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Overview

Brief Summary

Description

"The California Vole occurs throughout much of California and southwestern Oregon, with disjunct subspecies in the Mojave Desert, the White Mountain/Panamint ranges, and northern Baja California. California Voles construct surface runways and extensive underground burrows, and are active throughout the year, chiefly at dawn and dusk. Fresh vegetation clippings and fecal pellets are indicators of the Voles' presence. The size of individuals varies considerably over the range of the species, with males about 6 percent longer and 11 percent heavier than females. Local abundance is also highly variable."

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Mammal Species of the World
  • Original description: Peale, T.R., 1848.  U.S. exploring expeditions 1838, 1839, 1840, 1841, 1842 under the command of Charles Wilkes, U.S.N., Mammalogy and Ornithology, p. 44. Asherman and Co., Philadelphia, 8:1-338.
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Distribution

occurs (regularly, as a native taxon) in multiple nations

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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Western Oregon south through California to northern Baja California, Mexico.

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Range Description

Occurs from southwestern Oregon through central and western California (United States), and south into northern Baja California (Mexico). There are two disjunct populations in the Mohave Desert and White Mountain/Panamint ranges (California, USA).
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Geographic Range

Microtus californicus occurs along the Pacific Coast of North America, from central Oregon southward to northern Baja California. It occurs in the woodlands, shrublands and grasslands of these areas.

Biogeographic Regions: nearctic (Native )

  • Tamarin, R. 1985. Biology of New World Microtus. Shippensburg, Pennsylvania: Special Publication No.8 American Society of Mammalogists.
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Physical Description

Morphology

Physical Description

M. californicus present a lot of variation in size depending upon where they are found. Subspecies found in the south of the species range can be much larger than those found in the north.

In northern California, the total length veries between 139 ans 207 mm, of which only 39 to 68 mm is contributed by the tail. Males weigh between 33 and 81 g, averaging 52 g, and females can weigh between 30 and 68 g, averaging 47 g.

California voles are sexually dimorphic with the males being six percent longer and eleven percent heavier than females.

The coat of these animals is buffy brown, grayish brown or dark brown (blackish toward coast, reddish in desert) colored on top, with a reddish tinge down the middle of the back. The underside is blue-gray to white. The tail is bi-colored. The feet are pale, and the eyes are dark brown to black. M. californicus has 8 mammae.

This species can be distinguished from other voles by the following characteristics:

Microtus montanus occurs at higher elevations;

M. longicaudus is longer and its tail more bicolored;

M. townsendii has different cranial and dental features; and

M. oregoni is smaller and has only 5 toe pads.

Range mass: 38 to 108 g.

Range length: 139 to 214 mm.

Sexual Dimorphism: male larger

  • Ingles, L. 1965. Mammals of the Pacific States (CA, OR, WA). Stanford California: Stanford University Press.
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Size

Length: 21 cm

Weight: 100 grams

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Size in North America

Length:
Average: 172 mm
Range: 139-207 mm

Weight:
Average: 52 g males; 47 g females
Range: 33-81 g males; 30-68 g females
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Diagnostic Description

Differs from M. LONGICAUDUS in relatively shorter tail (averages less than 1/3 of total length in CALIFORNICUS, 1/3 or more of total length in LONGICAUDUS) and ridged skull. Differs from M. MONTANUS and M. TOWNSENDII in having paler feet (dusky in MONTANUS) and in having the incisive foramina not constricted posteriorly. Differs from M. OREGONI and PHENACOMYS (ARBORIMUS) in having 4 projections on the ligual side of M3 (last upper molar) rather than 3 projections (Ingles 1965); CALIFORNICUS also has longer fur than does M. OREGONI and has unrooted cheek teeth rather than rooted cheek teeth as in PHENACOMYS and CLETHRIONOMYS (Hall 1981).

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Ecology

Habitat

Comments: Fresh and brackish marshes; valley grasslands; dry grassy hillsides; upland meadows. Also found in agricultural areas. Occupies underground burrows and surface runways through grass.

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Habitat and Ecology

Habitat and Ecology
Inhabits grasslands and wet meadows at low elevations. Also, coastal wetlands and open oak savanna with good ground cover.

