Voles are small rodents that resemble mice with smaller, stout bodies, hairy tails and a rounded nose. They actually fall into the same sub-family as muskrats and lemmings because of the angular shape of their molars. There are close to 160 species of voles worldwide, and voles are widespread on all continents except Antarctica. This does not mean that they are not well-adapted to cold weather.
Here in Colorado, voles spend the winter scurrying under the snow between hollow logs and burrows that offer additional shelter beyond the insulation provided by the snow. In the spring the melting snow will reveal a tangle of well-worn pathways that voles traveled during the winter under the blanket of snow.
Never Far From Home
Various species of voles thrive in almost all habitats. Meadow voles forage for seed in meadows and hay fields. Water voles dive and dart through streams, collecting luscious green plant shoots in spring and subsisting on bark, roots, and seeds in winter. The montane vole lives in high alpine meadows and feasts on the hardy plants of the alpine tundra. Their wide distribution and prevalence in a variety of habitats make them ideal food sources for predators in all of Colorado’s ecosystems.
A Yummy Snack
If you were a small predator, voles would be like Mary Poppins’ bottomless handbag full of high protein, energy-rich snacks. Even in winter, your sensitive ears reveal the scurrying and scratching sounds of voles beneath the snow. Humans may be intrigued to watch foxes and coyotes listening intently to the snowpack and suddenly pouncing to pull out a furry mouthful. No matter how many of these little critters are munched, there always seem to be more to be found.
Voles are a reliable, quickly replenishing food source for small and medium-sized predators in Colorado. Carnivores including martens, hawks, owls, coyotes and bobcats rely on voles as an important year-round food source. But, if all these predators are on the prowl for voles, how are there any voles left to be found?
Voles are what scientists refer to as R-strategists. R-strategists are creatures whose reproductive strategy is to produce many offspring quickly and invest little energy in rearing those offspring. Such animals typically have short gestation periods and have offspring who reach maturity quickly. This allows for rapid, exponential population growth and is the basis for the term “breeding like rabbits.” By contrast, many larger mammals like humans and elephants are considered K-strategists. These species produce few offspring and invest enormous amounts of time and energy in protecting and rearing them.
Busy Mama Voles
Female voles can produce up to 10 litters of ten offspring per year mostly between the months of March and October. Those offspring reach sexual maturity in about a month’s time. Since a vole’s gestation period is only three weeks, that original mother vole could produce another litter of 10 offspring a week before her first litter reaches maturity. This means that in four months, assuming all offspring survive, one mother vole with the help of her breeding daughters, granddaughters, and great-granddaughters could establish a population of 2,160 voles.
Of course, mortality from predation and other causes comes into play so fewer than that would actually survive in a natural ecosystem. But, thanks to their rapid reproduction rates and wide distribution, voles still provide an extremely reliable source of energy-rich meals for the hungry predators of Colorado.
Pete Wadden is the field science educator at Walking Mountains Science Center. When not writing about the culinary preferences of Colorado predators, he enjoys fishing and foraging for food of his own.
Humans may be intrigued to watch foxes and coyotes listening intently to the snowpack and suddenly pouncing to pull out a furry mouthful.