Voles, Ugh!

by Andrea Laine, EMGV

I should have known I’d have voles in my garden this Spring. Afterall, I had a mole last fall. It left behind underground tunnels. When I began to dig around in my perennial beds in March I could feel the spongy soil at the surface along the tunnel lines. A warning sign was right there in front of my eyes! But I was preoccupied with doing all the garden chores that come with spring including enthusiastically adding new plants.

A brief summary on moles vs. voles. Moles are meat eaters. They swim through the soil a foot or more below the surface and consume insects, grubs, worms, and spiders in their path. This action can disturb the root systems of plants in their way which may harm the plants, but won’t necessarily destroy the plants. Voles are vegetarians. Two species of  vole are found in central NC. I probably have pine voles  (Microtus pinetorum) which use the tunnels left vacant by a mole to reach bulbs, tubers and roots of plants, trees and shrubs to eat. Voles will also eat stems and fruits. The herbaceous plants they pick have little chance of survival. Moles work alone; voles work in groups of several adults and young.

As I continued with my spring gardening, I began to take notice of once healthy perennials and annuals suddenly showing signs of decline. Thinking it might be too hot and dry too soon in the season, I watered more, placed a shade tent over a new Sedum ‘Autumn Joy’, and hoped for the best as I turned my attention toward the myriad other tasks on my garden’s “to do” list. A short time later the plants I had on my ‘watch’ list began to flop over and reveal … the dreaded vole hole.

Strategies

Had I resumed gardening with more awareness this spring, I may have taken some strategic actions to deter voles from staying in my garden. Voles feed all year. Damage to woody plants is greatest in winter. So, better late than never – I acted in June and will keep my defenses up.  

Here are some actions to consider, beginning with those deemed most effective by Extension resources:

  • Trap voles with mousetraps baited with apple slices or peanut butter. Be aware that a depredation permit is required to trap voles and you may attract and kill shrews with traps. So before expressing glee at a capture, understand how to identify between the two. Shrews have pointier snouts and shorter tails than voles. Trapping is the only way to positively identify the animal that is doing the damage. I have assumed that I have pine voles because meadow voles typically live in grassy habitats at ground level, however, meadow voles sometimes burrow underground, too.  (Distinguishing features of each are noted in the first link under Further Reading.)  When handling dead rodents and traps, wear disposable gloves and wash hands well afterward. Bury the dead rodents immediately.
  • Invite predators. Voles live a few inches underground which provides protection from their wild predators: Snakes, owls, hawks, crows, weasels, foxes and coyotes. Building a lookout perch can help crows, hawks and owls scan the landscape for voles. I have noticed more crows than usual in my yard this year; in the future this could be a warning sign for me. Of note, a pet cat is one of the best predators of voles.
  • Reduce their habitat. Laying three inches of mulch in your landscaped beds is great for shutting out weeds and helping the soil stay cool and moist, but it also provides great cover for voles. Woody groundcovers like juniper and fabric weed barriers act similarly. Use one-inch of mulch and commit to stay on top of weeding chores (easier said than done). Also, in the fall, rake fallen leaves away from the base of trees and shrubs.
  • Protect trunks of younger trees and shrubs with wire mesh. (Guards made of other materials are not as effective.) Embed cylindrical wire guards up to three inches into the soil at the tree base. Guards should be taller than average snow level. These are easier to install at planting time, and damage to tree roots is also less likely if these are installed at planting.
  • Get sharp. Surround new plantings with coarse gravel. And, place small piles of pea gravel around the base of fruit trees to prevent chewing by voles. This is another action that falls under habitat renovation. It dissuades voles from sticking around because scurrying around among hard material with pointy ends is uncomfortable.
  • Water in a repellent.  Much like commercial sprays formulated to deter deer, rabbit or squirrels from munching on plant foliage, similar products coat the roots of plants in distasteful substances. To reach the roots, you sprinkle grains of repellent on the soil surface then water well. The repellent is made from natural ingredients.   
  • There are chemical solutions termed rodenticides; they require a license to use.

It’s hard to believe that a few small rodents can do much damage to a garden, especially to established trees and shrubs. Voles are a mighty force of nature. They can kill trees by eating the bark at ground level. This is called girdling and it removes the tree’s phloem thus preventing the leaves from transporting food to the roots. Over time, the tree will die.  

Ah, but hope springs eternal. While watering in a round of vole repellent one day, I noticed a small sprig of sedum making its way through the soil surface. Evidently, some fragment of root escaped being munched by the voles and is yearning to live.

