Identification and Status of the Olympic Shrew (Sorex rohweri) in British Columbia

Abstract

In 2007, a new species of shrew, Sorex rohweri, was described from western Washington. We examined historical museum and recent voucher specimens to assess identification criteria and status of this new species in British Columbia. Most similar morphologically to Sorex cinereus and Sorex vagrans, S. rohweri can be identified by a combination of dental and skull traits. Three-group discriminant analyses of 100 specimens based on as few as 6 skull measurements correctly assigned 98% of individuals to the 3 species. The available records, consisting of 18 specimens from 13 locations, suggest that S. rohweri has a small range extent of about 360 km2 in the lower Fraser River basin confined to the south side of the Fraser River. The combination of the shrew's association with forested habitats in a region greatly affected by agricultural and urban development, the concentration of recent records from Burns Bog, a fragmented 3000-ha patch of natural habitat, and the isolation of the British Columbian population from populations in Washington make it a species of national conservation concern in Canada.