Systems
  • Terrestrial
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California voles inhabit areas of broad-leaved chaparral, oak woodlands, and grasslands along the Pacific Coast in northern Baja California to central Oregon. This species has a restricted distribution, which is possibly due to relic populations. It seems to utilize unusual habitats in California compared to other species of voles throughout the North American continent. Marshy ground, saltwater and freshwater locations, wet meadows, coastal wetlands and dry, grassy hillsides are the preferred macrohabitats of this species.

California voles are semifossorial. Their microhabitat consists of burrows, grass runways, and earth tunnels where piles of grass cuttings and fresh vegetation are often found. Piles of feces are also found in the runways.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral

Wetlands: marsh

Other Habitat Features: agricultural ; riparian

  • Burt, W., R. Grossenheider. 1980. Peterson Field Guide: Mammals. New York: Houghton Mifflin Co..
  • Whitaker, Jr., J. 1998. National Audobon Society, Field Guide to Mammals. New York: Chanticleer Press.
  • Wilson, D., S. Ruff. 1999. The Smithsonian book of North American mammals. Washington, D.C.: Smithsonian Institution Press.
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Migration

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

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Trophic Strategy

Comments: Eats green vegetation including grasses and sedges.

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Food Habits

M. californicus is herbvivorous and eat mostly grasses and roots, but also relies on sedges, fruits and forbs in certain areas. In the winter, the vole eats mostly roots and underground plant parts. Grain will also be eaten when available.

Plant Foods: leaves; seeds, grains, and nuts; fruit

Primary Diet: herbivore (Folivore , Frugivore , Granivore ); coprophage

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Associations

Ecosystem Roles

With their potential to reproduce rapidly, these voles are prey for many carnivore species. They form an important link in food webs. these voles also are hosts to many species of parasites.

Ecosystem Impact: keystone species

Commensal/Parasitic Species:

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Predation

Voles spend as little time exposed to the surface as possible. Underground tunnels are commonly used as are runways throughout tall grasslands. Unfortunately for the voles, the urine they use to communicate to each other is the way their diurnial predators track them and determine vole density. Through the raptors ability to see ultraviolet light, the florescent urine shows up in the runways and directs the predator to the prey's location. This could also explain how raptors are able to locate their vole prey even after population crashes.

There are a great number of vole predators, including coyotes, kestrels, hawks, weasles, kits, owls, snakes, herons, egrets, and ferrel cats. Because of their rapid reproduction and periody high population densities, these voles are a keystone prey species.

Known Predators:

  • Gee, H. February 2, 1995. In the eye of the kestrel. Nature, 373: 387.
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Known predators

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General Ecology

Populations increase and decline rapidly over a cycle of about 3-4 years. Predators include hawks, owls, weasels, and snakes.

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Life History and Behavior

Behavior

Communication and Perception

California voles communicate mostly through scent by depositing urine in areas of its runways as a tracking device. This tells the vole where it has been and who else inhabits a runway. Squeaks are also heard from adults during distress and young when communicating to the parent(s).

As with most other mammals, there is likely some visual communication as well.

Communication Channels: visual ; tactile ; acoustic ; chemical

Other Communication Modes: scent marks

Perception Channels: visual ; acoustic

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Cyclicity

Comments: Active throughout the year.

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Life Expectancy

Lifespan/Longevity

A successful lifespan for a vole will be up to a year, but the average lifespan is only a few months.

Typical lifespan

Status: wild:
1 to 12 months.

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Reproduction

Gestation lasts 21 days. May breed throughout the year but usually little or no reproduction in the summer dry season. Average litter size is 4.2, range 1-9. Young are weaned in 2 weeks.

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California voles seem mostly monogomous when populations aren't too dense. Dense populations or populations with unbalanced sex ratios will display polygynous traits. In these populations, males defend territories where grass is the staple diet, and females defend areas where fruits and forbs are the primary food source.

When polygyny is the prevailing mating system, females tend to have neighboring territories with their sisters and dispersing males may have little or no contact with close relatives.

