Species Profile

Pacific Water Shrew

Scientific Name: Sorex bendirii
Taxonomy Group: Mammals
COSEWIC Range: British Columbia
COSEWIC Assessment Date and Status Change: April 2016
COSEWIC Status: Endangered
COSEWIC Status Criteria: B2ab(iii,iv)
COSEWIC Reason for Designation: This shrew is restricted to British Columbia’s Lower Mainland and adjacent low valleys. It is rare there, associated with freshwater streams and adjacent wet habitats. Urban development, agriculture, and forestry have reduced the amount and quality of habitat. There is an inferred and projected ongoing decline in habitat and subpopulations in much of its range in Canada.
COSEWIC History of Status Designation: Designated Threatened in April 1994 and in May 2000. Status re-examined and designated Endangered in April 2006. Status re-examined and confirmed in April 2016.
SARA Status: Schedule 1, Endangered
Date of Listing (yyyy-mm-dd): 2003-06-05

Please note that this information is provided for general information purposes only. For the most up to date and accurate list of species listed under the Species at Risk Act, please see the Justice Laws Website.

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Quick Links: | Photo | Description | Distribution and Population | Habitat | Biology | Threats | Protection | Recovery Initiatives | Recovery Team | National Recovery Program | Documents

Image of Pacific Water Shrew

Pacific Water Shrew Photo 1

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Description

With its small ears, long, pointed snout, and long, slender tail, the Pacific Water Shrew resembles a mouse. It measures 154 mm from the tip of its snout to the end of its tail, and it weighs on average 10.6 g; it is the largest shrew in North America. Its pelage ranges from dark brown to black, with the undersides being slightly lighter. Its long tail is a uniform dark brown. The Pacific Water Shrew has several adaptations for an aquatic lifestyle. For example, its hind feet have a stiff fringe of hairs of up to 1 mm in length that helps it to swim.   This species can be confused with the common water shrew, which can be distinguished by its light to black dorsal fur, its silver grey belly, and its two-toned tail, which has a paler underside. (Updated 2017/02/20)

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Distribution and Population

The Pacific Water Shrew is found only in western North America, on the Pacific coastal lowlands from northern California through western Oregon and Washington to southwestern British Columbia. In Canada, the species is confined to the lower Fraser River valley region in extreme southwestern British Columbia. It ranges as far east as the Chilliwack River and Harrison Lake. The 142 known occurrence records (sightings and captures) are from about 44 distinct sites. Of the 142 records, 99 are historical museum specimens collected between 1888 and 1957.   There are no estimates of Canadian population sizes or long-term trends. The species appears to be rare throughout its range. (Updated 2017/02/20)

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Habitat

The Pacific Water Shrew is generally found in riparian and wetland habitats. This species is associated with skunk cabbage marshes, red alder riparian habitat, and dense, wet forests of western red cedar. Most captures are in riparian habitats in close proximity to water. However, individuals have been captured in forests 25 to 350 m from a stream. Although forested habitats are important, in British Columbia the species has been found in non-forested grassy habitats bordering ditches and sloughs.   There are no specific data on habitat trends for this species. However, there has been a loss of wetlands and forests since the early 1900s. (Updated 2017/02/20)

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Biology

Little information is available on the biology of this species except for its diet. Primarily insectivorous, this mammal feeds mainly on insect larvae, slugs, snails, mayfly nymphs and earthworms. Approximately 25% of its prey is aquatic. This semi-aquatic shrew can swim continuously for up to 3.5 minutes and dive for up to 60 seconds. Air trapped under the fur provides buoyancy and possibly insulation while it is in the water. In Oregon, the breeding period extends from February to August, and females produce two to three litters of five to seven young each. The maximum lifespan is thought to be about 18 months. Owls, domestic cats, fish, and Pacific giant salamanders are thought to be the shrew’s predators. (Updated 2017/02/20)

