Montane Vole (Microtus montanus)

Q: Is a montane vole the same thing as a meadow vole?

No. They are two different species, Microtus montanus and Microtus pennsylvanicus, and their ranges genuinely overlap across the Mountain West. Montana's Department of Agriculture says the only reliable way to tell them apart is the middle molar of the upper jaw, five islands for meadow vole and four for montane, and warns against relying on color or size at all. In the field, read the ground instead: montane vole holds dry grassland and sagebrush-steppe, and only moves onto wet meadow and marsh at high elevation where the meadow vole is absent.

Q: Why does my mountain lawn look destroyed the moment the snow melts?

Because voles never stopped. They do not hibernate. They spend the whole winter active under the snowpack, wearing runways through the grass and gnawing bark at whatever height the snow lets them reach. The snow hides all of it until it goes, and then the entire network shows up at once. That is also why girdling damage appears at a consistent height around a trunk: that height is the snow line.

Q: Do voles carry disease?

They can carry plague, tularemia and hantavirus organisms, but Montana's Department of Agriculture and Utah State Extension both state that voles rarely transmit disease to people, because contact is infrequent and voles stay outdoors instead of moving into homes the way deer mice and house mice do. There is one species-specific finding worth knowing: in a multi-year survey in Jackson Hole and Grand Teton National Park, with serology run by the Centers for Disease Control and Prevention, montane vole was one of only three species out of 18 rodent species screened that tested hantavirus-seropositive. No published record links that vole-associated strain to a human case. Never handle a vole, live or dead, without gloves.

Q: Is it legal to kill voles on my property?

In Colorado, yes, when they are actually causing a problem. Colorado Parks and Wildlife lists montane vole as protected nongame wildlife and then specifically allows voles to be captured or killed when creating a nuisance or causing property damage. Wyoming's nongame mammal list names meadow vole but not montane vole, and published guidance does not settle what that means, so check with Game and Fish there before trapping or relocating. Montana runs a state vertebrate pest program that publishes vole control guidance with no permit or season attached to the animal. Idaho lists the species present and native with a secure state rank.

Q: Why do vole numbers explode in some years and vanish in others?

Because montane voles read the chemistry of the grass rather than the calendar. A compound in sprouting green grass called 6-MBOA switches their breeding on, and compounds that build up in cured, dormant vegetation switch it off. That was discovered in this species: two 1981 papers in Science fed 6-MBOA to nonbreeding winter voles and had pregnant females three weeks later, while controls stayed reproductively inactive. Add a 21-day gestation, sexual maturity in as little as four to five weeks in a wet year, and conception immediately after birth, and one good spring can multiply a population. Published cycle lengths range from every two to five years up to every four to eight, and a 17-year study found five straight years with no cycle at all, so the peaks are real but the schedule is not predictable.

Q: When should I call a professional instead of setting traps myself?

Montana's Department of Agriculture gives an actual threshold for producers: consider control when colonies, identified by groups of one-inch holes, reach four to five per acre, or when trap catch rate exceeds 10 percent, meaning roughly four voles from 36 traps overnight. Beyond that, call when the asset at risk is a crop or planting rather than a lawn, since restricted-use products require a licensed applicator, and call in the fall rather than in spring, because the control window is before the snow arrives, not after the damage appears.

Photo not yet available for Montane Vole

Across the Mountain West the montane vole shares ground with the meadow vole, and the only reliable way to tell the two apart is a tooth. Montana's Department of Agriculture says it in plain language: the middle molar of the upper jaw carries five islands in a meadow vole and four in a montane vole. Nobody is doing that in a yard. What you can read instead is the ground, because the two species sort by habitat. Montane vole holds the dry stuff, sagebrush-steppe and dry grassland, and only moves onto wet meadow and marsh at high elevation where the meadow vole is not there to hold it. There is a second reason this animal is worth knowing by name. It is the species in which science worked out why voles boom and crash. In 1981 two papers in Science isolated a compound in sprouting green grass, 6-MBOA, and showed it switches montane vole reproduction on. Feed it to nonbreeding winter voles and three weeks later the females are pregnant. Compounds in cured, dormant vegetation switch the same system off. That is the engine behind an irrigated hay valley going from quiet to overrun in a single wet spring, and it was measured in this animal first.

