It's spring, almost summer, so you know what that means for our lawns - above-ground tunnels wind around the surface like toy-train tracks. We curse the little tunnelers that create these visual impediments, but this year the usual handiwork is nowhere to be seen; at least my lawn is clear. Why in some years do we find long, snakelike mazes, while other years our lawns are trackless? And who are these critters that make these passageways in our grass?
Eric Larusson, an arborist at the Villager Nursery in Truckee as well as a plant and animal expert, lent his expertise in sharing some elementary facts. First, three common mammals invade our lawns and scurry in meadows: voles, moles, and gophers. Voles construct subterranean tunnels (and also take advantage of already-made tunnels crafted by gophers, ground squirrels, and moles) and in winter live underground. In summer, much of their activity occurs above ground in meadow "runways" they cut through vegetation close to the surface. Most of all, Larusson says, they love the condominium-like dwellings created in man-made rock walls.
Voles, who are also known as meadow mice, look like small hamsters, with compact, heavy bodies, short legs, small eyes, and partially hidden ears. They eat fruits, seeds, fungi, bark, and sometimes leaves. Some of the most common voles in our area are mountain voles (Microtus montanus), long-tailed voles (Microtus longicaudus), and sagebrush voles (Lemmiscus curtatus). According to Larusson, the role of a vole in the ecosystem is to convert plant material into food for our forests' carnivores. Predators such as owls, hawks, ravens, eagles, snakes, bobcats, mountain lions, and coyotes love to munch on the nutritious, and abundant, voles.
Just how prolific is the vole? According to the UC Agriculture and Natural Resources website, females mature in 35 to 40 days and have five to 10 litters per year. However, because of their sheer numbers, voles seldom live longer than 12 months since they provide ample bait for predators. The "Sierra Nevada Natural History" guide confirms the animal’s fecundity: "Voles can breed within three weeks of birth, giving them about the highest reproductive potential of any mammal."
In the Sierra, voles thrive in the subnivean (the world under the snow) environment. Larusson once wrote in a column: "The longer the snow cover, the more they eat. We always say that when ice skating is good, voles suffer." Aha! The reason vole traffic is less or nonexistent this year!