Pacific water shrew (Sorex bendirii) COSEWIC assessment and status report: chapter 10

This species is not listed by the IUCN. It was first designated Threatened by COSEWIC in 1994 (Galindo-Leal and Runciman 1994). It was re-examined and confirmed as Threatened in 2000 based on the 1994 report with an addendum of new occurrence records. The global heritage status rank is G4 (apparently secure), national ranks are N4 (apparently secure) for the United States and N1N2 (critically imperiled or imperiled) for Canada. State rankings are California S3S4 (vulnerable to apparently secure), Oregon S4, and Washington S4 (apparently secure). British Columbia has designated this species as S1S2 (critically imperiled or imperiled).

In British Columbia, the Pacific water shrew is protected from being killed or collected under the provincial Wildlife Act. This species is listed as an Identified Wildlife Species under the province’s Forest and Range Practices Act. Species listed under the Act are considered to be at risk and require special management by establishing Wildlife Habitat Areas (WHA). Guidelines under the Forest and Range Practices Act (Lindgren 2004) specify that a WHA for the Pacific water shrew must include a 30-m core area and a 45-m management zone on each side of a stream or wetland. Various recommendations are provided for silviculture. To date no WHAs have been designated for the Pacific water shrew. Some guidelines for protecting riparian habitats also exist under the Act. Despite the various guidelines, the provincial Forest and Range Practices Act provides minimal protection for this shrew. The Act only applies to provincial Crown land. Because less than 20% of the Canadian range is on Crown land, much of this species’ habitat is exempt from the Act. Moreover, the most serious threat to this species is loss of habitat from urban development on private lands--areas not covered by the Act.

Riparian habitat protection is also provided by the Riparian Areas Regulation of the provincial Fish Protection Act (British Columbia Ministry of Water, Air and Land Protection 2004). This new regulation comes into effect 31 March 2005 and it will transfer control of regulating riparian habitats to local municipalities. The regulations apply only to streams, creeks, ditches, or wetlands with fish or that are connected to freshwater ecosystems with fish in association with new residential, commercial and industrial development on land under local government jurisdiction. The Department of Fisheries and Oceans (DFO) also has guidelines for establishing Fisheries Sensitive Zones to protect fish and fish habitat (Fisheries and Oceans Canada 1993). The provincial Riparian Areas Regulation and the DFO regulations apply only to fish-bearing streams and creeks. Because the Pacific water shrew inhabits non-fish-bearing streams and small wetlands, these regulations are inadequate to protect this shrew (Craig and Vennesland 2004a).

None of the Pacific water shrew’s range is in a national park. Its known distributional area includes 5 provincial parks and 26 regional parks (Table 5). They encompass some 1,292 km². However, the amount of Pacific water shrew habitat contained in these protected areas is much smaller. For example, the two largest, Golden Ears and Pinecone Burke, are largely outside the known range of S. bendirii.  Moreover, they and other large parks in the Coast Mountains such as Cypress, Mount Seymour and Lynn Headwaters contain large areas above 800 m elevation, the upper elevational limits of this shrew. It is noteworthy that the largest and most extensive system of protected areas is on the north side of the Fraser River. In the heavily urbanized area on the south side of the Fraser River where the Pacific water shrew is most fragmented, protected areas consist of small and highly isolated regional parks with no connectivity.

Table 5. Provincial and regional district parks within the known range of Pacific water shrew (Sorex bendirii)
Park Location Area (ha) Sorex bendiriiRecords Comments
Provincial Park Cypress
3,012
  large area above elevational range
Provincial Park Cultus Lake
2,561
historical specimens  
Provincial Park Golden Ears
62,540
  mostly outside species range 
Provincial Park Indian Arm
6,826
   
Provincial Park Kilby
3
   
Provincial Park Mount Seymour
3,508
historical specimens large area above elevational range 
Provincial Park Pinecone Burke
38,000
  mostly outside species range
Provincial Park Rolley Lake
115
   
Greater Vancouver Regional District Park Aldergrove Lake
280
recent observations  
Greater Vancouver Regional District Park Belcarra
1,116
   
Greater Vancouver Regional District Park Boundary Bay
182
   
Greater Vancouver Regional District Park Brae Is. Reserve
71
   
Greater Vancouver Regional District Park Burnaby Lake
311
   
Greater Vancouver Regional District Park Campbell Valley
549
historical observations  
Greater Vancouver Regional District Park Capilano River
143
   
Greater Vancouver Regional District Park Colony Farm
262
   
Greater Vancouver Regional District Park Deas Island
72
   
Greater Vancouver Regional District Park Derby Reach
297
   
Greater Vancouver Regional District Park Fraser River Island
209
   
Greater Vancouver Regional District Park Glen Valley
112
   
Greater Vancouver Regional District Park Grant Narrows
6
   
Greater Vancouver Regional District Park Kanaka Creek
413
   
Greater Vancouver Regional District Park Lynn Headwaters
4,685
  large area above elevational range
Greater Vancouver Regional District Park Matsqui Trail
117
   
Greater Vancouver Regional District Park Minnekhada
211
   
Greater Vancouver Regional District Park Pacific Spirit
809
historical specimens  
Greater Vancouver Regional District Park Surrey Bend
362
   
Greater Vancouver Regional District Park Tynehead
261
   
Greater Vancouver Regional District Park Widgeon Marsh
559
   
Fraser Valley Regional District Park Neilson
10
   
Fraser Valley Regional District Park Cascade Falls
10
   
Fraser Valley Regional District Park Fraser River
17
   
Fraser Valley Regional District Park Sumas Mountain
1,497
recent captures  
Fraser Valley Regional District Park Cheam lake
93
recent captures  

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