Seasonal Timeline

Montane voles do not hibernate and are active day and night in every month of the year. What changes across the Mountain West is when the damage becomes visible, and that tracks snow. At higher elevations and in mountain valleys the animals work all winter under the snowpack and the whole runway network appears at once at snowmelt, which is why calls cluster from December through March and spike again in April. Lower, drier valley floors with less reliable snow cover behave differently, closer to a spring and fall visibility pattern. For anyone farming irrigated hay or alfalfa, the operational window is earlier than the lawn-damage window: Montana's Department of Agriculture puts the most critical monitoring point at early spring, pre-thaw, because most crop damage happens in the earliest stages of crop development.

Peak, Every regionDec–Mar

JanFebMarAprMayJunJulAugSepOctNovDec

Montane voles do not hibernate and are active day and night in every month of the year. What changes across the Mountain West is when the…

The December to March peak is a visibility window, not an activity window. Montane voles are active in every month and do not hibernate. Colorado State Extension and Montana's Department of Agriculture agree on that. What the December to March peak actually describes is snow cover: at mountain-valley and higher elevations, voles spend the winter working under the snowpack, wearing runways through the grass and girdling bark at whatever height the snow lets them reach, and none of it is visible until the snow goes.

This region genuinely splits, and rounding it to one set of months hides something real. Higher-elevation and mountain-valley communities follow the snow-driven pattern above. Lower, drier valley floors with less reliable snow cover look more like a spring and fall visibility pattern instead. A single calendar across Colorado, Wyoming, Montana and Idaho is a compromise across a very wide elevation range, and it should be read as one.

Cycle timing is a separate question, and the published answers do not agree. Montana's Department of Agriculture gives peaks every two to five years and adds that "these cycles are not predictable." Colorado State Extension gives every three to four years. The federal wildlife damage research review gives three to five. UC IPM gives every four to eight. A 17-year live-trapping study of this species in semiarid grassland recorded peak densities in six of those years, fluctuations of three to four years that "were not always present," and then five straight years of low numbers with no cycle at all. The full spread runs from two to eight years. The peaks are real and the schedule is not.

Where They're Found

Montane vole lives across the Mountain West: Colorado, Wyoming, Montana and Idaho. The species is confirmed in all four. Montana ranks it S5, common to uncommon across montane and to a limited extent valley habitats, found through the western half of the state. Idaho lists it present and native at a state rank of S4. Colorado names montane vole by name in its own nongame wildlife regulation. Wyoming has long-term study populations of this species that have been monitored inside Grand Teton National Park since 1971.

The habitat rule is the most useful thing to know, because it is the only field-usable way to separate this animal from the meadow vole where both occur. Montana's Natural Heritage Program puts montane vole in usually dry grassland or sagebrush-grasslands, and adds that it will use wet meadows and marshes at high elevations when the meadow vole is absent. Read that carefully: it is a statement about competition. Where the two species share a valley, the meadow vole holds the wet sedge and streamside ground and the montane vole works the dry ground. Where the meadow vole is missing, the montane vole takes the wet ground too.

Not every source describes it as a dry-ground animal. The National Park Service's Yellowstone account describes montane vole in moist mountain meadows with abundant grass and grassy sagebrush communities, also common in riparian areas, at all elevations. The American Society of Mammalogists gives damp grassland, often near streams or marshes. Montana's Department of Agriculture splits the difference with dry grasslands to moist meadows, from valleys to tundra. The competition between the two species reconciles most of that, and Grand Teton field work found sites where the long-tailed vole rather than the montane vole predominates, so fine-scale sorting inside apparently similar habitat is real. What a reader should take away is that dry grassland and sagebrush-steppe is the working default, not a guarantee.

On the ground, the animal lives in cover. Dense ground cover of grass and litter, with underground tunnel systems whose open entrances run roughly one to two inches across, connected by one to two inch wide surface runways worn beneath vegetation and litter. In farm country that means perennial grassland, set-asides, field margins, ditch banks, rights-of-way, waterways, orchards, hay and alfalfa fields, windbreaks, lawns, nurseries, golf courses and cemeteries. Home range is about a quarter acre, and one tunnel system may hold several adults and numerous young. Cover is the limiting factor before moisture is: a minimum vegetation height and density has to be there before numbers can climb at all.

The range runs well past those four states. Full published range is the Cascade, Sierra Nevada and Rocky Mountain ranges from south-central British Columbia south to east-central California, southern Utah and north-central New Mexico, with disjunct populations in southern Nevada, east-central Arizona and west-central New Mexico. Utah State Extension lists it as one of five vole species in Utah. In California it is one of only two economically important vole species, in the higher Sierra and the northeastern plateau counties, and UC IPM attributes most Klamath Basin potato damage to it specifically. Washington State University Extension names it as one of two vole species that commonly cause damage in eastern Washington.

