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Sorex trowbridgii

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA EULIPOTYPHLA SORICIDAE

Scientific Name: Sorex trowbridgii
Species Authority: Baird, 1857
Common Name(s):
English Trowbridge's Shrew

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): NatureServe (Hammerson, G.)
Reviewer(s): Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global Mammal Assessment Team)
Justification:
Listed as Least Concern because it is widespread, there are no major threats, and its population is not currently in decline.
History:
1996 Lower Risk/least concern (Baillie and Groombridge 1996)

Geographic Range [top]

Range Description: This species is found in 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 in the United States (George 1989). It occurs from sea level up to 1,820 m asl.
Countries:
Native:
Canada (British Columbia); United States (California, Oregon, Washington)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is widely distributed, it is often the most abundant (or at least the most commonly captured) shrew where it occurs (Verts and Carraway 1998).
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: It is found in mature forest (dry or moist) with abundant ground litter; forested canyons and ravines, and swampy woods; deep rank grass near salmonberry thickets (Destruction 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).

Maximum life-span is estimated at about 18 months. Populations decline after forest wildfires. Fall population tends to be about double the spring population (George 1989). Pregnant females have been recorded from March-May in Washington; with three to four embryos. It breeds in February-early June in Sierra Nevada; with an average of five embryos; post-partum pregnancy is probably common. Average of 3.9 embryos in Oregon. The age of sexual maturity is less in areas with a warmer climate. This shrew is primarily insectivorous, and also feeds on spiders, worms, and centipedes. It feeds on more vegetable matter than other shrews in this genus (Banfield 1974). It is known to feed on the seeds of Douglas-fir, pine, and other plants, especially in winter. It is active throughout the year.
Systems: Terrestrial

Threats [top]

Major Threat(s): There are no documented threats to this species. 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).

Conservation Actions [top]

Conservation Actions: It occurs in protected areas throughout its range.

Citation: NatureServe (Hammerson, G.) 2008. Sorex trowbridgii. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 03 September 2014.
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