Monday, February 5, 2018

Under the Snow

By Beth Sullivan
It has been an interesting winter so far. We have had some really terrifically, deep, cold spells - some when there was snow on the ground, another time when the ground was bare. It is the time of severe cold with no snow cover that is hardest on plants and animals. While snow can be a nuisance or a hazard or a chore for us, it is an important factor in survival during the winter for so many elements of wildlife.
After this most recent snow fall, 7 inches here, of lovely fluffy stuff, it was interesting to get out and look for tracks in the snow and evidence of life underneath . Small mammals will actually thrive under the snow pack. Voles and mice have stored seeds and grains in their burrows since the fall. While most mammals will slow down a bit during the winter, many will remain active, tunneling shallowly under leaves and loose soil. It is not uncommon to see shrews or voles disturbing the soil under birdfeeders, like small earthquakes as they search for seed remnants or insects. However, even such small movements are very noticeable to predators. But once the snow blankets the ground, they can actually tunnel more freely. They can move between protective hiding places and food sources and usually avoid detection.
My resident chipmunk emerged from her semi-hibernation, to pop her head through the leaves in perfect position under the bird feeder. I watched as she stuffed her cheeks full of seeds, several times, then retreated into the burrow. This was a day before the snow storm. I wonder how she knew. I have seen wonderful images of foxes triangulating their senses on an underground burrow, then leaping high and diving head first into the deep snow to catch their prey. I have witnessed it only once, and it is truly a wonder to watch. Owls have hearing abilities that allow them to do the same, and while they do not hurl themselves head first into the snow, they can land with spread wings and thrust their talons deeply to latch their target.
A Fox family made this den and the tracks and dirty snow indicated it was actively used.

A large bird of prey, likely an owl, was able to hear a small mammal under the snow cover. Photograph by Rick Newton.

When the snow melts, the  tunnels used by small mammals are revealed.

My resident chipmunk come out to snack in between storms.

Evidence appears come Spring

When the snow melts in the spring, it is also easy to see trails etched into the grasses and dirt that point out the well-worn paths these creatures have used all winter. It can be a problem when these trails wander through and under favored garden plants.
This is the time of season when brush piles and tangled hedgerows are their most valuable as refuge in the winter for many creatures. The heavy snow catches on upper branches and preserves open areas beneath for hiding. Dense shrubs that are alive provide an extra bonus. Small mammals will seek living bark and gnaw it for valuable sustenance. However, the longer the snow is on the ground, the longer they have to gnaw, and when spring arrives, stems have been girdled and the branch will die. Under the bark of trees, insects remain, some in a suspended state - some as larva, some as eggs - but available as food for birds if above the snow line, and for shrews under the snow.
The deeper snow cover also offers insulation. Hard to believe but the snow pack remains warmer, closer to the freezing point, while the air above may have temperatures plummeting to zero. Plants survive bitter winters much better when there is a constant snow cover.
Whether you observe from a window, or strap on snowshoes and get out into the snow, take some time to think about what is happening below the drifts. Think of all the wonderful adaptations wildlife has to survive in the places we preserve for them.
Twigs under the snow are gnawed by small mammals while protected by snow cover.

Don't you wish you could read the story these tracks tell.

Winter presents a bigger challenge for a fox who will need to locate food deep under snow. Photograph by Rick Newton.

Photographs by Beth Sullivan unless otherwise indicated.

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