Sources & Further Reading

Reducing vole damage. This link includes illustrations useful in identifying mouselike rodents.  https://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/woodland-steward/FS654_ReducingVoleDamage.pdf

https://content.ces.ncsu.edu/voles-in-commercial-orchard-and-ornamental-nurseries

https://extension.umd.edu/hgic/topics/voles

NC pesticide law and regulations:  http://www.ncagr.gov/SPCAP/pesticides/Authorit.htm https://www.epa.gov/rodenticides

About depredation permits: https://www.ncwildlife.org/Licensing/Other-Licenses-Permits/Depredation-Permit

All photos by A. Laine

Moles, Voles, Tunnels and Holes

20161203_142433
Photo – Ann Barnes

“Mom, there’s a hole in the garden!” are not words any gardener wants to hear, especially when the hole happens to be perilously close to a prized plant. When my son alerted me to the one pictured above, I had to do a little research to determine whether the resident of the hole needed to be evicted. It can be tricky to identify the critter by the hole, so I started by researching the “usual suspects”. Two of the most common tunneling pests in our area are moles and voles. Although their rhyming names can cause confusion, only one of these makes a meal of your plants.
Moles: If you have raised tunnels in your yard, moles are probably to blame. Moles are 4 – 6 inches in length, have small eyes and concealed ears, and paddle-like front feet designed for digging. They tend to be solitary creatures, and 3-5 moles per acre is considered to be a high population. While hunting areas are close to the surface, a mole’s den is located deeper underground. Entrances to dens may have mounds of soil – molehills – around them. Moles don’t eat plants, but their tunnels can cause damage by disturbing the root systems of plants growing above them. These tunnels are where moles hunt for the grubs, earthworms, and other invertebrates that make up their diet. Some of the grubs and insects in moles’ diets are lawn and garden pests. Mole tunneling also helps to aerate the soil, which can improve drainage and move mineral nutrients and organic matter around. Still, the tunnels’ damage to the landscape causes many homeowners frustration.
North Carolina is home to more than one species of mole. The Eastern mole (Scalopus aquaticus) is the most common. The star-nosed mole (Condylura cristata parva) is less common in our area, but is a protected species. This limits control options for all moles. Moles can be trapped, but a permit is required. There are no pesticides approved to kill moles in NC. Commercial repellents are available but need to be reapplied frequently. “Home remedies” such as gum or glass shards have not been shown to be effective. If tunnels are not extensive, simply pressing soil back down will lessen the nuisance factor.
Voles: Voles are small rodents that resemble mice. Pine voles (Microtus pinetorum) and meadow voles (Microtus pennsylvanicus) are two of the vole species found in our area. Meadow voles live mostly above ground, make runways through grassy areas, and gnaw on plants at ground level. Pine voles dig a series of underground tunnels less than a foot deep, and sometimes also use mole tunnels. One to two inch diameter entrance holes may be found in garden beds. Pine voles eat bulbs, tubers, and roots of plants, and can cause a lot of damage to ornamental plants. They may also feed above ground at night. Several adults and young can live within a tunnel system, and adults can have as many as 5 litters in a year.
Voles prefer to have some protection from predators. To make your yard less attractive to voles, keep grassy and weedy areas mowed, and do not mulch deeply. Trapping is most effective in fall and winter, when their food supply is less abundant. A trap baited with apples and peanut butter, placed under a bucket next to a vole hole, is recommended. Baits can be used to poison voles, but must be used carefully. Valued plants can be protected by using a barrier (such as hardware cloth) or planting in pots, but this may not be feasible for large shrubs and trees.
After spending some time watching the hole in our garden my family determined that neither moles nor voles were responsible.

DSC_0041
Photo: Ann Barnes

Chipmunks: I had expected to find a vole using the hole in the garden, but it was home to a chipmunk. Chipmunks (Tamias striatus) are a type of ground squirrel that live in wooded areas and around homes where food is plentiful. Like moles and voles, chipmunks live in underground tunnels. Chipmunks are omnivores, eating a variety of foods including seeds, nuts, berries, and insects. Some food is stored for winter in their burrows. Although they are not usually a major nuisance in the landscape, chipmunks can feed on flower bulbs and seeds for vegetable gardens. They also can burrow under foundations, patios and sidewalks, which may cause structural damage. Hardware cloth or other barriers can be used to keep chipmunks from tunneling under sidewalks or entering buildings. Reducing cover for chipmunks and keeping bird feeders away from structures will make your house less attractive to them. Repellents can be used but must be reapplied frequently. Chipmunks can also be trapped if they are causing damage to property.
These are not the only animals that could be digging in your yard. An environmentally friendly approach to a “mystery hole” would be to observe the area to find the hole’s owner, then assess whether the animal is likely to cause enough damage to require treatment. In our case, the family enjoys watching the chipmunk and have decided to leave it alone.
http://extension.psu.edu/natural-resources/wildlife/wildlife-nuisance-and-damage/small-mammals
http://www.extension.umn.edu/garden/yard-garden/wildlife/whats-digging-holes/
http://icwdm.org/handbook/mammals/Moles.asp
https://catawba.ces.ncsu.edu/2015/05/355938/
https://wayne.ces.ncsu.edu/2015/12/moles-or-voles/

-by Ann Barnes

 

Two Classes – May 5, 2013

Two Extension Gardener Seminars are being held tomorrow, May 5.

Worms in My Garden – Sarah P. Duke Gardens, 2-4pm

Join a Durham Extension Master Gardener at the Burpee Learning Center in the Charlotte Brody Discovery Garden to learn all about the benefits of Vermicomposting and how easy it is to compost your trash. To register call 919-668-1707 or email slsmith@duke.edu

Outsmarting the Garden Critters, North Regional Library, 3-4pm

Join a Durham Extension Master Gardener to learn how to garden despite the deer, groundhogs, voles, and more. Call 919-560-0231 to register.