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Threats

The main threat to the Pacific Water Shrew is habitat loss and fragmentation. Agriculture and forest harvesting activities have an impact on this species, but development probably poses the greatest threat. In Canada, the Pacific Water Shrew’s distribution coincides with a heavily urbanized area undergoing rapid development and habitat change. In 2004, the combined population of the Greater Vancouver Regional District and the Fraser Valley Regional District was about 2.4 million, an increase of about 11% since 1996.   Housing, commercial, industrial and recreational (e.g., golf course) development reduces forested areas and riparian habitats that border streams or wetlands; the habitat is also degraded by run-off and storm water management.   The rarity of this species, coupled with its restriction to riparian and wetland habitats, make it susceptible to habitat loss, fragmentation and degradation.   Changes in water quality resulting from contaminants could affect the aquatic invertebrates that are eaten by the Pacific Water Shrew. Contaminants such as oil would be expected to reduce the insular efficiency of its pelage. (Updated 2017/02/20)

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Protection

Federal Protection

The Pacific Water Shrew is protected under the federal Species at Risk Act (SARA). More information about SARA, including how it protects individual species, is available in the Species at Risk Act: A Guide.

Provincial and Territorial Protection

To know if this species is protected by provincial or territorial laws, consult the provinces' and territories' websites.

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Recovery Initiatives

Status of Recovery Planning

Recovery Strategies :

Name Recovery Strategy for the Pacific Water Shrew (Sorex bendirii) in Canada
Status Final posting on SAR registry

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Recovery Team

Pacific Water Shrew Recovery Team

  • Kym Welstead - Chair/Contact - Government of BC
    Phone: 604-582-5279  Fax: 604-930-7119  Send Email

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Documents

PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.

18 record(s) found.

COSEWIC Status Reports

  • COSEWIC assessment and update status report on the Pacific water shrew Sorex bendirii in Canada (2006-08-30)

    The Pacific water shrew is the largest North American species of Sorex with a total length of 154 mm and a body mass of 10.6 g. The dorsal pelage ranges from dark brown to black; the undersides are dark brown. The tail is a unicoloured dark brown. The large hind feet have a stiff fringe of hairs up to 1 mm in length.
  • COSEWIC Status Appraisal Summary on the Pacific Water Shrew Sorex bendirii in Canada (2017-01-23)

    This shrew is restricted to British Columbia’s Lower Mainland and adjacent low valleys. It is rare there, associated with freshwater streams and adjacent wet habitats. Urban development, agriculture, and forestry have reduced the amount and quality of habitat. There is an inferred and projected ongoing decline in habitat and subpopulations in much of its range in Canada.

Response Statements

  • Response Statement - Pacific Water Shrew (2017-01-11)

    This shrew is restricted to British Columbia’s Lower Mainland and adjacent low valleys. It is rare there, associated with freshwater streams and adjacent wet habitats. Urban development, agriculture, and forestry have reduced the amount and quality of habitat. There is an inferred and projected ongoing decline in habitat and subpopulations in much of its range in Canada.
  • Response Statements - Pacific Water Shrew (2006-11-29)

    The habitat of this rare species, confined to the lower Fraser valley region of British Columbia, continues to decline and fragment as a result of development. There is little chance of rescue. It is extremely rare throughout its range.

Recovery Strategies

  • Recovery Strategy for the Pacific Water Shrew (Sorex bendirii) in Canada (2014-12-10)

    The Pacific Water Shrew, Sorex bendirii, is a semiaquatic riparian habitat specialist whose range in Canada is limited to approximately 5700 km2 in the highly urbanized landscape of the Lower Mainland/Fraser Valley of British Columbia (B.C.). This mammal was designated as Endangered by COSEWIC in 2006. Increasing urbanization and associated effects such as road-building and pollution, forestry on Crown land, and agricultural activities are reducing the amount of suitable habitat available for the Pacific Water Shrew. Habitat loss, degradation, and fragmentation from urban development, forestry, and agriculture are the primary threats to the species in Canada. Additional potential threats include aquatic pollution, mortality due to domestic cats, research mortality, and flooding.

