132.

Rock Vole

Microtus chrotorrhinus

French: Campagnol des rochers / German: Gelbnasen-Wihlimaus / Spanish: Topillo de roca

Other common names: Southern Rock Vole, Yellow-nosed Vole

Taxonomy. Arvicola chrotorrhinus G. S. Miller, 1894, head of Tuckerman’s Ravine, 5300 ft. (= 1615 m), Mt. Washington, Coos County, New Hampshire, USA.

Three subspecies are recognized.

Subspecies and Distribution.

M.c.chrotorrhinusG.S.Miller,1894—S&EOntario,SQuebec,andWNewBrunswick,Canada,andNEMinnesota,NewYork,extremeWMassachusetts,Vermont,NewHampshire,Maine,NEPennsylvania, andextremeNWNewJersey,USA.

M.c.carolinensisKomarek,1932—ETennesseeandWNorthCarolina,USA.

M. c. ravus Bangs, 1898 — E Labrador and extreme E Quebec, Canada.

Descriptive notes. Head-body 92-121 mm, tail 42-64 mm, ear 12-18 mm, hindfoot 18-24 mm; weight 30-40 g. Sexual dimorphism is minimal, with males slightly larger than females. Dorsum of the Rock Vole is dull gray/brownish yellow to bright glossy brownish yellow. It has yellowish orange tinge to snout—a feature it shares only with the Taiga Vole ( M. xanthognathus) among species of North American Microtus . There is considerable regional variation in dentition of Rock Voles. Chromosomal complement is 2n = 60, FN = 64.

Habitat. Coniferous and mixed forests at higher elevations in southern parts of its distribution; rocky substrates and talus slopes in coniferous forests farther north in Canada (where mossy rocks and ferns near streams are suitable for shallow burrows and runways); and forest ecotonal habitats and after clearcut logging.

Food and Feeding. Diet is primarily grasses, sedges, and other herbaceous plants and fungi. Bunchberry ( Cornus canadensis, Cornaceae), bluebead lilly ( Clintonia borealis, Liliacaeae), blueberry ( Vaccinium angustifolium, Ericaceae), and raspberry ( Rubus strigosa, Rosaceae) are commonly eaten.

Breeding. Nests of Rock Voles are lined with grass and often under logs or stumps. Breeding occurs in March—October, and gestation lasts 19-21 days. Breeding season is longer in southern parts of the distribution where up to three litters of 1-7 young are produced annually. Larger average litters have been reported in northern populations. Young born in April-May can reproduce the same year.

Activity patterns. Rock Voles are active year-round. They are thought to be primarily diurnal, but nocturnal activity has been observed. They spend most time in subterranean activity.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Least Concern on The IUCN Red List.

Bibliography. Cassola (2016i), Hafner et al. (1998), Hall (1981), Kirkland (1977a, 1977b), Kirkland & Jannett (1982), Musser & Carleton (2005), Timm et al. (1977), Wilson & Ruff (1999).