Microtus chrotorrhinus
Rock Vole
(Microtus chrotorrhinus) | |
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Range | |
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Taxonomic classification | |
Order: | Rodentia |
Suborder: | Supramyomorpha |
Infraorder: | Myomorphi |
Superfamily: | Muroidea |
Family: | Cricetidae |
Subfamily: | Arvicolinae |
Tribe: | Microtini |
Genus: | Microtus |
Subgenus: | Pitymys |
Binomial details | |
Microtus chrotorrhinus (G. S. Miller, 1894) |
Description
From Best & Hunt (2020): "Rock voles are yellowish-brown to dark grayish-brown with a yellowish-orange rostrum. Some individuals have a yellowish rump. The ventrum is grayish, feet are silver-gray on the top, and the tail is rich brown on top and paler on the underside. This is a medium-sized vole."
From Kirkland & Jannett (1982): "Upper parts are grayish bister to bright glossy bister with black-tipped hairs. The face has a yellowish to dull orange-rufous wash. This is most prominent on the snout and decreases in intensity towards the ears. The extent and intensity of the ochraceous pigmentation varies with age and geographic locality. Some individuals have a dull yellowish wash on the rump. Specimens in the southern Appalachians are darker (Komarek, 1932), whereas those from Labrador are grayer (Bangs, 1896)."
Image on GBIF: https://www.gbif.org/occurrence/1847646333
External measurements
Length measurements are in millimeters (mm) and weight measurements are in grams (g), unless stated otherwise. If available, the sample size (n=) is provided. If a range is not provided and n= is not given, then the listed measurement represents an average.
Part of range | Reference | Total length | Tail length | Hindfoot length | Ear length | Mass |
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Carolinas, Virginia, Maryland | Webster et al. (1985) | 144–177 | 46–55 | 30–48 | ||
Minnesota | Hazard (1982) | 132–172 | 38–49 | 19–21 | 12–16 | 21.8–46.0 |
not reported | Kirkland & Jannett Jr. (1982) | 140–185 | 42–64 | 18–24 | 12–18 | 30–48 |
Virginia | Linzey (1998) | 140–175 | 35–51 | 25–57 |
Skull
Similar species
From Kirkland & Jannett (1982): "The rock vole resembles the meadow vole (Microtus pennsylvanicus) in size and proportions but is distinguished by its yellowish-orange snout and yellow-brown dorsal pelage. M. pennsylvanicus lacks this ochraceous facial wash and generally has a dark chestnut brown dorsum. The skulls of the two voles can be differentiated on the basis of the size and shape of the incisive foramina and the morphology of the second upper molar. The incisive foramina of adult rock voles are shorter (generally <4.74 mm) and are not markedly tapered posteriorly. In M. pennsylvanicus, the incisive foramina are longer (generally >5.00 mm) and are constricted posteriorly. The M2 of M. chrotorrhinus has three closed dentine triangles (in addition to an anterior loop) and no posterior loop. The M2 of M. pennsylvanicus has three closed triangles of dentine followed by a posterior loop of variable size and shape. The rock and meadow voles are usually ecologically segregated with the former being a forest-dweller and the latter a resident of meadows and other herbaceous communities. On occasion, meadow voles (presumably dispersing individuals) are taken in forests.
"The yellow-cheeked vole (Microtus xanthognathus) is the only other North American Microtus possessing a yellowish-orange snout and yellowish-brown dorsal pelage. Beyond this superficial resemblance, these two voles are easily distinguishable. M. xanthognathus is considerably larger, having total, tail and hindfoot lengths of 186 to 226 mm, 45 to 53 mm , and 24 to 27 mm, respectively (Banfield , 1974). The flank glands are conspicuous in M. xanthognathus but are lacking in M. chrotorrhinus,'which possesses hip glands instead (Jannett, unpubl.). The incisive foramina of M . xanthognathus are long and taper posteriorly. In the field , M. chrotorrhinus might be confused with the heather vole (Phenacomys intermedius), which is sympatric with the rock vole over part of its range (peterson, 1966). Some populations of Phenacomys have yellow faces, but their tails are shorter (24 to 41 mm) than those of rock voles (Whitaker, 1980). The molars of Phenacomys are rooted in adults; they are rootless and evergrowing in M. chrotorrhinus. In Phenacomys, the inner reentrant angles of the lower molars are deeper than the outer. The reentrant angles of the inner and outer sides of the lower molars are approximately equal in M. chrotorrhinus."
References
Bangs O. 1896. On a small collection of mammals from Lake Edward, Quebec. Proc. BioI. Soc. Washington, 10:45-52.
Best TL, Hunt JL. 2020. Mammals of the southeastern United States. Tuscaloosa (AL, USA): University Alabama Press.
Hazard EB. 1982. The mammals of Minnesota. Minneapolis (MN, USA): University of Minnesota Press.
Kirkland GL, Jannett FJ. 1982. Microtus chrotorrhinus. Mammalian species (180):1-5.
Komarek EV. 1932. Distribution of Microtus chrotorrhinus, with description of a new subspecies. Journal of Mammalogy 13:155-158.
Linzey DW. 1998. The mammals of Virginia. McDonald & Woodward Publishing.
Webster WD, Parnell JF, Biggs WC. 1985. Mammals of the Carolinas, Virginia, and Maryland. Chapel Hill (NC, USA): University of North Carolina Press.