Orders

  • Order Acknowledging Receipt of the Assessments Done Pursuant to Subsection 23(1) of the Act (2007) (2007-05-16)

    This Order acknowledges receipt by the Governor in Council of the assessments of the status of 40 species done pursuant to paragraph 15(1)(a) and in accordance with subsection 23(1) of the Species at Risk Act (SARA) by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). The purpose of SARA is to prevent wildlife species from being extirpated or becoming extinct, to provide for the recovery of wildlife species that are extirpated, endangered or threatened as a result of human activity and to manage species of special concern to prevent them from becoming endangered or threatened.
  • Order Amending Schedule 1 to the Species at Risk Act (volume 141, number 26, December 13, 2007) (2007-12-26)

    Her Excellency the Governor General in Council, on the recommendation of the Minister of the Environment, pursuant to section 27 of the Species at Risk Act, hereby makes the annexed Order Amending Schedules 1 to 3 to the Species at Risk Act.

COSEWIC Annual Reports

  • COSEWIC Annual Report - 2006 (2006-08-30)

    2006 Annual Report to the The Minister of the Environment and the Canadian Endangered Species Conservation Council (CESCC) from the Committee on the Status of Endangered Wildlife in Canada.
  • COSEWIC Annual Report - 2015-2016 (2016-10-13)

    Over the past year COSEWIC re-examined the status of 25 wildlife species; of these, the majority (68%) were re-assessed at the same or lower level of risk. Of a total of 45 species assessed, seven were assigned a status of Not at Risk (two re-assessments and five new assessments). To date, and with the submission of this report, COSEWIC’s assessments now include 724 wildlife species in various risk categories, including 320 Endangered, 172 Threatened, 209 Special Concern, and 23 Extirpated (i.e., no longer found in the wild in Canada). In addition, 15 wildlife species have been assessed as Extinct, 54 wildlife species have been designated as Data Deficient, and 177 have been assessed and assigned Not at Risk status.

Permits and Related Agreements

  • Explanation for issuing permit(#59-04-0389), persuant to the provisions of section 73 of SARA (2004-07-19)

    The activity involves live trapping survey of Pacific Water Shrew (Sorex bendirii)on First Nations land. A trap line will be installed adjacent to a drainage ditch. Historical records show the presence of S. bendirii in a neighboring catchment. Baited pitfalls will be installed as per the Best Management Practices Guideline recommendations, and checked every six (6) hours to minimize the risk of fatalities. Snow fencing will be raised 1-2" above the ground to ensure that no barriers to water shrew movements are created.
  • Explanation for issuing permit(#59-04-0401 ), persuant to the provisions of section 73 of SARA (2004-08-25)

    The activity involves the collection of soil samples from a former test facility on federal lands. A portion of the activity will take place within 100m of a riparian area that has been identified as suitable habitat for the Pacific Water Shrew, thus provincial Best Management Practices for this species indicate a potential impact. Specific sampling locations will be 'cleared' by a Registered Professional Biologist prior to soil sampling activities to reduce the potential for disturbing SARs.
  • Explanation for issuing permit(#59-04-0435), persuant to the provisions of section 73 of SARA (2004-10-02)

    A mapping and live pitfall trapping program for Pacific water shrew (PWS) will be conducted for two Department of National Defense properties. After the initial surveys to verify presence and quality of potential pacific water shrew habitat, the proponents will begin a live pitfall trapping program in habitats identified as low quality. Live pitfall traps will be set as in accordance with the 2004 Best Management Practices Guideline for PWS in Urban and Rural areas. These traps will be checked every 8 hours (3x/24 hrs). The shrew will only be kept long enough to photograph in the pitfall trap and then released. Once a capture is made along a waterway ranked as low quality, all traps will be pulled on that waterway.
  • Explanation for issuing permit(#SARA-PYR-2008-0083), persuant to the provisions of section 73 of SARA (2008-05-12)