Alaska and Hawaii are both confirmed absent. No source places Microtus montanus in Alaska, and the published northern limit of the species is south-central British Columbia. Alaska's own voles are different species. Hawaii has no vole of any kind.

Related Pests

California Vole

Creeping Vole (Oregon Vole)

Deer Mouse

Meadow Vole

Northern Pocket Gopher

Townsend's Vole

Vole (Prairie Vole / Meadow Vole)

Life Cycle

The reason montane vole numbers explode is chemical, and it was discovered in this species. In 1981 two back-to-back papers in Science isolated 6-methoxybenzoxazolinone, 6-MBOA, a compound present in the young green growing shoots of grasses, and showed it stimulates reproductive activity in Microtus montanus. The companion experiment is the striking one. Nonbreeding winter populations of montane voles were fed rolled oats coated with 6-MBOA. After three weeks those populations showed a high incidence of pregnancy in females and testicular hypertrophy in males, while control populations fed oats coated only with solvent showed no reproductive activity at all. The same group later showed the reverse: naturally occurring cinnamic acids and vinylphenols, which build up in cured and dormant vegetation, inhibit reproduction in this species, cutting uterine weight, blocking follicular development, and stopping breeding.

Put together with the reproductive arithmetic, that explains a boom year without invoking anything mysterious. Gestation is 21 days. Sexual maturity is nominally 35 to 40 days but arrives at four to five weeks in a wet season. Females are induced ovulators with a postpartum estrus, so conception can follow a birth immediately. The animal is not counting daylight, it is reading the chemistry of the grass, which is why an early wet spring in a mountain valley puts an entire population into breeding condition at once and a drought year shuts it down.

Litters per year is genuinely disputed. Montana's Department of Agriculture gives one to five litters per female per year. UC IPM gives five to ten in irrigated agricultural settings. The federal wildlife damage review gives five or more. Colorado State Extension's PlantTalk landscape guidance gives as many as five litters of three to five young. The low figures are field estimates from dryland Montana and the high figures come from irrigated cropland, and both are probably right for their own ground. The counterweight in every source is lifespan: Colorado State Extension says voles usually live between two and six months, Montana says many die within the first month and voles rarely reach 16 months, and the federal review puts annual mortality above 70 percent.

Newborn Pup

Newborn pup. Born blind and helpless after a gestation of 21 days. Montana's state figure is an average of five or six young per litter; federal and extension sources give three to six with a maximum of 11. Montane voles are induced ovulators with no regular cycle and a postpartum estrus, so a female can conceive again immediately after giving birth.

Juvenile

Juvenile. Sexual maturity at 35 to 40 days as a general figure, but in a good year it comes far faster. A study of two montane meadow sites in northwestern Wyoming found first-cohort females breeding at four to five weeks of age in a wet 1987 season and second-cohort females at seven to eight weeks. In the 1988 drought year at the same sites, very few females reached sexual maturity at all. That swing is the whole boom-bust story in one measurement.

Adult

Adult. Roughly 5 to 8.5 inches nose to tail tip depending on the source, at about 1.2 to 3.2 ounces. Blackish brown to grayish-brown above with a gray cast, pale buffy sides, whitish to silvery underparts, dusky feet, and a short bi-colored tail about one third the length of head and body. Active day and night in every month, no hibernation. Home range about a quarter acre. Lifespan is short: many die within the first month, and voles rarely live past 16 months.

Montane vs. Meadow Vole

Two different animals sharing the same states. Montane vole is Microtus montanus; meadow vole is Microtus pennsylvanicus. Montana's Department of Agriculture states the only reliable physical distinction is the middle molar of the upper jaw, five islands for meadow vole and four for montane, and warns explicitly against relying on color or size, since vole hair varies within a species and weight swings seasonally. The field substitute is habitat: montane vole on dry grassland and sagebrush-steppe, meadow vole on the wet sedge and streamside ground, with montane vole taking wet meadow only at high elevation where meadow vole is absent.

Vole vs. Pocket Gopher Signs

Not the animal, the evidence, and this is the test that saves money. A vole leaves no mound at all: one to two inch wide runways worn through matted grass, open holes one to two inches across, clipped vegetation and scat in the runs, and spongy soil underfoot. A pocket gopher leaves a fan-shaped mound of fine dry soil with a plugged, off-center entrance and no visible hole, over tunnels 2.5 to 3.5 inches across sitting 4 to 18 inches down. After a mountain winter the gopher adds one more tell that voles never produce: eskers, long snake-like ropes of soil lying on the lawn where the animal packed excavated dirt into tunnels in the snowpack and the snow melted out from around it.

