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The montane vole (''Microtus montanus'') is a species of
vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...
native to the western
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
and
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
.


Description

Montane voles are medium-sized voles, with a total length of , including the tail. Adults typically weigh anything from , with males being slightly larger than females, but the actual weight varies considerably with age, geography, and subspecies. The upper body is covered with fur of a dark brownish shade, again with some variation between individuals. The fur is paler on the flanks, and fades to grey or white on the underparts. The tail exhibits the same color variation, with the fur being dark brown to almost black on the upper surface and grey or white below. Montane voles possess
scent gland Scent gland are exocrine glands found in most mammals. They produce semi-viscous secretions which contain pheromones and other semiochemical compounds. These odor-messengers indicate information such as status, territorial marking, mood, and s ...
s on the hips, near the anus, and on the male genitalia. These glands increase in size in response to
testosterone Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of male reproductive tissues such as testes and prostate, as well as promoting secondary sexual characteristi ...
, and are therefore particularly large in adult males. At least some of these glands produce unique
fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, f ...
ester In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides ...
s, that may function in species recognition. Females have four pairs of teats, running from the chest to the groin.


Distribution and habitat

Montane voles are found in mountainous and other high elevation terrain in the western
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
and
Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by to ...
. Within this region they are generally found in drier climates than other species of vole, and in areas more dominated by grassland than by shrubs. Typical habitats include alpine meadows and grassy areas near streams or lakes; they are also often found in cropland or pasture. Fossils of montane voles have been recovered from as far back as the
Irvingtonian The Irvingtonian North American Land Mammal Age on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), spanning from 1.9 million – 250,000 years BP.
, when they appear to have been more widespread across what is now the southwestern United States. At least fourteen subspecies of montane vole are recognized: * ''M. m. montanus'' - eastern
California California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
and southern
Oregon Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
* ''M. m. arizonensis'' - eastern
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
and western
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...
* ''M. m. canescens'' - central
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
and southern
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, for ...
* ''M. m. codiensis'' - north western
Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to t ...
* ''M. m. dutcheri'' - central California * ''M. m. fucosus'' - southern
Nevada Nevada ( ; ) is a U.S. state, state in the Western United States, Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. N ...
* ''M. m. fusus'' - southern
Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...
* ''M. m. micropus'' - northern Nevada * ''M. m. nanus'' - widespread, from Washington and Oregon to
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columb ...
and Colorado * ''M. m. nevadensis'' - south western Nevada * ''M. m. pratincola'' - north western Montana * ''M. m. rivularis'' - southern and eastern
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...
* ''M. m. undosus'' - central Nevada * ''M. m. zygomaticus'' - north eastern Wyoming


Biology and behavior

Montane voles are herbivorous, although they may also eat small numbers of insects and other
arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...
s. The majority of their diet consists of forbs, supplemented by seeds, grasses, and fungi. One study in Colorado found that favored foods included
vetch ''Vicia'' is a genus of over 240 species of flowering plants that are part of the legume family (Fabaceae), and which are commonly known as vetches. Member species are native to Europe, North America, South America, Asia and Africa. Some other ...
and evening primrose. Predators include a range of hawks and owls, weasels, and even coyotes. Montane voles have been reported to form up to 80% of the diet of great horned owls in
Idaho Idaho ( ) is a U.S. state, state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Monta ...
. Montane voles have also been used in the laboratory in studies of African sleeping sickness, since they suffer similar symptoms to humans when infected with the parasite. Montane voles are nocturnal during the summer, but primarily diurnal during winter. They often inhabit abandoned gopher burrows, although they are also capable of digging their own. Typical burrows are in length, and reach a depth of , although there is considerable variation. Montane voles also construct nests, which are typically cup-shaped, although those used for raising young are globular and about in diameter. Males mark their territory with urine and dung and by rubbing their anal scent glands along the ground.


Reproduction

The breeding season begins in April or May, and continues until at least August. The start of the season is triggered by chemicals found in fresh spring grass, and coincides with the snowmelt. Since chemicals in older, late summer grass, depress the reproductive drive, the exact end of the season may vary from year to year, and some individuals have been reported to breed in midwinter in recent decades. Males mate with multiple females if the opportunity arises, and have no preference for unmated females over those that have previously mated. Females do not have regular estrus cycles, and their reproductive status is apparently induced by chemical signals from nearby males. Gestation lasts 21 days, and results in the birth of five to eight pups. The young are born blind and helpless, and are not capable of standing until four days after birth, around the time that they first begin to develop fur. Their eyes open after about ten days, and they are weaned at around fourteen days. The pups leave the nest a day or so after weaning, when the female begins to prepare for a new litter. The female may raise three to four litters in a year. Young born early in the year may reach sexual maturity in as little as four weeks, but those born in the fall do not do so until spring.


References

{{Authority control Microtus Mammals described in 1848 Taxonomy articles created by Polbot Taxa named by Titian Peale