Voles are among the most abundant mammals in North America, but most people have never actually seen one. There’s a native vole species found pretty much anywhere from the Arctic into Mexico. There are a couple dozen species in North America, and about twice as many in the Old World.
These fuzzy beasts are one species I study (this Meadow Vole, Microtus pennsylvanicus, was at a rest stop in Massachusetts), and I wholeheartedly agree with the sentiment expressed in by the author of a recent review of vole genetics:
“Nobody has posters of voles on their wall,” said J. Andrew DeWoody, associate professor of genetics in the Department of Forestry and Natural Resources, whose study appears this month in the journal Genetica. “But when it comes down to it, voles deserve more attention.”
The paper discusses the often bizarre genetic and chromosomal diversity of voles. For most animals, differences in chromosome number is enough to make a new species, if not a new genus. Variability in chromosome number is apparently quite common in voles, sometimes within a single species.
Other researchers are interested in voles because of their range of behavioral systems. Some voles are monogamous, others are polygamous, while others vary their mating system depending on climate. Understanding the genetic differences and hormonal responses associated with that variation gives insight into sexual behavior in humans and other species.
My interest in voles has nothing to do with chromosomes or hormones. The abundance of voles makes them excellent test subjects for attempts to model species distributions. Where they occur is well known, and many of the environmental factors that limit their range is understood as well. There’s even a good literature on interactions between different species of voles.
Poke around in a field near you and you might find the runways that they build, a system of cleared trails that they run through, feeding on grass and other leafs. Follow a runway back and you may find the den where pups are born.
A vole is basically a breeding machine. A female becomes reproductive at a few weeks old, and can produce a litter of 3–4 pups every few weeks from then on. If not for intense predation, voles would easily take over the world.
Luckily for us, voles remain hidden, kept in bay by foxes, hawks, snakes, weasels, and a host more easily seen animals.