Identification

You cannot tell it from a meadow vole

The honest headline is that you cannot separate a montane vole from a meadow vole by looking at it. Montana's Department of Agriculture states it directly: the only reliable way to tell them apart is by examining the middle molar of the upper jaw, which carries five islands in a meadow vole and only four in a montane vole. The same bulletin warns against relying on color or size, because vole hair varies within a single species and weight swings seasonally as animals fatten for winter. Both species carry four pairs of mammary glands, so that character does not separate them either, only prairie vole with three.

Use the ground instead

The two species sort by habitat. Montana's Natural Heritage Program places montane vole in usually dry grassland or sagebrush-grasslands, and notes it will use wet meadows and marshes at high elevations when the meadow vole is absent. Dry sagebrush-steppe and dry grassland reads montane. Wet sedge meadow and streamside reads meadow vole, unless the elevation is high enough that meadow vole is not present at all.

Size runs a real range across sources

Montana's Natural Heritage Program gives 5.5 to 7.5 inches nose to tail tip. Montana's Department of Agriculture gives 5.5 to 8.5 inches. The National Park Service's Yellowstone account gives 5 to 7.6 inches at 1.2 to 3.2 ounces, the only weight figure found from a state or federal source.

Color and build

Blackish brown to black on the back with a gray cast, pale buffy sides, a whitish belly and dusky feet, described as camouflage for dry grassland. Other accounts give brownish to grayish-brown, occasionally grizzled, with silvery-gray underparts and silver-gray feet. Stocky body, short legs, small eyes, and ears small enough to be hidden in the fur. The tail is short and bi-colored, running about one third the length of the vole's head and body.

Deer mouse: go by behavior

Against the deer mouse, go by behavior rather than by looks. Deer mice are strongly bi-colored, tannish-brown above with a white stomach, with large ears and eyes and a long bi-colored tail. The faster tell is that deer mice do not make ground surface runways or tunnel systems and leave little sign of their presence, and they commonly occupy homes and other structures. Voles do the opposite on both counts.

Long-tailed vole: the name does it

Against the long-tailed vole, the name does the work. A long-tailed vole's tail runs more than 50 percent of body length, against the montane vole's roughly one third of head and body, and long-tailed voles tend not to create surface trails at all.

Folk names, not identifications

Field mouse and meadow mouse are folk names, not identifications. Both get applied to several unrelated small rodents and tell you nothing about which animal is actually in the yard. Mountain vole is a genuine alternate name for this species and is used interchangeably by Montana's own agriculture department.

Signs of Infestation

Surface runways, and no mound

One to two inch wide trails worn through matted grass, connecting open burrow entrances one to two inches across, with vegetation clipped to ground level alongside well-traveled routes. Feces and small pieces of clipped vegetation accumulate in active runs. Colorado State Extension adds spongy soil underfoot from burrowing, and hawks circling and diving into a field, as two more reliable signs.

Girdled bark, capped at the snow line

Girdled bark at the base of trees and shrubs, capped at the snow line. Irregular patches of gnaw marks at various angles, about 1/8 inch wide, 3/8 inch long and 1/16 inch or more deep. Colorado State Extension gives the width slightly narrower at 1/16 to 1/8 inch and notes that gnawed stems may have a pointed tip. Damage height is set by however deep the snow got, because that is as high as the animal could reach working underneath it.

The pocket gopher test, from the vole side

A vole builds no mound at all. If there is no excavated soil, only shallow unraised runways and open holes, it is vole. A pocket gopher leaves a fan-shaped mound of fine dry soil with a plugged, off-center entrance and no obvious opening into the burrow, over tunnels 2.5 to 3.5 inches across sitting 4 to 18 inches down. The traps, baits and methods for the two animals are not interchangeable, so getting this right first is the cheapest step available.

Eskers are always gopher

Eskers are the Mountain West winter version of that same test, and they are always gopher. At snowmelt a pocket gopher that worked under the snowpack leaves long, curving, snake-like solid ropes of soil lying on the surface, because it packed its excavated dirt into tunnels in the overlying snow. Colorado State Extension notes the actual hole the soil came from sits near one end or the other of the rope, not underneath it. A lawn that comes out of the snow laced with grass trails is voles. A lawn that comes out with soil ropes lying on top of it is pocket gopher.

