A Blanket of Snow
Diary entry on January 20, 2019: “Woke up this morning to see over twelve inches of snow on the ground and still coming down. I knew the wind was picking up speed when I heard the shutters banging and saw the spruce trees bending. After breakfast, I began shoveling sidewalks and a path to the woodpile.”
Although most people consider a snow storm an inconvenience, in most cases a snow storm is not life threatening. However, deep snow can be devastating to some species of wildlife, especially if the snow remains covering the ground for an extended period of time.
The larger animals (predators) find deep snow a severe challenge. In winters with deep snow, deer will have a tendency to yard up (gather in groups) in stream bottoms, hemlock and other evergreen groves, where they find protection from the snow and wind. To feed, the deer make paths through the deep snow, which enables moving about much easier. Eventually, the food supply in the surrounding area will become depleted. When this occurs, winter mortality will be evident. Usually, the younger deer, which need more food to survive, will die first because they cannot reach as high as the older deer. In one study done, it was found that larger deer can maintain their weight on less food; however, younger deer need either the same amount of food or more to survive.
Predators, such as the foxes, weasels, fishers, coyotes, bobcats, hawks and owls, which stay active throughout the winter months will have a difficult time finding food due to their food supply being hidden by the snow. Voles and mice are vulnerable to predators when the ground is bare. After the ground freezes, their shallow burrows offer little protection from the elements; however, when the ground becomes covered with snow these animals are given some protection from the predators that hunt them both day and night.
These predators keep the vole population in check. If voles, mice and moles, are well fed, they have the ability to reproduce rapidly. A study was done on a well-fed vole, in captivity, which produced 17 litters in one year, averaging five young after a 21-day gestation period. In turn, these young can produce their own litters within one month. If you’re a mathematician, it will not be hard to figure out how many voles this could add up to in a year’s time. However, voles are food for many predators, such as foxes, weasels, fishers, coyotes, bobcats, hawks and owls.
During the winter months, these smaller animals will form communal nests that provide heat. It has been found that a huddled mass of ten voles keeps a nest between seven to twelve degrees warmer at ground temperature and 25 degrees warmer than the temperature above the snow. There are disadvantages of these communal nests, with the competition for food and the increased chance of predators finding nests.
Once the blanket of snow reaches six inches or more the little red squirrel will begin living its life beneath the snow and only occasionally venturing to the surface. The red squirrel will construct an extensive tunnel system under the snow and feed on caches of pine cones it had stored during the fall. As long as the surface ground remains cold the little red squirrel will stay underground.
Rabbits are light enough to walk on top of the snow, enabling them to reach food that is higher. Snowshoe hares, ermines, etc., are protected by the whiteness of the snow due to their fur changing to white during the winter months. Even hibernating animals, such as the woodchuck, benefit from heavy snow. While hibernating, woodchucks keep their body temperature above freezing. This is done by shivering when its body temperature drops; however, shivering, which produces heat, uses up body fat. A snow cover on the ground acts as an insulated blanket, which keeps the frost and cold from penetrating down to the woodchuck’s den.
As the snow deepens and the temperature drops into the single digits, the grouse will fly into a snow bank (snow cave) to spend the night. The snow bank will actually keep the grouse warm. This is because the earth stored up heat throughout the summer, and the snow, being a good insulator, keeps this heat from escaping into the air. The ground would freeze solid if we had no snow. With at least seven inches of snow accumulated on the ground, the temperature at the soil surface rises to 32 degrees and remains constant unless an extreme change in air temperature occurs. It has been recorded that, ground covered with two feet of snow was 50 degrees warmer than the air immediately above the snow pack.
So, when talking about a blanket of snow, we really mean a blanket.