Suppression of sexual maturation on the natal home range by the presence of the mother occurs. Kin recognition has little influence on inhibiting inbreeding, even in monogamous populations.

Adult males will cannibalize young that are not theirs. Females will also abort their litters if exposed to the phermones produced by unfamiliar males.

Mating System: monogamous ; polygynous

Ovulation in M. californicus is induced by copulation. This species experiences a post-partum estrus, and breeding can occur within fifteen hours after young are born. This allows up to 4 or 5 litters a season.

The breeding season is somewhat variable throughout the range of this species. Germination of annual grasses in the fall seems to initiate reproduction in some popultions. In other populations, where the climate is very Mediterranean, reproduction begins near the time of the first rains, and ends when the hot summer dries out the vegetation. In coastal populations, where the grasses stay green all year, and temperatures are mild, breeding can occur thorughout the year.

The gestation is twenty-two days. Litters of 1 to 11 young can be roduced, but the average is 4 or 5 young. Perennial grassland populations average about two embryos less than those in annual and mixed annual-perennial grassland populations. Young are altricial and weigh approximately 2.5g at birth. The pups are quickly weaned at two weeks old.

Females reach reproductive maturity by three weeks old, and the male at five weeks. Under some conditions, males can mature more rapidly, reaching sexual maturity by about 25 days of age. Sexual maturity can be supressed by the presence of the parents on the natal range. This allows the species to rapidly colonize when population densities are low, but to limit reproduction somewhat when populations are very dense.

Microtus species in general, appear to have a fairly plastic reproductive biology where the emphasis seems to be on the ability to produce the correct response (phenotypic) given the ecological conditions in which the population finds itself. Populations experience cyclic and annual fluctuations. The population typically grows for three to four years then declines rapidly in mild, temperate areas. In strongly seasonal habitats, the growth phase is two to five years.

Breeding interval: These voles can breed every three weeks under good conditions.

Breeding season: The breeding season seems to heavily rely on the wet season in non-coastal parts of California. In coastal populations, breeding is aseasonal.

Range number of offspring: 1 to 11.

Range gestation period: 22 (high) days.

Average weaning age: 2 weeks.

Average time to independence: 2 weeks.

Range age at sexual or reproductive maturity (female): 21 (low) days.

Range age at sexual or reproductive maturity (male): 25 to 42 days.

Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); induced ovulation ; fertilization ; viviparous ; post-partum estrous

As in all mammals, the female provides the young with milk for the duration of nursing. Although the young are altricial at birth, they grow quickly. Weaning occurs when the young are abut two weeks old.

In polygynous systems, females are the primary care givers, with neighboring territories being occupied by their sisters. In monogamous systems, males will participate in brood care. In these mating systems, males participate in parental care by gathering nesting materials and retreiving nestlings. Both males and females will display territorial traits, which helps to protect the young from intruders.

Nests are made with dried grasses and forbs and are located under logs or boards or under the earth's surface a few centimeters.

Parental Investment: altricial ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female)

  • Ingles, L. 1965. Mammals of the Pacific States (CA, OR, WA). Stanford California: Stanford University Press.
  • Krohne, D. 1982. The Bases of Intra- and Interpopulational Reproductive Variation and their Demographic Consequences in the California Vole. Ann Arbor, Michigan: University Microfilms International.
  • Tamarin, R. 1985. Biology of New World Microtus. Shippensburg, Pennsylvania: Special Publication No.8 American Society of Mammalogists.
  • Tamarin, R., R. Ostfeld, S. Pugh, G. Bujalska. 1990. Social Systems and Population Cycles in Voles. Boston: Birkhauser Verlag.
  • Wilson, D., S. Ruff. 1999. The Smithsonian book of North American mammals. Washington, D.C.: Smithsonian Institution Press.
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Conservation

Conservation Status

National NatureServe Conservation Status

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

Reasons: Common in many areas from Oregon through California to northern Baja California.

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Álvarez-Castañeda, S.T., Castro-Arellano, I., Lacher, T. & Vázquez, E.

