Rock Vole(Microtus chrotorrhinus Miller)
From: Saunders, D. A. 1988. Adirondack Mammals. State University of New York, College of Environmental Science and Forestry. 216pp.
Description: The nose of this small rodent is yellowish orange, and thus another common name, the yellow-nosed vole. The rest of the body is yellowish to grayish brown above and silvery gray below. The ears protrude slightly from the surrounding fur. The short, sparsely haired tail is 42-64 mm (1.7-2.5 in) in length. Adults weigh 30-40 g (1.1-1.7 oz) and measure 140-185 mm (5.5-7.3 in) in total length.Range and Habitat: The range is from the northeastern Minnesota to northeastern Canada and southward in the U. S. to North Carolina and Tennessee. Within this geographic area, the rock vole occurs in small populations in scattered locations. This limited distribution is a consequence of habitat preference, and to come extent, results from the life style which makes this species difficult to capture. Thus, information about distribution is incomplete. Fewer then 300 specimens exist for the Adirondacks and these are mainly for Essex County (with one site nearby in Huntington Wildlife Forest, Hamilton County). Elevations range from 457 m (1,476 ft) at St. Hubert’s to 1,478 m (4,848 ft) on Whiteface Mountain. Rock voles are also likely to occur in other locations in the Adirondack Park.
As the name suggests, this species usually lives among the rocks suck as talus slopes, rocky outcrops, and boulder strewn floors of coniferous, deciduous, and mixed deciduous-coniferous forests in cool areas near flowing or subsurface water, mosses, ferns, and forbs. Rock voles build nests of plant fibers and Sphagnum in rock crevices, under rocks or logs.
Food and Feeding Behavior: Much of the life history of this species, sometimes described as one of the rarest North American voles, is sketchy or known only from a few studies in limited parts of the range. Fortunately, some of these studies have been conducted in the Adirondacks or nearby states. They indicate green vegetation constitutes most of the diet, with a few invertebrate and small quantities of fungi ingested as well. Mosses, ferns, fruit such as blackberries, and other plants, e.g. mountain avens, mountain alder, goldenrod, and bunchberry form the bulk of the diet. Captive rock voles, when offered the berries from several plants eat not only the berries and flowers of the bunchberry first, but also the entire plant before sampling other fruit. The rock vole cuts plant leaves and other plant parts and carries then to cracks between rocks, or under rocks and logs before consuming them.
Activity and Movement: Rock voles are active throughout the season, day and night, possibly foraging more in the morning than other times of the day. A substantial part of their activity is subsurface runs or burrows.
Reproduction: The breeding season is from late March until mid-October with 2-3 litters of 1-7 (average 3-4) young produced during this time. The gestation period is 19-21 days.
Predators: The bobcat and timber rattlesnake are predators known to prey upon rock voles.
- Social system - Scanty information is available about the mating system and social organization of rock voles. Although colonies are often referred to in the scientific literature, these may be disjunct populations occurring in the suitable habitat rather than social groups.
- Communication - This facet of the species’ biology is unknown. Individuals deposit their droppings in “toilets” which may serve as scent posts relaying specific information. Visual, vocal, tactile, and chemical signals are likely. Adult males and females have hip glands.
Crowell, K.L. 1980. High Peaks mystery mouse. Adirondack Life, 11(3):34-36.
French, T.W. and K.L. Crowell. 1985. Distribution and status of the yellow-nosed vole and rock shrew in New York. New York Fish and Game Journal, 32: 26-40.
Kilpatrick, C.W. and K.L. Crowell. 1985. Genetic variation of the rock vole, Microtus chrotorrhinus. Journal of Mammalogy, 66:94-101.
Kirkland, G.L., Jr. and R.J. Griffin. 1974. Microdistribution of small mammals at the coniferous -deciduous forest ecotone in northern New York. Journal of Mammalogy, 55:417-427.
Martin, R.L. 1971. The natural history and taxonomy of the rock vole, Microtus chrotorrhinus. Ph.D. Thesis. Univ. Conn., Storrs, CT.
Timm, R.M., L.R. Heaney and D.D. Baird. 1977. Natural history of rock voles (Microtus chrotorrhinus) in Minnesota. Canadian Field Naturalist, 91:177-181.
Whitaker, J.O., Jr. and R.L. Martin. 1977. Food habits of Microtus chrotorrhinus from New Hampshire, New York, Labrador, and Quebec. Journal of Mammalogy, 58:99-100.