No runways does not mean no voles

Absence of runways does not prove absence of voles. Montane voles make surface runways through grass but may not use runways in other kinds of vegetation, so a shrubby or non-grassy planting can hold voles without showing the classic trail network.

No useful sound

No audible sign is documented as a practical way to identify vole activity. Do not wait to hear something.

No useful smell either

No distinctive odor is documented as a reliable identification cue. The runways, the holes and the bark damage are what you go on.

Prevention and When to Call a Pro

Cut the cover, and keep cutting

Keep cutting it. Published guidance agrees this is the single most effective step. Colorado State Extension calls elimination of weed ground cover and tall grasses by frequent close mowing, tilling or herbicide application the most successful and longest-lasting method available. Montana adds a useful timing cue: cut grass before the blades begin to bend over or curl toward the ground.

A bare-ground buffer, right width

Clear a bare-ground buffer, and use the right width for the job, because the published figures answer different questions. Around an individual tree or shrub, pull mulch, weeds and ground cover back two to three feet from the trunk. Between a yard and adjacent native vole habitat, a six to eight foot bare strip is suggested. Around an agricultural field, Montana recommends a weed-free zone ten feet or more wide, because voles avoid crossing that much open ground.

Guard trunks, sized to the snow

Guard young trunks with quarter-inch hardware cloth, sized to the snow rather than to the ground. Bury the cylinder six inches below grade and run it well above, at least the 14 inches Montana gives for exclusion or the 18 inches Colorado State gives for trunk guards, extending it up the trunk past the snow depth you normally get, because voles girdle at whatever height the snowpack lets them stand. Secure the top with mesh so crevice-dwelling birds cannot be trapped inside. Skip solid plastic and paper wrap-arounds, which trap moisture against the bark.

Montana's exclusion fence spec

It is the most complete one found and it is worth following exactly. Quarter-inch hardware cloth at least six inches below ground and at least 14 inches above, with the top two inches bent away from the protected area at a 90 degree angle, or a four-inch strip of flashing along the top, so a climbing vole gets no toe-hold. Set the fence posts on the protected side, since voles will climb the posts otherwise.

In hay country, treat the edges

In irrigated hay country, the reservoir is almost never the field. Treat the edges. Adjacent crop fields and irrigation systems are protected by mowing, spraying or grazing ditch banks, rights-of-way and waterways. UC IPM makes the same point from the treatment side, recommending that ditch bank and non-cropland work happen in fall or spring before reproduction peaks, to stop populations expanding into the crop rather than chasing them once they arrive.

Work in the fall, before snow

Work in the fall, before the snow. Anyone trying to avoid winter tree gnawing and turf damage should knock the population down the previous fall. For alfalfa specifically, grazing or mowing in late fall when active plant growth has stopped removes both habitat and food and stresses the winter population.

Tillage and flood irrigation

Both work mechanically. Tilling destroys runways, burrow systems, cover and food supply in one pass, which is why beds of annual plants suffer less than perennial plantings. Flood irrigation reduces vole numbers in fields, but control has to run along the field borders at the same time, because voles flee to those edges.

Plant against them where you can

Plant against them where the setting allows. Colorado State Extension suggests short grasses that do not mat or lodge, such as buffalo grass, blue grama or dwarf fescues, which give little protective cover, and crown vetch, a legume voles find unpalatable, along orchard and field boundaries.

Things that do not work

Listed so nobody wastes money on them. Frightening devices are ineffective. Fumigants are ineffective because vole burrows are too complex and porous for gas to reach the animals. Thiram and capsaicin repellents give only short-lived protection and voles habituate. Predator urines need impractical concentrations. And house cats should not be used: they kill native birds and amphibians indiscriminately, and free-ranging cats spread the parasite that causes toxoplasmosis through their feces.

Bait is an escalation step

Much of it is not a homeowner product. Zinc phosphide and chlorophacinone are restricted-use in agricultural settings and require a licensed applicator. Where general-use anticoagulant products are registered, most labels restrict above-ground outdoor use to tamper-resistant bait stations and limit placement to within about 100 feet of a residential or farm structure. Read the label before buying anything.

The property risks, named

The property risks here are real and worth naming. Girdling of 50 percent or more of a trunk's circumference will likely kill the tree or shrub. Utah State Extension puts production loss in alfalfa hay and grass pasture at 10 to 50 percent from vole activity. UC IPM breaks alfalfa damage into three parts: taproot and top-growth consumption causing reduced vigor or plant death, loss of irrigation water down burrow systems, and chewing on underground drip lines. Montana adds that burrowing can disrupt irrigation and undermine embankments and earthen dikes. A federal review cites a documented 36 percent production decrease in a large apple orchard over a two-year period of extremely high montane vole numbers.

