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Water Vole
Microtus richardsoni
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S3
External links
General information
The water vole, Microtus richardsoni, occurs in the northwestern United States and parts of southwestern Canada. The species is found in mountainous areas of northern and central Utah, where it prefers alpine and sub-alpine meadows. As their name implies, water voles are generally found near water. They are excellent swimmers, and their burrows often have openings below the water's surface.
Females may have two litters of two to nine young each year. Water voles eat a variety of vegetation, including leaves, grasses, seeds, and roots; invertebrates are also consumed.
Phenology
Active throughout the year.
Species range
Northwestern North America. Two disjunct ranges: southwestern British Columbia south through Washington and Oregon; southeastern British Columbia and southwestern Alberta through eastern Oregon, eastern Washington, western Montana, western Wyoming, Idaho, to central Utah (Hall 1981).
Habitat
Subalpine and alpine meadows close to water, especially swift, clear, spring-fed or glacial streams with gravel bottoms. Marshes, pond edges. Uses underground nests throughout the year. Burrows into streambanks. Makes runways in wet meadows.
Food habits
Leaves and occasionally stems of forbs are the major foods. Also eats grasses, sedges and willows. May eat some seeds and insects. Feeds on subterranean parts of plants throughout the year.
Ecology
Populations may fluctuate dramatically yearly or seasonally. In Alberta, monthly density estimates (June-September) in several streamside sites ranged from 0.2-12.2 per ha; seasonal recruitment increased population size 0.8-6.2 times, highest numbers in August or September (Ludwig 1988).
Reproductive characteristics
In Alberta, mating activity was recorded late May or early June through August or September; young first entered trappable population in early July; maximum of 2 litters per year; average litter size about 5-6 (range 2-9); about 26% of young bred before their first winter (Ludwig 1988). In laboratory animals gestation lasted a minimum of 22 days.
References
- Biotics Database. 2005. Utah Division of Wildlife Resources, NatureServe, and the network of Natural Heritage Programs and Conservation Data Centers.
- Burt, W. H. and R. P. Grossenheider. 1980. A field guide to the mammals. Houghton Mifflin Company, Boston. 289 pp.
