Thinking Outside the Classroom: Winter’s here: who’s settling in, and who’s heading south?
December 31, 2012
Now that winter has finally arrived in Summit County, we are starting to see a change in our forests’ ecology. We see fewer chipmunks, deer, and bears and more moose, mountain goats, and bighorn sheep. All animals in the forest must make a decision when winter comes: should I stay or should I go? Either option requires a tremendous amount of preparation and energy from our local fauna. From migration and hibernation to building up resistance to Mother Nature’s forces, here’s what’s coming this winter for our furry and feathered friends.When we think about migration, birds are often the first animals that come to mind. We’ve all seen massive flocks fly over us at the first sign of a winter chill. A bird preparing for a migratory trip must accumulate so much reserve energy that it may take off with up to 50 percent of its total body weight in fat. Birds also face obstacles such as hunters, ever-fading resting habitats along their migratory routes, and limited food availability at their final destinations. One of the most impressive migration feats is that of the Eastern North Pacific gray whale. They swim a massive 20,000 km round trip from their southern breeding grounds off Baja California and their northern feeding grounds off Alaska. We don’t see too many gray whales around Summit County, of course, but we do see a lot of deer and elk. Instead of going south to escape the cold, deer and other ungulates go down in elevation to where there is available food. Because the Front Range typically gets less snow than us, it makes sense that these herbivores follow the food by heading downhill. The other option to migration is hibernation. The physiological changes that take place during hibernation are fascinating. By reducing their metabolic activity and decreasing their body temperature to just above freezing, hibernating animals are able to save energy by slumbering through the harshest part of winter. Bears are the most stereotypical hibernator, but other mammals such as chipmunks, ground squirrels, whitetail prairie dogs, and reptiles and amphibians such as rattlesnakes, copperheads, and northern black racers can also be found huddled together to keep warm in the winter months. If animals aren’t hibernating, then they’re building up resistances to snow and cold through physical or behavioral adaptations. One winter adaptation is growing more fur. Mountain goats can survive at extreme elevations throughout the year, so their winter adaptations allow them to live there without much competition from others. They have long, coarse, hollow guard hairs which provide incredible insulation, and underneath lies another 3-inch layer of soft, woolly underfur, which acts as a second thermal barrier by trapping warm air next to the body. Other physical adaptations include long legs in animals such as moose, who can more easily navigate in deep snow, and high foot-surface-to-body-weight ratio in lynx and snowshoe hares, who can more easily skim across snowy fields. Behavioral adaptations include living under the snow. This ecological niche is called the subnivean zone, and is where animals such as mice, voles, shrews, and lemmings stay insulated from harsh temperatures and wind. Thermal heat keeps the layer closest to earth warm (a balmy 32F) and the snow protects these small mammals from being seen by predators. By building tunnels underneath the snow, these mammals can gather food from a safe location and not freeze.As a citizen of Summit County, you are more likely to hunker down and pull out your ski schwag than to head to the beaches of Florida for the winter. If you do stick around, keep an eye out for the furry neighbors who decided to join you.Sarah Rosenkranz is a Program Instructor at Keystone Science School. To learn more about our programs, call us at (970) 668-4098 or visit our website, http://www.keystonescienceschool.org.