Microtus oregoni
Creeping Vole
(Microtus oregoni) | |
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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 oregoni (Bachman, 1839) |
Description
From Carraway & Verts (1985): "The fur is short and dense. The dorsum is sooty gray to dark brown or black, often with a mixture of yellowish hairs; the venter is dusky washed with buff or white; the tail is sooty or blackish, and slightly lighter below; and fur on the ears is black (Bailey, 1900; Hall, 1981; Ingles, 1965)."
From Naughton (2012): "Creeping voles are the smallest vole in their range. They have tiny dark eyes(< 4 mm in diameter) and a short, slightly bicoloured tail that is less than 30% of the vole's total length. Their back and sides are dark reddish brown and their belly fur is dark grey with a brownish wash. Body fur is short, thick and fine with the guard hairs barely protruding beyond the underfur, giving the plush coat a very shrew-like appearance. Fur on the upper parts of the feet is light brown. Ears are short and rounded and almost concealed by the fur. These voles have eight mammae. Each adult undergoes two annual molts, one in spring and early summer and one in autumn."
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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California | Jameson & Peeters (2004) | 129–154 | 32–42 | 16–19 | 9–10 | 18–22 |
Oregon (Coast Range and northern Cascade Range) | Verts & Carraway (1998) | females: 108–142 (n=30); males: 112–146 (n=30) | females: 28–42 (n=30); males: 26–43 (n=30) | females: 15–19 (n=30); males: 15–27 (n=30) | females: 12.6–23.5 (n=30); males: 13.4–32.8 (n=30) | |
Oregon (Klamath County, south of Crater Lake) | Verts & Carraway (1998) | male: 130 (n=1) | male: 32 (n=1) | male: 17 (n=1) |
Skull
From Carraway & Verts (1985): "Molars are small; m3 has two or three closed triangles; M1 has five closed triangles; in M2 the anterior pair of triangles are usually confluent; and M3 has three transverse loops (Bailey, 1900; Hall, 1981)."
Similar species
From Carraway & Verts (1985): "Microtus oregoni can be distinguished from sympatric and parapatric voles on the Pacific coast on the basis of tiny eyes (opening about 2 mm in diameter), unrooted molars, reentrant angles on lingual side of lower molars about equal in depth to those on labial side, and M3 with three loops of enamel on the lingual side. Adult creeping voles are the only Microtus in the Pacific Northwest, except M. richardsoni, with five plantar tubercles on the hindfeet (Hall, 1981)."
References
Bachman J. 1839. Description of several new species of American quadrupeds. Journal of the Academy of Natural Sciences of Philadelphia 8(1):57-74.
Bailey V. 1900. A revision of American voles of the genus Microtus. North American Fauna, 17:1.
Carraway LN, Verts BJ. 1985. Microtus oregoni. Mammalian Species (233):1-6.
Hall, ER. 1981. The mammals of North America. Second edition. John Wiley and Sons, New York, 2:60.
Ingles LG. 1965. Mammals of the Pacific states: California, Oregon, and Washington. Stanford (CA, USA): Stanford University Press.
Jameson EW, Peeters HJ. 2004. Mammals of California (No. 66). Berkeley (CA, USA): University of California Press.
Naughton D. 2012. The natural history of Canadian mammals. Toronto (ON, CA): University of Toronto Press.