moist) with abundant ground litter; forested canyons and ravines, and swampy woods; deep rank grass near salmonberry thickets (Destructioin Island off Washington); riparian fringe areas (but not streamside); under chaparral (at southern edge of range); cut forest if sufficient ground cover present (George, in Wilson and Ruff 1999; George 1989).
Adult Food Habits: Invertivore
Immature Food Habits: Invertivore
Food Comments: Primarily insectivorous, also feeds on spiders, worms, and centipedes. Feeds on more vegetable matter than other shrews in this genus (Banfield 1974). Known to feed on seeds of Douglas-fir, pine, and other plants, especially in winter.
Adult Phenology: Circadian
Immature Phenology: Circadian
Phenology Comments: Active throughout the year.
Length: 13 centimeters
Weight: 9 grams
Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation
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Group Name: Shrews

Use Class: Not applicable
Minimum Criteria for an Occurrence: An area of suitable habitat where there is evidence of presence (or historical presence), with potential for continued presence; evidence minimally including a specimen or, in the case of certain species, a determination by a reliable observer of a live specimen in the hand.
Separation Barriers: Arbitrarily set at rivers wider than 50 meters at low water. Some shrews are relatively strong, active swimmers (notably SOREX PALUSTRIS, S. BENDIRII, SOREX ALASKANUS). No data on dispersal or other movement across water barriers.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Dispersal distances of shrews are poorly known, but these mammals are mobile enough to cover fairly large distances. Mature males especially may wander widely (Hawes 1977). Separation distance for suitable habitat attempts to reflect the small home range size of shrews, their secretive habits and consequent apparent absence in areas where they do in fact occur, and the seemingly low probability that two occupied locations separated by a gap of less than several kilometers of suitable habitat would represent independent populations.

Home ranges small: for breeding SOREX VAGRANS in British Columbia, 338 - 5261 square meters (Hawes 1977); in California, mean of about 372 square meters (Ingles 1961); for breeding S. MONTICOLUS (=OBSCURUS) in British Columbia, mean of 4020 square meters (Hawes 1977); for S. ARANEUS in England, a fall and winter home range of about 2800 square meters, with females occupying exclusive ranges (Buckner 1969).

Date: 21Sep2004
Author: Cannings, S., and G. Hammerson
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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Element Ecology & Life History Edition Date: 08Dec1989

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

  • Bradley, R.D., L.K. Ammerman, R.J. Baker, L.C. Bradley, J.A. Cook. R.C. Dowler, C. Jones, D.J. Schmidly, F.B. Stangl Jr., R.A. Van den Bussche and B. Würsig. 2014. Revised checklist of North American mammals north of Mexico, 2014. Museum of Texas Tech University Occasional Papers 327:1-28. Available at: http://www.nsrl.ttu.edu/publications/opapers/ops/OP327.pdf

  • British Columbia Conservation Data Centre. 1998. Unpubl. files. B.C. Minist. Environ., Lands and Parks, Resour. Inventory Branch, Victoria, BC.

  • Buckner, C. H. 1969. Some aspects of the population ecology of the common shrew, Sorex araneus, near Oxford, England. Journal of Mammalogy 50:326-332.

  • Carraway, L. N. 1995. A key to Recent Soricidae of the western United States and Canada based primarily on dentaries. Occasional Papers of the Natural History Museum, University of Kansas (175):1-49.

  • Churchfield, S. 1992. The Natural History of Shrews. Cornell University Press, Ithaca, New York. 192 pp.

  • George, S. B. 1988. Systematics, historical biogeography, and evolution of the genus Sorex. J. Mammalogy 69:443-461.

  • George, S. B. 1989. SOREX TROWBRIDGII. Am. Soc. Mamm., Mammalian Species No. 337:1-5.

  • Hawes, M. L. 1977. Home range, territoriality and ecological separation in sympatric shrews, Sorex vagrans and Sorex obscurus. Journal of Mammalogy. 58:354-367.

  • Ingles, L. G. 1961. Home range and habitats of the wandering shrew. Journal of Mammalogy 42:455-462.

  • Jackson, H. H. 1961. Mammals of Wisconsin. University of Wisconsin Press, Madison. 504 pp.

  • Jackson, H.H. 1928. A taxonomic review of the North Americanlong tailed shrews (genera Sorex and Microsorex). N. Amer. Fauna. 51:1-238.

  • Nagorsen, D. 1990. The mammals of British Columbia: a taxonomic catalogue. Mem. No. 4. Royal B.C. Mus., Victoria. 140pp.

  • Nagorsen, D.W. 1996. Opossums, Shrews and Moles of British Columbia. Royal B.C. Mus. Victoria, BC. 169pp.

  • Verts, B. J., and L. N. Carraway. 1998. Land mammals of Oregon. University of California Press, Berkeley. xvi + 668 pp.

  • 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/.

  • Zuleta, G.A., and C. Galindo-Leal. 1993. Distribution and abundance of small mammals at risk in a fragmented landscape. Unpubl. rep. for B.C. Minist. Environ., Lands and Parks, Wildl. Branch, Victoria. 34pp.

  • Zuleta, G.A., and C. Galindo-Leal. 1994. Distribution and abundance of four species of small mammals at risk in a fragmented landscape. B.C. Minist. Environ., Lands and Parks, Wildl. Branch. Working Rep. WR-64. Victoria, British Columbia. 80pp.

  • van Zyll de Jong, C.G. 1983. Handbook of Canadian mammals. 1. Marsupials and insectivores. National Museum of Natural Sciences, National Museums of Canada, Ottawa, Canada. 210 pp.

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