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The California vole (''Microtus californicus'') is a type 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 ...
which lives throughout much of
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 part of southwestern
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 ...
. It is also known as the "California meadow mouse", a misnomer as this species is a vole, not a mouse. It averages in length although this length varies greatly between subspecies.


Description

The California vole is a medium-sized vole, and a typical member of its group in appearance. Males range from in head-body length, with a tail. Females are significantly smaller at in length with a tail. Males weigh from , and females from . Variation between different subspecies, though, is considerable, with the southern subspecies tending to be larger than those found further north. The body is covered with cinnamon to tawny olive fur, ticked with occasional darker hairs, and fading to a medium grey on the underside. The tail is black above and grey below. The
whiskers Vibrissae (; singular: vibrissa; ), more generally called Whiskers, are a type of stiff, functional hair used by mammals to sense their environment. These hairs are finely specialised for this purpose, whereas other types of hair are coarse ...
and feet are grey in color, with a patch of white fur near the
anus The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, ...
. Between subspecies, those native to more highland habitats tend to be more reddish in color, and those in marshier environments tend to be darker. Males have a pair of
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, which are used to mark their trackways. Females have four pairs of
teat A teat is the projection from the mammary glands of mammals from which milk flows or is ejected for the purpose of feeding young. In many mammals the teat projects from the udder. The number of teats varies by mammalian species and often corr ...
s, two in the chest, and two closer to the groin.


Distribution and habitat

The California vole is found from El Rosario in
Baja California Baja California (; 'Lower California'), officially the Free and Sovereign State of Baja California ( es, Estado Libre y Soberano de Baja California), is a state in Mexico. It is the northernmost and westernmost of the 32 federal entities of Mex ...
in the south, through much of
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 as far as Eugene,
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 ...
in the north. It is, however, absent from most of the deserts of southeastern California and from the extreme northeastern and northwestern corners of the state. It inhabits a range of different
grassland A grassland is an area where the vegetation is dominated by grasses ( Poaceae). However, sedge ( Cyperaceae) and rush ( Juncaceae) can also be found along with variable proportions of legumes, like clover, and other herbs. Grasslands occur na ...
habitats, from wet coastal
marsh A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found ...
land to dry uplands and
savannah A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
.


Subspecies

Seventeen subspecies are currently recognized, some of which are protected.CDFG Special Animals List, February 2008
They include: * ''M. c. californicus'' -
San Francisco San Francisco (; Spanish for " Saint Francis"), officially the City and County of San Francisco, is the commercial, financial, and cultural center of Northern California. The city proper is the fourth most populous in California and 17t ...
region * ''M. c. equivocatus'' - Baja California * ''M. c. aestuarinus'' - central California * ''M. c. constrictus'' -
Humboldt County, California Humboldt County () is a county located in the U.S. state of California. As of the 2020 census, the population was 136,463. The county seat is Eureka. Humboldt County comprises the Eureka–Arcata– Fortuna, California Micropolitan Statist ...
* ''M. c. eximus'' - Oregon and north-central California * ''M. c. grinelli'' -
Sierra de Juárez The Sierra de Juárez, also known as the Sierra Juarez, is a mountain range located in Tecate Municipality and northern Ensenada Municipality, within the northern Baja California state of northwestern Mexico. It is a major mountain range in the ...
, Baja California * Monterey vole, ''M. c. halophilus'' -
Monterey Bay Monterey Bay is a bay of the Pacific Ocean located on the coast of the U.S. state of California, south of the San Francisco Bay Area and its major city at the south of the bay, San Jose. San Francisco itself is further north along the coast, by ...
, California * ''M. c. huperuthrus'' - Baja California * ''M. c. kernensis'' -
Kern County Kern County is a county located in the U.S. state of California. As of the 2020 census, the population was 909,235. Its county seat is Bakersfield. Kern County comprises the Bakersfield, California, Metropolitan statistical area. The county sp ...
, California * ''M. c. mariposae'' - east-central California * Mojave River vole, ''M. c. mohavensis'' (
CDFG special concern A species of special concern (SSC or CSC) is a protective legal designation assigned by the California Department of Fish and Wildlife (CDFW) to wildlife species that are at risk. An SSC is a species, subspecies, or distinct population of an ani ...
) -
Mojave Desert The Mojave Desert ( ; mov, Hayikwiir Mat'aar; es, Desierto de Mojave) is a desert in the rain shadow of the Sierra Nevada mountains in the Southwestern United States. It is named for the indigenous Mojave people. It is located primarily ...
* ''M. c. paludicola'' -
Alameda County Alameda County ( ) is a county located in the U.S. state of California. As of the 2020 census, the population was 1,682,353, making it the 7th-most populous county in the state and 21st most populous nationally. The county seat is Oakland. Alam ...
, California * ''M. c. sanctidiegi'' - southwestern California * San Pablo vole, ''M. c. sanpabloensis'' (
CDFG special concern A species of special concern (SSC or CSC) is a protective legal designation assigned by the California Department of Fish and Wildlife (CDFW) to wildlife species that are at risk. An SSC is a species, subspecies, or distinct population of an ani ...
) -
Contra Costa County ) of the San Francisco Bay , subdivision_type = Country , subdivision_name = United States , subdivision_type1 = State , subdivision_name1 = California , subdivision_type2 ...
, California * Amargosa vole, ''M. c. scirpensis'' (Federal and State
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...
) -
Panamint Range The Panamint Range is a short rugged fault-block mountain range in the northern Mojave Desert, within Death Valley National Park in Inyo County, eastern California. Dr. Darwin French is credited as applying the term Panamint in 1860 during his ...
, California * South Coast marsh vole, ''M. c. stephensi'' (
CDFG special concern A species of special concern (SSC or CSC) is a protective legal designation assigned by the California Department of Fish and Wildlife (CDFW) to wildlife species that are at risk. An SSC is a species, subspecies, or distinct population of an ani ...
) -
Los Angeles Los Angeles ( ; es, Los Ángeles, link=no , ), often referred to by its initials L.A., is the largest city in the state of California and the second most populous city in the United States after New York City, as well as one of the world ...
region * Owens Valley vole, ''M. c. vallicola'' (
CDFG special concern A species of special concern (SSC or CSC) is a protective legal designation assigned by the California Department of Fish and Wildlife (CDFW) to wildlife species that are at risk. An SSC is a species, subspecies, or distinct population of an ani ...
) - White Mountains, California


