Below is an excerpt of a Plug article sent out this Fall from North Creek Nurseries.
Our most common vole in Pennsylvania is the native meadow vole, Microtus pennsylvanicus.
Winter time is prime time for small rodent damage. Under snow cover, these native mammals run through their long tunnels in search of food. What's on the menu? It's the roots of your favorite grasses and the soft inner bark of trees.
While all of these small mammals can cause damage in the garden, the vole's tell-tale sign is the visible raised-earth of their tunnels and the small openings where they dart out to access food. (Learn more about the differences of these small mammals and more about the vole here)
Our most common vole in Pennsylvania is the native meadow vole, Microtus pennsylvanicus.
According to the Penn State Extension, "The meadow vole is most often found in extensive grassy or weedy areas such as old fields and moist hillsides with heavy ground cover. However, stream and pond banks, orchards, pastures, hay fields, and fence rows also provide suitable habitat for meadow and woodland voles. Meadow voles occasionally invade lawns, gardens, and nurseries. Woodland voles are most abundant in southeastern Pennsylvania, where they are common in old fields, thickets, gardens, orchards, and the edges of agricultural land, particularly where the soil is loose and sandy.
Voles eat a wide variety of plants, most frequently grasses and forbs. In late summer and fall, they store seeds, tubers, bulbs, and rhizomes. They eat bark at times, primarily in fall and winter, and will also eat grain crops, especially when their populations are high. Occasional food items include snails, insects, and animal remains. Voles are active day and night, year-round, with peak activity occurring at dawn and dusk. They do not hibernate. Their home range is usually ¼ acre or less, but this range varies with season, population density, habitat, and food supply."
Come spring, you could wonder why plants in the garden are not performing. When you tug on the plant, they pop right out of the soil.
During the lean winter months, voles chew up the roots of plants they find delicious. As the meadow vole is a native species, the plants that they co-evolved with and rely on for winter sustenance most heavily is our native plant species.
One of the things about gardening with native plants, and encouraging their use in the landscape, is that the literature about how to deter or get rid of this "garden pest" are all opposing ideas to the ways you might wish to garden.
Deterring small mammals from the garden includes such ideas as "habitat modification" and the encouragement to not leave leaf litter over winter, don't plant their preferred food sources, or don't leave standing plants in the winter because that is habitat for these creatures. These habitat modifications reduce habitat for all of our native insects and animals.
Vole repellents don't necessarily work, baiting utilizes toxic chemicals to kill voles and can affect other creatures in the garden, fumigants in the soil is the nuclear option, and trapping them - especially if there is a vole population explosion - appears to be a never-ending process.
So, even though voles are a garden pest in high numbers, it's a sign that your garden is reconnecting with the greater ecology of the landscape. Native grasses are habitat for native insect and other animal species, that includes voles, moles, shrews, and rabbits. These small animals depend on your native plants and in turn, support larger animals like hawks, owls, snakes, weasels, raccoons, foxes, badgers, and opossums.
So, while there is not a clear solution to this problem - Mother Nature will likely have it handled.