Reviewer/s
McKnight, M. (Global Mammal Assessment Team) & Amori, G. (Small Nonvolant Mammal Red List Authority)

Contributor/s

Justification
This species is listed as Least Concern in view of its wide distribution, presumed large population, and because it is unlikely to be declining at nearly the rate required to qualify for listing in a threatened category.
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These voles are quite common and so are not a big conservation concern. Local abundances can vary from year to year, but overall the population cycle seems stable. However, because thes voles are so important to their ecosystem, it is worthwile to keep an eye on their population cycles and habitat availability, so that other species which depend upon them for food, and whose population status may be less secure, are safeguarded.

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Status

Two subspecies (M. californicus mohavensis, the Mojave River vole, and M. californicus scirpensis, the Amargosa vole) are Vulnerable; a third subspecies (M. californicus vallicola, the Owens Valley California vole) is Near Threatened.
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Population

Population
Populations tend to be stable in coastal areas (around 200 individuals/ha), but in more strongly seasonal habitats densities vary dramatically over 2 to 5-year cycles, ranging from virtual absence to typical peaks of 450 individuals/ha.

Population Trend
Stable
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Threats

Major Threats
None to the species as a whole.

However, 4 subspecies (2 disjunct populations previously mentioned, one in northern Baja California, and one in the Los Angeles area) are of conservation concern.
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Management

Conservation Actions

Conservation Actions
There are no known conservation measures specific to this species. However, there are several protected areas within its range.

M. c. scirpensis is a federally Endangered species in the United States, with an extant recovery plan. In California, there are several subspecies of conservation concern: M. c. mohavensis, M. c. sanpabloensis, M. c. scirpensis, M. c. stephensi, and M. m. vallicola.
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Relevance to Humans and Ecosystems

Benefits

Economic Uses

Comments: May cause damage to crops, orchards, vineyards, etc.

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Economic Importance for Humans: Negative

During peak population times, numbers of voles are said to exceed to the hundreds per acre, and up to a thousand per hectare, causing crop problems in areas where farms coincide with vole habitat.

Negative Impacts: crop pest

  • Zim, H., D. Hoffmeister. 1955. Golden Guide: Mammals. New York: Golden Press.
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Economic Importance for Humans: Positive

Although there is apparently no direct benefit of this species for humans, it should be noted that without this keystone species, many of the larger animals that people enjoy watching, such as hawks, kestrels, coyotes and foxes, would not be able to exist at such high densities, and therefore would be a much less visible part of local ecosystems.

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Wikipedia

California vole

The California vole (Microtus californicus) is a type of vole[2] which lives throughout much of California and part of southwestern Oregon. It is also known as the California meadow mouse. It averages 172 mm (6.8 in) in length although this length varies greatly between subspecies.

Description[edit]

The California vole is a medium-sized vole, and a typical member of its group in appearance. Males range from 152 to 196 mm (6.0 to 7.7 in) in head-body length, with a 42 to 58 mm (1.7 to 2.3 in) tail. Females are significantly smaller at 149 to 182 mm (5.9 to 7.2 in) in length with a 38 to 53 mm (1.5 to 2.1 in) tail. Males weigh from 41 to 81 g (1.4 to 2.9 oz), and females from 36 to 63 g (1.3 to 2.2 oz).[3] Variation between different subspecies, though, is considerable, with the southern subspecies tending to be larger than those found further north.[4]

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 and feet are grey in color, with a patch of white fur near the anus.[3] 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 glands on the hips, which are used to mark their trackways. Females have four pairs of teats, two in the chest, and two closer to the groin.[4]

Distribution and habitat[edit]

The California vole is found from El Rosario in Baja California in the south, through much of California and as far as Eugene, Oregon 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 habitats, from wet coastal marshland to dry uplands and savannah.[5]

Subspecies[edit]

Seventeen subspecies are currently recognized,[4] some of which are protected.[6] They include:

Ecology[edit]

A juvenile red-tailed hawk eating a California vole

The California vole is herbivorous, feeding mainly on grasses and sedges, supplemented by other flowering herbs. Preferred foods include wild oats, ryegrass, and brome grass, although all of these are introductions from Europe, and therefore cannot represent the animal's original diet.[7] They can become an agricultural pest, causing widespread damage especially to fields of artichokes, but also to crops such as alfalfa, potatoes, and asparagus.[4]

