Vole trails and winter lawn damage

This guide is part of our Montana Winter Property Guide. It relies mainly on Montana State University Extension, including a publication by retired MSU Extension wildlife specialist James E. Knight, with other extension programs named where we use them.

What are those winding trails in my lawn after the snow melts?

Almost always vole runways. MSU's Knight describes the spring surprise this way: snowmelt reveals little trails scattered along grassy areas, because voles have been at work all winter under the snow, removing green vegetation down to the soil and creating a maze of runways and bare patches. Turf is damaged when well-traveled runways and adjacent areas are clipped close to the ground.

University of Minnesota Extension describes them as a series of criss-crossing trails usually seen in early spring just after snowmelt, and notes voles may leave larger patches of dried grass that served as storage areas and nesting material. Feces and small pieces of vegetation are usually visible in the runways, according to MSU, which is a handy confirmation when you are standing over one.

What is a vole, and how is it different from a mole?

Voles are small rodents. University of Minnesota Extension describes them as small brown rodents about the size and shape of a mouse, with small ears and a short tail. Utah State University Extension puts them at 3 to 6 inches long. Their burrows have several entrances, and Minnesota mentions small holes about 1 inch across.

University of Illinois Extension notes the confusion directly: vole damage is frequently mistaken for mole damage, but moles are not active during winter and actually tunnel below the soil surface. Surface runways are the vole signature. Minnesota adds that voles sometimes use mole tunnels, so moles get blamed for root damage they did not do. Snow mold looks different again, appearing as a webby or matted patch rather than a trail, as our guide on what happens to a lawn under snow describes.

Why are voles so active under the snow?

Snow gives them a protected roof. MSU says voles are active day and night throughout the year and do not hibernate. They travel very well under snow if they can move freely through vegetation or loose material between the soil and the snow. University of Illinois Extension adds that they are protected from predators while feeding on grass blades and roots.

MSU's ornamental pest guide says voles move from surrounding uncultivated areas into landscaped yards and gardens during winter, and sometimes during drought, seeking food. Knight notes damage in gardens and lawns is generally next to natural areas where long-term vole habitat exists. That describes a lot of properties here, where a mowed lawn runs into a pasture, a ditch bank or native grass.

Why are some years so much worse?

Vole numbers swing naturally. Knight describes large population fluctuations characteristic every two to five years. Research he cites shows populations ranging from about two to more than 50 per acre in normal grasslands, and often over 100 per acre in alfalfa. Females may have one to five litters a year, with three to six young being typical, and a gestation period of 21 days.

Snow also plays a part. University of Wisconsin-Madison Extension points out that without snow cover, these animals are more exposed to predators such as hawks and owls, while snow cover offers protection. So a long, snowy winter over a good vole year tends to give you the worst trails. A low-snow winter brings different problems, but this is not usually one of them.

Will my lawn recover from vole damage?

Usually. University of Minnesota Extension says lawn damage is most visible in spring but rarely permanent, and that as the surrounding grass grows, it will cover up the trails. University of Illinois Extension says lawns usually fill in as conditions warm, though severe damage may require some overseeding.

The fix is simple. Rake out the dead grass and debris, then reseed bare stretches, as Minnesota recommends. MSU notes that excessive urine and feces can sometimes make re-establishing grass a challenge in the most heavily used runways. Our guides on when to aerate and overseed and our aeration and overseeding service cover what to do if a large area needs it.

Can voles kill trees and shrubs?

Yes, and this is the damage that matters. MSU says vole damage to trees and shrubs primarily takes place in fall and winter, and voles may girdle trees and seedlings and damage roots. Bark damage is usually on the lower eight to ten inches of the trunk, where it is protected by snow. Tiny marks from vole incisors can be seen on the bark, which helps separate it from other causes of bark loss. MSU's guide shows bark stripped from juniper as an example.

A girdled trunk has lost its bark all the way around, so check young trees as soon as the snow leaves the base. If you find chewing, have a closer look. A complete ring can kill a young tree, and a professional can tell you whether it is worth keeping. Justin Johnson, our ISA Certified Arborist (RM-8889A), handles tree health and risk assessments across Missoula and the Bitterroot Valley. Our guide on deer browse in winter covers the damage higher up the same trunk.

How do you protect young trees from voles?

Hardware cloth cylinders are the standard, and MSU calls exclusion often the best method to protect seedlings and young trees. Use mesh of 1/4 inch or smaller. MSU's guide says to install hardware cloth at least six inches below the ground and extending at least 14 inches above ground, and Knight adds that it must be buried about 6 inches to keep voles from burrowing under it. Be sure the cylinders extend above the expected snow level.

University of Minnesota Extension suggests positioning the cylinder about 6 inches from the trunk and leaving no gaps at the bottom. Install in fall if you can, since digging in a buried cylinder gets harder once the ground freezes. MSU also lists trunk guards and poly wrap for young trees, and commercial plastic cylinders can work well when used properly.

How do you make a yard less attractive to voles?

Take away the cover. MSU says to eliminate weeds, grass, litter and loose mulch that provide cover and food, and notes that mowing grass short around trees reduces the ease of vole travel. University of Minnesota Extension adds removing woodpiles and debris, keeping grass trimmed short and cleaning up bird feeders, which attract voles.

The boundary is where this pays off. Knight's advice for properties next to native grass is to cut as short as possible in a 10-foot swath next to those areas, which makes it hard for voles to move into your yard under the snow. Keep the last mowing of the year short as well: University of Illinois Extension recommends continuing to mow until the grass is completely dormant, with a final height of about two inches. A good fall yard cleanup takes care of a lot of this at once, and we offer recurring lawn care through the growing season.

Knight adds one trick for winter: voles are reluctant to go over the top of packed snow they cannot burrow through, so packing snow along an edge can obstruct their movement between native grass and lawn. Some people do this with skis or a snowmobile. Just keep traffic off septic drainfields, for the reasons in our guide to winter checks for empty and vacation homes.

Do repellents, traps or scare devices work on voles?

With limits. MSU says capsaicin is registered for voles in Montana and can be sprayed on non-crop plants such as ornamental trees and shrubs, but Knight notes repellents give only short-term protection and must be reapplied so often that it is usually not practical. Frightening devices do not work: lights, sounds and ultrasonic devices have been tested and none proved effective in controlled experiments, he says.

Trapping suits small populations. MSU's guide says unbaited mouse snap traps can be placed perpendicular to the paths with the trigger in the trail, on areas of a few acres or less. Baited traps should be covered overhead to prevent injury to non-target animals. Keep pets and children in mind. University of Minnesota Extension says most vole pesticides are restricted to certified applicators, and any bait should be in a bait station and used according to its label. Knight notes voles are nongame mammals that can be controlled when causing damage, but he advises contacting your state wildlife agency about local rules.

Do cats or predators solve the problem?

Not by themselves. Knight says many predators eat voles, from coyotes and snakes to hawks, owls and weasels, but because of the voles' high reproductive rate, populations are unlikely to be controlled by predators. Cats will kill some, but not enough for control, and they kill other species that are beneficial to a garden.

Who can help with vole damage?

Rodent control is not on our service list, but we can handle most of the work that follows voles. That includes spring raking and cleanup through our seasonal clean-ups, lawn repair, reseeding and tree work. Over the winter itself, our snow and 24-hour storm services keep drives and walks clear. Call (406) 215-7319 or request a free estimate.

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