The southern red-backed vole is a small, moderately short-tailed mouse with a reddish back, grayish sides, and a silvery belly. A bright reddish band runs from the forehead to the rump. This species is common to abundant in the Park's spruce-fir forests, although Linzey has also collected it in deciduous woodlands. This was the most abundant small mammal (37% of all small mammals captured) in a study in the spruce-fir zone (Smith and Mouzon, 1985). It has been recorded in the park at elevations ranging from 1,750 feet to 6,620 feet.

Species Measurements:
- Adult Total Length: 120-165 mm (4?-6? in.)
- Tail: 35-50 mm (1⅜-2 in.)
- Hind Foot: 17-22 mm (⅝-⅞ in.)
- Weight: 14-42 g (?-1? oz.)

Physical Characteristics:
The southern red-backed vole is a small, moderately short-tailed mouse with a reddish back, grayish sides, and a silvery belly. A bright reddish band runs from the forehead to the rump. The fur is generally longer and more dense in winter than in summer. The bicolored tail is dark brown above and whitish below.

Habitat:
Cool, damp areas are preferred, including moss-covered logs and rocks, deep crevices among boulders on hillsides, along small boulder-strewn streams, and in rhododendron thickets. These semifossorial voles travel in natural runways along and beneath bogs, rocks and roots of trees. The Komareks frequently found Clethrionomys among mossy rocks in humid forests, but they also took specimens at they also took specimens at the bases of isolated shrubs on top of Spence Field, a grassy bald. This was the most abundant small mammal (37% of all small mammals captured) in a study in the spruce-fir zone (Smith and Mouzon, 1985).

Reproduction:
The breeding season in the park probably extends from early spring until fall. Nursing females or females with embryos have been recorded on the following dates: April 25 (nursing); April 30, 4 (CR=5 mm); July 4, 4 (25 mm); July 4, pregnant; July 4, nursing; July 17, 2 (2R, 0L, very small); July 17, 2 (1R, 1L); July 17, 3 (2R, 1L); July 17, placental scars (1R, 3L; nursing); July 21, 4 (3 with CR about 13 mm; 1 very small); July 31, 3 (CR=16.5 mm); and August 29 (nursing). No embryos or placental scars were recorded for seven females in July or in December. Eleven males in breeding condition were noted during July. Half-grown individuals have been taken 31 July and 23 August (Komarek and Komarek, 1938; Linzey and Linzey, 1968). Smith and Mouzon (1985) recorded many males in breeding condition and pregnant and lactating females from mid-August to mid-October in the spruce-fir zone.
From two to eight young are born following a gestation period of 17 - 19 days. Newborn red-backed voles are pink, hairless, and have their eyes and ears closed. The eyes open between 10 and 15 days and weaning is usually completed by day 17. Individuals reach sexual maturity by three months of age.

Feeding Habits:
Red-backed voles use grass, stems, moss, and dead leaves to line a globular nest that is 75 - 100 mm in diameter. Nests are usually located in natural cavities or in abandoned holes.
Examination of the stomachs of 27 Clethrionomys taken during July (19) and December (8) revealed vegetation forming the bulk of the diet (64.8% of the total volume) (Linzey and Linzey, 1973). Seeds amounted to nearly 12%, while animal food comprised only 4.4% of the total volume.

Longevity:
Maximum longevity is approximately 20 months (Linzey, 1995a).

Terrestrial Ecology:
Red-backed voles may be active at any time of the day or night and during all seasons of the year.

Diseases:
The enterococci Streptococcus faecalis and Streptococcus faecium were recorded in fecal specimens by Mundt (1963).

Predators and Defense:
In the park, this species has been found in the stomach of a timber rattlesnake (Crotalus horridus) (Savage, 1967).

Parasites:
Komarek and Komarek (1938) found warbles (Cuterebra sp.) to be common in this species. They were found most frequently in males and almost always near the testes. Cuterebra was also recorded by Pfitzer (1950). Linzey has recorded fleas (Ctenophthalmus pseudagyrtes, Peromyscopsylla catatina, and Catallagia borealis) and a tick (Ixodes angustus) (Linzey, 1995b). Also see Ctenophthalmus pseudagyrtes.

The red-backed vole occurs throughout most of Canada and the northern tier of the United States. The range extends south in the Appalachian Mountains to western North Carolina and in the Rocky Mountains to Arizona and New Mexico.

This species is common to abundant in the spruce-fir forests, although Linzey has also collected it in deciduous woodlands. Clethrionomys has been recorded in the park at elevations ranging from 1,750 feet to 6,620 feet.

References:

Komarek, E. V. and R. Komarek. 1938. Mammals of the Great Smoky Mountains. Bulletin of the Chicago Academy of Sciences 5(6): 137-162.

Linzey, A.V. and D.W. Linzey. 1973. Notes on Food of Small Mammals from Great Smoky Mountains National Park, Tennessee-North Carolina. Journal of the Elisha Mitchell Scientific Society 89 (1 and 2): 6-14.

Merritt, J.F. 1981. Clethrionomys gapperi. Mammalian Species No. 146: 1-9. American Society of Mammalogists.

Merritt, J.F. 1999. Southern Red-backed Vole. Pages 613-615. In: D.E. Wilson, and S. Ruff (eds.). The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, D.C.

Mundt, J.O. 1963. Occurrence of Enterococci in Animals in a Wild Environment. Applied Microbiology. 11: 136-140.

Savage, T. 1967. The Diet of Rattlesnakes and Copperheads in the Great Smoky Mountains National Park. Copeia 1967 (1): 226-227.

Smith, T.R., and J.M. Mouzon. 1985. Small Mammal Survey in the Spruce-Fir Zone of Great Smoky Mountains National Park. Typewritten final research report. In library of Great Smoky Mountains National Park.

Linzey, D. W. 1995a. Mammals of Great Smoky Mountains National Park. The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.

Linzey, D. W. 1995b. Mammals of Great Smoky Mountains National Park-1995 Update. Journal of the Elisha Mitchell Scientific Society 111(1): 1-81.

Linzey, D. W. 1998. The Mammals of Virginia. The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.