Because the California vole is relatively common and widespread, it has numerous natural predators, including hawks, owls, egrets, long-tailed weasels, coyotes, skunks, and garter snakes.[4]

Behavior[edit]

California voles are crepuscular or nocturnal. 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 103 square metres (1,110 sq ft) for males and 68 square metres (730 sq ft) 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.[8] Although they also sometimes use abandoned gopher tunnels, burrows dug by the voles themselves are blind-ending and range from 1.5 to 12 m (4.9 to 39.4 ft) in length. The voles construct nests of dried grass within their burrows; these have a single entrance, and are typically between 7 and 15 cm (2.8 and 5.9 in) below the surface.[9]

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.[4]

Reproduction[edit]

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 as some other voles. Copulation can be prolonged and repeated, and is followed by formation of a copulatory plug and by induced ovulation. Gestation 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.[4]

The young are born hairless and blind, weighing an average of 2.8 g (0.099 oz). 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.[4] The lifespan is correspondingly short, with individuals living for less than a year, even in the absence of predators.

Evolution[edit]

Fossils of members of the Microtus genus 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.[10] Genetic evidence suggests the closest extant relative of the California vole is most likely the Mexican vole, 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.[11]

References[edit]

  1. ^ Álvarez-Castañeda, S.T., Castro-Arellano, I., Lacher, T. & Vázquez, E. (2008). Microtus californicus. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 11 June 2009. Database entry includes a brief justification of why this species is of least concern.
  2. ^ Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  3. ^ a b B.J. Verts; L.N. Carraway (1998). Land Mammals of Oregon. Berkeley: University of California Press. 
  4. ^ a b c d e f g h Cudworth, N.L. & Koprowski, J.L. (2010). "Microtus californicus (Rodentia: Cricetidae)". Mammalian Species 42 (1): 230–243. doi:10.1644/868.1. 
  5. ^ Heske, E.J. & Lidicker, W.Z. (1999). Wilson, D.E. & Ruff, S., ed. The Smithsonian Book of North American Mammals. Washington, D.C.: Smithsonian Institution Press. pp. 626–628. ISBN 1-56098-845-2. 
  6. ^ CDFG Special Animals List, February 2008
  7. ^ Batzli, G.O. & Pitelka, F.A. (1971). "Condition and diet of cycling populations of the California vole, Microtus californicus". Journal of Mammalogy 52 (1): 141–163. JSTOR 1378438. 
  8. ^ Heske, E.J. (1987). "Spatial structuring and dispersal in a high density population of the California vole Microtus californicus". Ecography 10 (2): 137–148. doi:10.1111/j.1600-0587.1987.tb00750.x. 
  9. ^ Stark, H.E. (1963). "Nesting habits of the California vole, Microtus californicus, and microclimate factors affecting its nests". Ecology 44 (4): 663–669. JSTOR 1933012. 
  10. ^ Bell, J. & Bever, J.S. (2006). [371%3ADASOTM2.0.CO%3B2 "Description and significance of the Microtus (Rodentia: Arvicolinae) from the type Irvington fauna, Alameda County, California"]. Journal of Vertebrate Paleontology 26 (2): 371–380. doi:10.1671/0272-4634(2006)26[371:DASOTM]2.0.CO;2. 
  11. ^ Conroy, C.J. & Neuwald, J.L. (2008). "Phylogeographic study of the California vole, Microtus californicus". Journal of Mammalogy 89 (3): 755–767. doi:10.1644/07-MAMM-A-189R1.1. 
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Names and Taxonomy

Taxonomy

Comments: Phylogeographic study using mitochondrial and nuclear DNA suggested the existence of two phylogeographic groups that are largely discordant with the boundaries of 17 currently recognized subspecies; further study may indicate that these two clades represent different species (Conroy and Neuwald 2008). Clade divergence may be associated with ecological differences (Conroy and Neuwald 2008).

Nearest specific relative is unclear (see Musser and Carleton, in Wilson and Reeder 1993, 2005).

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