Meadow voles, also known as field mice, are common pests in lawns and gardens and can be identified by the very clean very round open holes that they dig, as well as by above ground trails or runways that they use repeatedly. They are strictly an outside pest, as they do not invade homes or other structures the way house mice do. Their populations are cyclical in nature and typically three or four years may pass where their populations remain low and they are only an occasional pest problem, but about every 3-5 years their populations will experience explosive growth and they can become a significant pest in lawns and gardens. In my mole and gopher control service business that I operate in the San Francisco Bay Area, we've seen more voles in 2008 than in the prior sixteen years combined.
Voles typically secondarily invade pre-existing tunnels made by moles and gophers rather than dig their own(clearly having worked out that a lot less effort is required). Voles nest underground in the tunnels, but also run around on the surface following well worn trails between holes or from lawns into areas of heavy vegetation cover. In addition to causing significant damage to lawns, they can also damage a wide variety of plants that are used for ground covers, and they also eat bark and can girdle and kill landscape shrubs and even small trees.
Voles are easy to catch with the trapping techniques shown here, though be forewarned that in peak population years, there may be a lot of them to trap.
The first step in trapping voles is to identify the most active holes and runways. Active holes can be identified by looking for freshly cropped grass blades or other vegetation around the perimeter of the holes. The presence of spider webs or leaves or other debris in a hole indicates that the hole has not seen recent use and is not a good choice to set traps on.
The basic above ground set for voles is shown in the picture to the right. Two standard mouse traps are set with triggers facing the hole and the set is covered with a rectangular shaped cover which prevents the set from being disturbed, but more importantly it forces the voles to travel right over the trigger pan of the trap as they exit their holes. Note that for the purpose of illustrating the set, the cover in the picture to the right has been removed--when the traps are set, the cover would be staked down over the traps. The traps are firmly staked down to the ground with 20d nails inserted through holes drilled into the wooden base of the trap. Without these nail stakes, traps will move when they're sprung, and effectiveness of the set will be greatly reduced. I recommend using no bait whatsoever on the traps, as the cover forces the voles right onto the trigger, and bait will only encourage dogs, raccoons, skunks, and other scavengers to disturb the set.
In cases where the voles do not make holes you can trap them with a similar setup placing traps in their above ground runways. The setup is exactly the same except the two traps are set back to back in line with the runway, with the triggers facing outwards towards the openings of the plastic cover. Again, no bait should be used, as the voles will naturally seek shelter under the cover.
In situations where it may be desirable to use an underground inside the tunnel set for voles, such as where dogs or children are present, or at public schools or parks, and underground set using the Trapline Mole Trap is a very effective choice. A tunnel set using our mole traps is also a good choice where both moles and voles are present in an area, because the same set-up will be effective against both animals. The picture to the right shows a combination of moles, voles, and juvenile pocket gophers all taken from the same tunnel systems with the Trapline Mole trap. See the section on Moles for more information on how to set and place these traps.