On disease, both halves

On disease, the accurate answer is two-sided and both halves matter. Montana's Department of Agriculture and Utah State Extension independently agree that voles are capable of carrying plague, tularemia and hantavirus organisms, and that they rarely transmit disease to people because contact is infrequent and voles do not move into homes the way deer mice, house mice and pack rats do. Both are statements about the genus rather than findings specific to montane vole. There is one montane-vole-specific finding: in a multi-year small-mammal survey in Jackson Hole and Grand Teton National Park, with serology run by the Centers for Disease Control and Prevention, only three of the 18 rodent species screened tested hantavirus-seropositive, and montane vole was one of them alongside deer mouse and meadow vole. Positives clustered at five specific sites rather than being scattered. No published record links the vole-associated strain to a human case.

The plague reservoir is an open question

The plague reservoir question is open, and that is stated rather than filled in. The same Grand Teton program began plague work in 1995 specifically to test the long-standing hypothesis that voles serve as a reservoir between plague outbreaks among ground squirrels, collecting fleas for culture by the federal plague laboratory in Fort Collins. No published outcome for that test has surfaced. Treat plague as the genus-level capability the two extension and state sources support, not as a settled reservoir finding for this species.

Never handle a vole without gloves

Never handle a vole, alive or dead, without gloves. Both state and extension sources say so plainly. Bury dead voles rather than leaving them out, and Montana adds using a DEET-based repellent when handling rodents, to avoid attracting the fleas that may leave the animal and bite you.

Call at the agricultural threshold

Call a professional when the colony count crosses the agricultural threshold, which is a real number. Montana's Department of Agriculture says producers should consider control when colonies, identified by groups of one-inch holes, reach four to five per acre. The alternative trigger is trap catch rate: set several dozen traps, and if trapping success exceeds 10 percent, start control. Their worked example is 36 traps set in a field with four voles caught by the next day. The federal review puts the same idea in density terms, noting that once populations reach roughly 200 per hectare, substantial damage is generally inevitable.

Call when a crop is at risk

Call when the asset at risk is a crop or a planting rather than a lawn. Alfalfa, irrigated hay, orchard, nursery and vineyard damage escalates fast and is largely invisible until green-up, since root and crown damage in dormant alfalfa often does not show until spring. Restricted-use products alone put field-scale control in licensed hands.

Call before the bad winter

Call before the winter you expect to be bad, not after it. Both Montana and Utah State point at the previous fall as the control window. A call in April is a call after the damage is already done.

Call when the diagnosis is in doubt

Call when the diagnosis itself is in doubt. If the lawn shows soil mounds or snowmelt eskers rather than grass runways, the animal is a pocket gopher, and the traps, baits and methods for the two are not interchangeable.

Colorado is clear, Wyoming a gap

On legal status, Colorado is clear and Wyoming is a genuine gap. Colorado Parks and Wildlife names montane vole in its nongame wildlife list, which makes it protected by default, and then specifically allows voles to be captured or killed when creating a nuisance or causing property damage. Wyoming's nongame mammal list names meadow vole but not montane vole, and no published source establishes whether that is an omission, a pest-statute default, or something else, so verify with Game and Fish before trapping or relocating in Wyoming rather than assuming Colorado's treatment carries across. Montana ranks the species S5 with no agency status attached and runs a state vertebrate pest program that publishes vole control guidance with no permit or season language on the animal itself. Idaho lists it present and native at a state rank of S4. There is no federal listing anywhere in the range, no rabies vector designation, and no relocation ban.

Frequently Asked Questions

How do I tell vole damage from pocket gopher damage?

Look for a mound. A vole leaves none: just one to two inch wide runways worn through matted grass with open holes an inch or two across, clipped vegetation and scat in the runs, and spongy soil underfoot. A pocket gopher leaves a fan-shaped mound of fine dry soil with a plugged, off-center entrance and no visible hole, over tunnels 2.5 to 3.5 inches across sitting 4 to 18 inches down. After a mountain winter the gopher adds one more tell voles never produce: eskers, long snake-like ropes of soil lying on the lawn where it packed excavated dirt into tunnels in the snowpack. Grass trails at snowmelt mean voles. Soil ropes mean gopher.