Pacific water shrew (Sorex bendirii) COSEWIC assessment and status report: chapter 11
Sorex bendirii
Pacific water shrew – musaraigne de Bendire
Range of Occurrence in Canada:
British Columbia
Extent and Area Information
Extent of occurrence (EO) (km²)
3,350 km² (see Map (Figure 3) of historical and recent occurrences)
Specify trend in EO
Unknown
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km²) -
Unknown
Specify trend in AO -
Are there extreme fluctuations in AO?
-
Number of known or inferred current locations
44
Specify trend in #
Unknown
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat
Habitat declining
Population Information
Generation time (average age of parents in the population)
1 year
Number of mature individuals
Unknown
Total population trend:
Unknown
% decline over the last/next 10 years or 3 generations.
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
Yes
Specify trend in number of populations
-
Are there extreme fluctuations in number of populations?
-
List populations with number of mature individuals in each:
Threats (actual or imminent threats to populations or habitats)
- Habits loss and habitat fragmentation from urban development (roads, housing, commercial, industrial)
- Habitat loss from forest harvesting
- Water quality degradation from development
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: Washington S4, status in county bordering Canada unknown
Is immigration known or possible?
Yes
Would immigrants be adapted to survive in Canada?
Yes
Is there sufficient habitat for immigrants in Canada?
No?
Is rescue from outside populations likely?
No?
Quantitative Analysis
Current Status
COSEWIC: Threatened in April 1994 and May 2000; Endangered in April 2006
Status and Reasons for Designation
Status: Endangered
Alpha-numeric code: B1ab(i,iii)
Reasons for Designation: 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.
Applicability of Criteria
Criterion A: While there is no direct evidence of a declining population trend, the available habitat is rapidly declining. However, there are no data on population size. It appears to be rare throughout its range.
Criterion B: EO less than 5,000 km²; AO is unknown; Continued decline in suitable habitat and remaining habitat patches are highly fragmented.
Criterion C: Total population size is unknown but likely in the thousands. No direct evidence for decline, but suitable habitat has declined dramatically.
Criterion D: Total population size is unknown but likely in the thousands.
Criterion E: Not available.
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