    The immediate goal of this project is to acquire a natural resource inventory within the DND ASU Chilliwack. The proponent has demonstrated that compared to lethal and more invasive capture and marking techniques, their methods are either non-invasive or identified as the least-invasive alternative.
  • Explanation for issuing permit(#SARA-PYR-2009-0115), persuant to the provisions of section 73 of SARA (2009-08-17)

    The proponents will conduct ground surveys of species at risk including, amphibian visual encounter surveys, Oregon forestsnail ground searches, Badger burrow searches, Pacific water shrew habitat ratings, Spotted bat roost searches, snake foraging surveys, Monarch surveys (visual searches for larvae and adults), Great basin spadefoot egg mass surveys and Snake den surveys. No traps will be set and animals will only be handled where it is necessary for species identification and photo documentation. All animals will then be immediately released in the habitat where captured. No animals will be marked.

Consultation Documents

  • Consultation on Amending the List of Species under the Species at Risk Act Terrestrial Species: December 2006 (2006-12-28)

    The Government of Canada proclaimed the Species at Risk Act (SARA) on June 5, 2003 as part of its strategy for the protection of wildlife species at risk. Attached to the Act is Schedule 1, the list of the species that receive protection under SARA, hereinafter referred to as the 'SARA list'. Canadians are invited to comment on whether all or some of the species included in this document should be added to the SARA list. Please submit your comments by March 16, 2007 for species undergoing normal consultations and by March 14, 2008 for species undergoing extended consultations.
  • Consultation on Amending the List of Species under the Species at Risk Act: Terrestrial Species - January 2017 (2017-01-16)

    The Government of Canada is committed to preventing the disappearance of wildlife species at risk from our lands. As part of its strategy for realizing that commitment, on June 5, 2003, the Government of Canada proclaimed the Species at Risk Act (SARA). Attached to the Act is Schedule 1, the list of the species provided for under SARA, also called the List of Wildlife Species at Risk. Extirpated, Endangered and Threatened species on Schedule 1 benefit from the protection afforded by the prohibitions and from recovery planning requirements under SARA. Special Concern species benefit from its management planning requirements. Schedule 1 has grown from the original 233 to 521 wildlife species at risk. In 2016, on the recommendation of the Minister of the Environment, the Governor in Council approved listing proposals for 44 wildlife species. It is proposed that 23 species be added to Schedule 1, 18 be reclassified or have a change made to how they are defined (two wildlife species are being split into four), one species  be removed from Schedule 1, and another two species not be added. Listing proposals were published in Canada Gazette, part I for a 30-day public comment period and final listing decisions for all 44 species are expected in the first half of 2017.Please submit your comments byMay 11, 2017, for terrestrial species undergoing normal consultationsand byOctober 11, 2017, for terrestrial species undergoing extended consultations.For a description of the consultation paths these species will undergo, please see:Minister of Environment response to COSEWIC species at risk assessments: October 13, 2016 The COSEWIC Summaries of Terrestrial Species Eligible for Addition or Reclassification on Schedule 1 - January 2017

Critical Habitat Descriptions in the Canada Gazette

Recovery Document Posting Plans

  • Environment and Climate Change Canada's Three-Year Recovery Document Posting Plan (2016-07-06)

    Environment and Climate Change Canada’s Three-Year Recovery Document Posting Plan identifies the species for which recovery documents will be posted each fiscal year starting in 2014-2015. Posting this three year plan on the Species at Risk Public Registry is intended to provide transparency to partners, stakeholders, and the public about Environment and Climate Change Canada’s plan to develop and post these proposed recovery strategies and management plans. However, both the number of documents and the particular species that are posted in a given year may change slightly due to a variety of circumstances. Last update December 2, 2021
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