Runways & Burrows
A good indicator that you have voles in your yard is the visible, above ground runways that connect their burrow openings. These well-defined, surface runways, about two inches wide, are typically constructed in grassy areas.
Vole runways are formed by a combination of voles eating the grass blades and the steady traffic from their shallow underground burrow to seek food along the runways. Runways are often hidden by ground cover, so you may have to pull back overhanging cover to find them.
The opening to a vole burrow can be identified by neat, round holes that measure an inch or two in diameter. Vole holes can be found in open turf or hidden under ground cover, plantings or mulch.
Plants & Trees
Another tell-tale sign of a vole infestation are plants that have wilted or appear yellowish. If a light tug on a plant lifts it easily from the soil, chances are good that its roots have been devoured by a vole.
When green vegetation is scarce, voles will gnaw on the bark of fruit trees or shrubs. Vole damage to tree trunks is normally found a couple of inches above ground to a few inches below ground. When a vole gnaws completely around the trunk or roots, it can cause the tree or shrub to die. Signs of tree damage by voles are a delay in fruit production and uncharacteristic leaf color.