Northland Nature: Voles use the snow for protection from predators
A snowfall of several inches during December can be quite hard on many of the local wild critters. Besides the obvious cold cover, the snow hides food from them and the daily search for a meal can become difficult. With the coming cold, it is lik...
A snowfall of several inches during December can be quite hard on many of the local wild critters. Besides the obvious cold cover, the snow hides food from them and the daily search for a meal can become difficult. With the coming cold, it is likely that present accumulating snow will remain throughout the coming months.
But as often happens in nature, the same snow cover that spells disaster for many animals will also spell relief for others. With snow 6 inches to a foot deep, the cottontail rabbits and snowshoe hares find hiding places much easier to come by. While the former stays brown, the latter uses its white fur as an ideal camouflage in such a setting.
Though cold, the snowpack serves as a blanket for others to go under. Ruffed grouse will make use of such a site and bury themselves for several days if needed. Red squirrels will descend from the trees and tunnel for long distances under the snow. However, no one seems to make use of the snow for tunneling as do the voles.
Voles, often called meadow or field mice, are very common in the Northland. Unlike their longer-tailed cousins, the deer or white-footed mice, voles remain outside for the duration of the winter. If the winter provides its usual amount of snow, they do quite well out here. With a dark body and a short tail, these 5-inch rodents are quite easy to see as they scurry across the snow surface. Any voles caught out in the open during these chilly days may easily become a meal for many local predators. Hawks, owls, shrikes, foxes, weasels, skunks, raccoons, as well as the tiny shrews would not avoid such a meal.
In the warmer weather, there are even more predators in search of voles. With so many critters trying to eat them, the voles protect themselves with prolific reproduction rates, and they are able to have litters many times during the year. By December, the local vole population is quite high.
As the snow settles around them, they take advantage of it and form a network of tunnels. Digging and pushing themselves through the snow, they form burrows that may be hundreds of feet long. With turns and intersections, these subnivean mazes would challenge anyone to make their way around. Here they find protection from their many potential predators. And here they find an abundance of food. Much of the cold season is spent wandering through this sanctuary gathering seeds from the meadow and field plants.
Predators can and will invade their domain, but for the most part, the voles do well here. More snow gives them even more protection.
With many of these little critters running around under the snow, they create their own problem. All this activity creates a build up of carbon dioxide in subsurface snow. To combat this, the voles produce a number of openings at the surface. Here they climb up regularly for a look around the landscape and a breath of fresh air. Passing this snowy scene, it is not unusual for us to see these vole holes that are about the size of our finger. No tracks go out from them.
As we proceed through the winter and the deeper snows, we'll see these ventilation shafts less, but for now they are a regular sight in the snowpack of early winter.
Larry Weber is author of the "Backyard Almanac" and "Butterflies of the Northwoods." He lives in Carlton County and teaches natural science at Duluth's Marshall School.