Wildlife: Surviving the unseen world beneath the snow
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Over the holidays, about a foot of snow fell on the ridge. Each morning as I walked around the yard and into the woods, evidence of wildlife activity was everywhere. Deer trails, diggings by turkeys and skunks, and meandering tracks left by squirrels and mice were hard to miss.
The habitat beneath the snow, sometimes called "subnivia," was no doubt just as busy, though it is an unseen world that can only be inferred by careful observation.
Beneath the snow, a surprising diversity of scavenging insects, mites and spiders forage on decaying organic matter and dormant insects. Seeds, bark and other plant material sustain voles and deer mice. Shrews and weasels sit atop the subnivian food chain.
Snow insulates the world beneath it, creating a surprisingly stable environment. Temperatures stay within a degree or two of freezing, and perhaps more importantly, snow cover eliminates the chilling effects of the wind.
Blowing snow flows around boulders, trees and even the foundations of houses like water in slow motion, forming drifts. The snow deforms under the force of gravity and its own weight. Consequently, snow does not completely fill all the space it covers. Cavities form along logs, rocks, tree trunks and dense vegetation. These spaces provide refuge and travel lanes for insects, small mammals and even birds.
Explore the winter world by following a deer trail. Walk slowly and watch the surface of the snow for movement. A shrew or a weasel may appear briefly. You'll recognize a weasel by its elongated shape and inchworm-like loping gait. Find its escape hole, and it may lead you to the entrance of a chipmunk burrow. A dormant chippie is easy prey for a predator small enough to negotiate a chipmunk tunnel.
Nothing in nature, however, is foolproof, and life beneath the snow is not without risk. Foxes and coyotes hunt by sound. When they hear a rodent beneath the snow, they pounce. Their paws crash through the snow and trap the prey below.
Fields and woods can be eerily still and quiet after a winter storm, but appearances can be deceiving. Like the innards of a dead tree in spring, subnivia may be unseen, but it teems with life.
First Published January 6, 2013 12:00 am