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Microtus chrotorrhinus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA RODENTIA CRICETIDAE

Scientific Name: Microtus chrotorrhinus
Species Authority: (Miller, 1894)
Common Name(s):
English Rock Vole, Southern Rock Vole

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Linzey, A.V. & NatureServe (Hammerson, G., Whittaker, J.C. & Norris, S.J.)
Reviewer(s): Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global Mammal Assessment Team)
Justification:
Listed as Least Concern, because it has a very large range, it is common in many parts of its range, it appears to be somewhat adaptable to habitat disturbance and it is found in many protected areas.

Geographic Range [top]

Range Description: This species is known from Labrador, Canada, west to Ontario and northeastern Minnesota in the United States, southward at higher elevations through the Gaspe Peninsula, New Brunswick, New England, New York, and northeastern Pennsylvania, and disjunctly in the southern Appalachians to Virginia, western North Carolina, and eastern Tennessee (Handley 1991). A 400 km disjunction separates populations in northeastern Pennsylvania from those in northern West Virginia (Kirtland and Jannett 1982; Kirtland pers. comm., 1994).
Countries:
Native:
Canada (Labrador, New Brunswick, Newfoundland I, Nova Scotia, Ontario, Québec); United States (Maine, Maryland, Minnesota, New Hampshire, New York, North Carolina, Pennsylvania, South Carolina, Vermont, Virginia, West Virginia)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: It is considered common in the northern range, but much less abundant in the southern and eastern range. Too little is known to accurately assess current population trends. Historically, a long-term decline appears to have occurred, related to land use and/or climate change (Christian pers. comm., 1994). Rangewide surveys are needed to clarify the status and distribution, especially of subspecies carolinensis.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: It prefers cool, damp, coniferous and mixed forests at higher elevations in the Appalachians; mossy rocky areas throughout Canada. Optimal habitat is ferns/mossy debris near flowing water in coniferous forests. It also occupies deciduous forest/spruce clearcuts (mainly recent cuts), forest ecotones, grassy balds near forest, and sterile-looking rocky road fills. Occupies shallow burrows and runways.

Nests probably are placed under logs or in similar protected sites. They are made of moss with a lining of grass and have multiple entrance tunnels. Breeding season is from March to mid-October. Gestation lasts 19-21 days. Up to three litters of one to seven (typically three to four) young are reared each year. Birthing peaks in late spring-early summer. Spring progeny breed in their first summer. Males are sexually mature at 15 cm body length and 30 g. Females reach sexual maturity at about 13 cm body length and 30 g. See Kirkland (1977), and DeGraaf and Rudis (1986).

Small isolated colonies seem to be the rule (Banfield 1974). Home ranges probably are less than an acre. Martin (1971) thought that records from atypical habitat may represent expansion of populations under favourable conditions. These might also be dispersing individuals.

Frequent associates include the red-backed vole, deer mouse, and often with masked, smoky, and short-tailed shrews (Martin 1971; Kirkland 1977). Martin (1971) found no evidence of rivalry between red-backed and rock voles, but thought that the latter may competitively exclude the meadow vole from prime rock vole habitat where the two occur together. Deer may be an important competitor in some areas.

Rock vole remains have been found in the stomachs of a bobcat in the Great Smoky Mountains National Park (Linzey and Linzey 1968) and three rattlesnakes and a copperhead from the same area. Other predators doubtless include other snakes, weasels, foxes, and short-tailed shrews. Merritt (1987) stated that "predation by avian predators is probably minimized because of inaccessibility of its foraging zone."

Common parasites include fleas, mites, ticks, botflies, tapeworms and roundworms. Six specimens collected in New York in 1947 "exhibited severe damage to the ears by an unidentified fungus" (Martin 1972). Fecal pellets are deposited in special latrine areas. Martin (1971) found a latrine, 50 cm in diameter and 24 cm deep, in a rock crevice.

Diet includes foliage, stems, and fruits of herbaceous plants (forbs more often than grasses and sedges), and fungi. Active day or night (Handley 1991). Also reported as primarily diurnal, with greatest feeding activity taking place in the morning (Martin 1971). This vole does not hibernate; it is active all year.
Systems: Terrestrial

Threats [top]

Major Threat(s): The pristine forests that support this species are a declining resource, especially in the southern portion of the range.
The principal current threat probably is destruction of the species' habitat, but this may be less of a problem than for many other rare species; the preferred habitat, high elevation talus slopes (in the eastern portions of the range) and other rocky areas, is generally unsuitable for development. Abundant rocks also provide a very uniform subterranean environment that is not particularly vulnerable to disturbance. However, Fichtel (pers. comm., 1992), in discussing threats to the habitat of the long-tailed shrew (Sorex dispar) in Vermont, suggested that ski area development may destroy habitats of this sort. Logging does not appear to have any immediate adverse impact (Kirkland 1977). In fact, at three West Virginia sites, rock voles were more than twice as abundant on recent clearcuts as on adjacent uncut stands (Kirkland 1977). The rock vole is a habitat specialist and occurs in isolated colonies throughout its range (Banfield 1974, Kirkland and Jannett 1982, Majumdar et al. 1986, Kirkland and Krim 1990). Chemical and heavy metal pollution may have less effect on this primarily vegetarian species than on predators in the same habitat. Brooks and Healy (1988), working in West Virginia and Massachusetts hardwood forests, concluded that both intermediate thinning and clearcutting have minimal or ephemeral effects on small mammal communities, but that "long-term, high deer populations may permanently alter habitat structure to the extent that changes occur in small mammal community composition." Overall, considering this is a wide ranging species which appears to be somewhat adaptable, it is considered that there are no major threats to this species at present.

Conservation Actions [top]

Conservation Actions: Most of the North Carolina population is within Great Smoky Mountains National Park. Many other populations are in national forests, parks, or other public lands affording some protection. Many populations are somewhat protected by being in remote areas not currently impacted by human activities. The primary need is to protect the habitat of the rock vole from gross disturbance.

Citation: Linzey, A.V. & NatureServe (Hammerson, G., Whittaker, J.C. & Norris, S.J.) 2008. Microtus chrotorrhinus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 27 November 2014.
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