Potential SouthCoastOccurrenceRange

Distribution: Of the eight sub-species of M. gapperi in BC, two occur on the SouthCoast. One sub-species C. g. occidentalis, is known in the province from only 2 historical records in the Vancouver area (Point Grey and StanleyPark), and may be extirpated in British Columbia. There is still a debate as to whether this sub-species is (was) actually a separate species (Nagorsen 1990). The more widespread M.g. cascadensis , also a coastal sub-species ranges in the watersheds and valleys west of the Cascades and south of the CentralCoast.

Description:Length 70-112 mm, tail 25-60 mm, Weight 6-42 g. Hamster like, voles have small ears, short furred tails and resemble large, plump field mice more than insectivores like shrews or moles. Red-backed voles have dense, long, soft fur in winter changing to shorter, coarser fur in summer. Dorsal coloration is dark gray with a pronounced chestnut cap, nape and saddle running from head to tail. Face and sides appear golden brown and the ventral area is dark slate gray to almost white. Males and females are similar in size and color; juveniles tend to be darker than adults.

Diet: Feeds chiefly on vegetation, seeds, nuts, fungi, some insects; summer diet for most western populations consists almost entirely of fungi. This dietary preference is actually a critical function for dispersing viable spores of mycorrhizal fungi and nitrogen-fixing bacteria (see Maser and Maser 1988) that contribute to forest health.

Looks like? This species is most likely to be confused with the more common Townsend’s vole where these species overlap (forest edges, wetlands and old-field to wooded transition areas). The most characteristic difference is the distinct chestnut dorsal fur and lighter belly fur, not found on the more evenly coloured grey-brown Townsend’s vole.

Primary Habitat:Red-backed voles inhabit cool, mossy and rocky forested areas. While coniferous forests are preferred, deciduous or mixed forests are also utilized.

Secondary Habitat: While red-backed voles are regarded as an ecological indicator of old-growth conditions in the Rocky Mountains, they also use second-growth areas, which tend to be more typical in the southwest part of their range (e.g. LowerFraserValley).

Critical Feature: Mossy logs and tree roots in coniferous forests are optimal. Nests are generally constructed under the roots of stumps, logs, or brush piles, but may be located in holes or branches of trees high above the ground. During the winter, nests are sometimes placed directly on the ground under the snow, with tunnels radiating from the nest under the snow. Unlike Townsend’s vole, M. gapperi does not dig tunnels or create covered runways, instead it uses the burrows of moles and other small mammals.

Seasonal Life Cycle

Jan / Feb / Mar / Apr / May / Jun / Jul / Aug / Sep / Oct / Nov / Dec

Habitat Guild Still waters (wetlands), riparian and interior forests, bedrock outcroppings and talus.

Threats

Wide highways with heavy traffic and highways with continuous solid barriers that prevent rodent passage (Oxley et al. 1974, Wilkins 1982, Garland and Bradley 1984).

Major water bodies, arbitrarily set at those greater than 50 meters across in ice-free areas can be a barrier to dispersal.

Rarity contributes to knowledge gaps in occurrence, population, and abundance.

Distribution coincides with a heavily urbanized area undergoing rapid development

and habitat change.

Domestic pet (feral and free ranging cat) predation.

Predation by accipiters and owls as well as small carnivores (weasels and coyotes).

Damage or disruption to nests, litter abandonment and possibly extirpation of local populations may occur where logging, removal of standing, dead and downed wood and other land use activities occur.

Conservation Objectives

Restore the quality of urban and rural forests that have been impacted by logging, clearing and infilling.

The issue of M. gapperi sub-species taxonomic differences needs to be addressed through modern DNA analysis. Conservation and management need gaps will continue until the status and distribution of this subspecies known.

Inventories specifically aimed at this species are needed to determine whether M.g. occidentalis still remains in British Columbia.

Check List of Management Practices

Assess, inventory and monitor using methodology setout in the RISC standards # 31 Inventory Methods for Small Mammals: Shrews, Voles, Mice & Rats (Version 2.0)

For site series ranked as high or moderate capability for red-backed vole - assume the species to be present in that area and implement protective measures.

Home range varies from 0.25 to 3.5 acres (Merritt and Merritt 1978). Experimentation by Gillis and Nams (1998) suggests that populations separated by an inter-patch distance of 60-70 m likely would be isolated from one another.

Permanently maintain core patches of forested stands with understory vegetation and downed wood features to protect home ranges (a minimum of .5ha).

This “core zone” should have limited access and no disturbance and should be linked to other adjacent patches to prevent source sinks.

Linear habitat such as riparian buffers should be maintained similar to those of Pacific water shrew (i.e. 100 meters) to protect the broadest range of habitat features and functions (ELI 2003).

Sightings, specimens, or observations of activities threatening its habitat should be reported to the regional Species at Risk Biologist at the Ministry of Environment office.

Mitigation Measures

Restore the quality of upland and riparian forest habitats and maintain connectivity corridors that have been impacted by development, logging and other activities.

Conserve structural diversity and retain understory plant communities that are used for cover and foraging.

Voles will swim short distances, road culvert size should be a minimum of 2 meters in diameter with a natural substrate bottom to allow for passage and short enough to prevent entrapment

Wildlife underpasses are preferred and should be installed at appropriate intervals where high vehicular use corridors exist or are planned.

Slash piles, snags, and downed logs should be left for foraging areas after clearing to maintain and restore habitat connectivity.

Implement agricultural land set-asides and stewardship agreements, work towards covenant and acquisition opportunities to maintain forest patches and connectivity corridors.

Where developments are planned, ensure adequate long-term control of domestic pets.

Main References & literature Cited:

Conserving Mammals at Risk: The Role of Taxonomy. David W. Nagorsen 1999. B.C. Ministry of Environment.

Rare amphibians, reptiles, and mammals of British Columbia. Cannings, S.G., L.R. Ramsay, D.F. Fraser, and M.A. Fraker. 1999.

Develop With Care: Environmental Guidelines for Urban and Rural Land Development in British Columbia.

CONSERVATIONTHRESHOLDSFORLAND USE PLANNERS. The Environmental Law Institute®. 2003.

BC Species & Ecosystems Explorer (BC Conservation Data Center Summary Report)

Animal Diversity Web

NatureServe Explorer -

Committee on the Status of Endangered Wildlife in Canada:

Image credits:

RBV- Phil Myers

Habitat - Pamela Zevit

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Field Guide to Select Species of Conservation Concern for the SouthCoast of British Columbia

Red-backed Vole - Draft 2008