Creeping vole

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Creeping vole
Microtus oregoni photographed at Wind River Experimental Forest

Least Concern  (IUCN 3.1)[1]

Secure  (NatureServe)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Cricetidae
Subfamily: Arvicolinae
Genus: Microtus
Subgenus: Pitymys
Species:
M. oregoni
Binomial name
Microtus oregoni
(Bachman, 1839)
See text.
Distribution of the creeping vole
Synonyms[3]
List
  • Arvicola oregoni
    Bachman, 1839
  • M. adocetus
    Merriam, 1908
  • M. bairdii
    Merriam, 1897
  • M. cantwelli
    Taylor, 1920
  • M. morosus
    Elliot, 1899
  • M. oregoni
    Miller, 1896
  • M. serpens
    Merriam, 1897

The creeping vole (Microtus oregoni), sometimes known as the Oregon meadow mouse, is a small rodent in the family Cricetidae. Ranging across the Pacific Northwest of North America, it is found in forests, grasslands, woodlands, and chaparral environments. The small-tailed, furry, brownish-gray mammal was first described in the scientific literature in 1839, from a specimen collected near the mouth of the Columbia River. The smallest vole in its range, it weighs around 19 g (11⁄16 oz). At birth, they weigh 1.6 g (1⁄16 oz), are naked, pink, unable to open their eyes, and the ear flaps completely cover the ear openings. Although not always common throughout their range, there are no major concerns for their survival as a species.

Taxonomy

The animal was described in 1839 by

type specimen was an older male collected November 2, 1836 near the mouth of the Columbia River in Oregon.[4] The specimen had been submitted to Bachman for review by John Kirk Townsend.[4] Subsequent authorities state that it was collected at Astoria, Oregon, which is at the mouth of the Columbia River.[5] In 1857, Baird placed Arvicola oregoni in a section Chilotus of the subgenus Arvicola of the genus Arvicola.[6] In 1874, PNAS paper, Coues reclassified Chilotus as a subgenus and refers to the animal as Arvicola (Chilotus) oregonus.[7][8] Miller subsequently reclassified the animal in the genus Microtus and maintained the subgenus Chilotus.[9] This was the first reference to the animal under its current scientific name Microtus oregoni.[5] It was subsequently reclassified to the subgenus Mynomes,[3] though the American Society of Mammalogists lumps that subgenus's species in with subgenus Pitymys.[10]

Description

Microtus oregoni skull

On average, creeping voles weigh around 19 g (11⁄16 oz) with a reported range of 14.5 to 27.5 g (1⁄2 to 1 oz)

molar teeth that help in differentiation.[5] Unlike other voles in the range, only the creeping vole and the (much larger) water vole have five plantar tubercles on the hindfeet.[5]

They are

plantigrade locomotion).[5] The foot pads have a moderate amount of fur.[5]

The fur markings are plumbeous to a dark brown or black.[5] There are sometimes yellowish hair markings as well.[5] The underside fur markings tend to be lighter beige to whitish.[5] The tail may be gray to black and often lighter below.[5]

Creeping voles have a relatively short tail, measuring less than 30% their total body length.

mammae, with two pairs present in each of the pectoral and inguinal regions.[5]

The skull of the creeping vole has a low, flat profile, with a long and slender snout.

zygomatic arches are somewhat delicate.[5] The incisive foramen is short and wide, but not so much as to be a distinguishing feature.[5] They have small molars.[5]

Distribution and habitat

Creeping voles are found in

South Yolla Bolly Mountain.[5]

They are found in coniferous forests and woodlands, grasslands, and chaparral.[2] They are found at sea level through altitudes of nearly 2,400 m (7,900 ft).

moist forests along the coast, but may do well in drier areas.[2]

It is suspected that ancestral voles migrated from Eurasia 1.2 million years ago.[5] However, no Pleistocene-era fossils of creeping voles have been identified.[5]

Behavior and ecology

Creeping voles establish nests of dry grass in protected areas, such as under logs.[1] The breeding season varies by latitude, but is mainly March to September in Oregon and British Columbia.[1] Gestation lasts around 23 days. Each litter bears three to four young and the females may produce four or five litters a year.[1] The naked, pink newborn young weigh around 1.6 g (1⁄16 oz).[11] Their eyes are closed and skin flaps cover the ear openings.[11]

Creeping vole skull and dentition

Creeping voles are primarily nocturnal, though they are sometimes active during the day.[1] They are herbivorous, probably eating forbs and grasses, as well as fungi.[1]

Genetics

Creeping vole females have XO sex chromosomes, while males have XY. Evolutionary geneticists have investigated these sex chromosomal features of creeping voles. A models for the evolution of creeping vole sex chromosomes was published by researchers from the University of Edinburgh in 2001.[12] Recently, it was discovered the Y chromosome has been lost, the male-determining chromosome is a second X that is largely homologous to the female X, and both the maternally inherited and male-specific sex chromosomes carry vestiges of the ancestral Y. This is quite unusual in mammals, as the XY system is fairly stable across a number of mammal species.[13]

Conservation status

Although it is not widely distributed and not always common, the creeping vole is listed as "Least Concern" by the IUCN Red List.[1] The justifications for the listing are the lack of major threats, the stability of populations, and the adaptability of the animal to environmental changes.[1] Treatment of Douglas-fir plantations with herbicides in British Columbia did not affect creeping vole populations.[1] No conservation concerns are raised, since there are thought to be sufficient areas of protected habitat within its range.[1] NatureServe lists the species as secure within its range.[2]

References

Footnotes:

  1. ^ a b c d e f g h i j k IUCN Red List 2016.
  2. ^ a b c d e f g NatureServe 2016.
  3. ^ a b Musser & Carleton 2005.
  4. ^ a b c d Bachman 1839, p. 61.
  5. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af Verts & Carraway 1985, p. 1.
  6. ^ Miller 1896, pp. 21–22.
  7. ^ Miller 1896, p. 22.
  8. ^ "Proceedings of the Academy of Natural Sciences of Philadelphia 1874, Volume 26, Page 198 | Document Viewer". Archived from the original on 2016-03-23. Retrieved 2014-12-11.
  9. ^ Miller 1896, pp. 60–62.
  10. ^ "Mammal Diversity Database (Version 1.11) [Data set]". Mammal Diversity Database. 2023.
  11. ^ a b Verts & Carraway 1985, p. 2.
  12. ^ Charlesworth & Dempsey 2001.
  13. S2CID 233872862
    .

Sources:

External links

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