Ecology

The California vole is
herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...
, feeding mainly on
grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns a ...
es and
sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus '' Carex'' ...
s, supplemented by other flowering herbs. Preferred foods include
wild oat ''Avena'' is a genus of Eurasian and African plants in the grass family. Collectively known as the oats, they include some species which have been cultivated for thousands of years as a food source for humans and livestock. They are widespread ...
s,
ryegrass ''Lolium'' is a genus of tufted grasses in the bluegrass subfamily (Pooideae). It is often called ryegrass, but this term is sometimes used to refer to grasses in other genera. They are characterized by bunch-like growth habits. ''Lolium'' i ...
, and
brome grass ''Bromus'' is a large genus of grasses, classified in its own tribe Bromeae. They are commonly known as bromes, brome grasses, cheat grasses or chess grasses. Estimates in the scientific literature of the number of species have ranged from 100 ...
, although all of these are introductions from Europe, and therefore cannot represent the animal's original diet. They can become an agricultural pest, causing widespread damage especially to fields of
artichoke The globe artichoke (''Cynara cardunculus'' var. ''scolymus'' ),Rottenberg, A., and D. Zohary, 1996: "The wild ancestry of the cultivated artichoke." Genet. Res. Crop Evol. 43, 53–58. also known by the names French artichoke and green articho ...
s, but also to crops such as
alfalfa Alfalfa () (''Medicago sativa''), also called lucerne, is a perennial flowering plant in the legume family Fabaceae. It is cultivated as an important forage crop in many countries around the world. It is used for grazing, hay, and silage, as ...
,
potato The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern Uni ...
es, and
asparagus Asparagus, or garden asparagus, folk name sparrow grass, scientific name ''Asparagus officinalis'', is a perennial flowering plant species in the genus '' Asparagus''. Its young shoots are used as a spring vegetable. It was once classified in ...
. Because the California vole is relatively common and widespread, it has numerous natural predators, including
hawk Hawks are birds of prey of the family Accipitridae. They are widely distributed and are found on all continents except Antarctica. * The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks and others. This subfa ...
s,
owl Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...
s,
egret Egrets ( ) are herons, generally long-legged wading birds, that have white or buff plumage, developing fine plumes (usually milky white) during the breeding season. Egrets are not a biologically distinct group from herons and have the same buil ...
s, long-tailed weasels,
coyote The coyote (''Canis latrans'') is a species of canine native to North America. It is smaller than its close relative, the wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological nich ...
s,
skunk Skunks are mammals in the family Mephitidae. They are known for their ability to spray a liquid with a strong, unpleasant scent from their anal glands. Different species of skunk vary in appearance from black-and-white to brown, cream or gin ...
s,
mountain lion The cougar (''Puma concolor'') is a large cat native to the Americas. Its range spans from the Canadian Yukon to the southern Andes in South America and is the most widespread of any large wild terrestrial mammal in the Western Hemisphere. ...
s and
garter snake Garter snake is a common name for generally harmless, small to medium-sized snakes belonging to the genus ''Thamnophis'' in the family Colubridae. Native to North and Central America, species in the genus ''Thamnophis'' can be found from the sub ...
s.


Behavior

California voles are
crepuscular In zoology, a crepuscular animal is one that is active primarily during the twilight period, being matutinal, vespertine, or both. This is distinguished from diurnal and nocturnal behavior, where an animal is active during the hours of dayli ...
or
nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...
. However, they spend much of their time below ground, using burrows connected by above-ground runways they use to find food. Home ranges are relatively small, with the animals rarely venturing far from their burrows; averages of for males and for females have been reported. The larger ranges of males overlap with the ranges of several nearby females, but they are generally aggressive only towards other nearby males, clawing and biting any intruders. Although they also sometimes use abandoned gopher tunnels, burrows dug by the voles themselves are blind-ending and range from in length. The voles construct nests of dried grass within their burrows; these have a single entrance, and are typically between below the surface. The voles are active above ground primarily to find food, reaching the seeds on high grasses by standing on their hind legs and clipping the stems with their teeth. They often carry the food back to their burrow to eat it, although they do not hoard food or hibernate through the winter. California voles are often found in groups of a single male, one or more females, and a number of young, and the male may assist the female in construction of her nest before she gives birth. California voles are reasonably strong swimmers, and may use this tactic to attempt to escape from predators.


Reproduction

California voles are able to breed almost year-round, although most breeding occurs during the middle of the wet season, from March to April. Males may breed with more than one female, although the species is not as strongly
polygynous Polygyny (; from Neoclassical Greek πολυγυνία (); ) is the most common and accepted form of polygamy around the world, entailing the marriage of a man with several women. Incidence Polygyny is more widespread in Africa than in any ...
as some other voles. Copulation can be prolonged and repeated, and is followed by formation of a
copulatory plug A mating plug, also known as a copulation plug, sperm plug, vaginal plug, or sphragis (Latin, from Greek σφραγίς ''sphragis'', "a seal"), is gelatinous secretion used in the mating of some species. It is deposited by a male into a female g ...
and by
induced ovulation Ovulation induction is the stimulation of ovulation by medication. It is usually used in the sense of stimulation of the development of ovarian follicles Ovulation Induction Retrieved on Mars 7, 2010 to reverse anovulation or oligoovulation. Sco ...
.
Gestation Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during pr ...
lasts three weeks and results in the birth of up to 10 young, with four or five being most common. The female is ready to breed again with 15 hours of giving birth, and may give birth to several litters over the course of her life. The young are born hairless and blind, weighing an average of . They begin to grow fur within five days of birth, and their eyes open at 9 days, although they are capable of sensing light before this. The young are weaned at around two weeks of age, and have a full set of adult teeth by three weeks. Females reach sexual maturity after as little as three weeks, while males become sexually mature after six weeks. The lifespan is correspondingly short, with individuals living for less than a year, even in the absence of predators.


Evolution

Fossils of members of the genus ''
Microtus ''Microtus'' is a genus of voles found in North America, Europe and northern Asia. The genus name refers to the small ears of these animals. About 62 species are placed in the genus. They are stout rodents with short ears, legs and tails. They ea ...
'' are known from California as far back as 1.2 million years ago, although it is unclear whether these represent California voles specifically, or a related, possibly extinct, species. Genetic evidence suggests the closest extant relative of the California vole is most likely the
Mexican vole The Mexican vole (''Microtus mexicanus'') is a species of vole. The Hualapai Mexican vole (''M. m. hualapaiensis'') was formerly recognized as a subspecies and was a protected taxon under the United States Endangered Species Act until 2017. Sever ...
, ''Microtus mexicanus'', and the species is known to be able to produce infertile hybrids with other closely related species, such as the montane vole. Indeed, matings between northern and southern subspecies of California vole do not always produce fertile offspring, with male hybrids in particular typically being infertile. This may indicate some of the subspecies are in the process of diverging into separate species, and it has even been proposed that the California vole may already represent two different species.


References

{{Taxonbar, from=Q1766467 California Vole Mammals of the United States Mammals of Mexico Rodents of North America California vole California vole California vole California vole California vole California vole Mammals described in 1848 Least concern biota of the United States Taxa named by Titian Peale