Spring is a time when long, warm days tell the hibernating animals it’s time to wake up from their winter slumber. This awakening to a conscious state is a major physical transformation for these animals.
Ground squirrels pop up through the snow, after not having rolled over for a full five months. Ground squirrels and marmots spend winter in a deep state of hibernation, where their body temperature drops radically and their metabolism lowers dramatically. They pull energy from their fat reserves, which they built up by feasting on vegetation the previous summer. However, if the animal didn’t fatten up enough for the winter, it runs out of fuel, and then dies in hibernation.
Beavers, on the other hand, do not hibernate as deeply. Instead, they go into a torpid state. The difference lies in that if they get hungry, part way through the winter, they can wake up and go out to find something to eat. Each autumn, the clever beaver establishes a food cache, just outside of their lodge. In the heart of winter, they exit the lodge through a trap door out the bottom, and swim out under the ice. There, pushed into the mud to keep it below ice-level, they find fresh willow and aspen branches. By staying beneath the ice, they reduce the chance of being preyed upon by a hungry coyote, or mountain lion.
Now that the creek ice is breaking up, watch for fresh beaver wood chips on top of the snow. Beavers will cut down willows, aspens, alders, or cottonwoods, and then drag them back to their pond. In the safety of the pond, they eat the bark, and with the left over wood, they add it to their dam or lodge. Remember, beavers don’t actually consume the wood, only the bark.
Bears, too, are now waking up, and like beavers, bears go torpid. Researchers have actually entered bear dens in the winter, and the bears only look at them with a glazed look, but don’t react otherwise. Bears can wake up for periods this time of year, find something to eat, and then return to sleep until later in the spring, when more food is available. You can often find bear claw marks on aspen trees, because the springtime catkins on the aspens are a reliable early season food source.
A common theme with all wildlife is efficiency. Is it more efficient for an animal to be awake and forage, or is it more efficient for it to drop its metabolism, and be in a lowered state of consciousness to minimize its fuel consumption? For instance, elk and bighorn sheep build up precious fat reserves on plentiful summer time vegetation. During the winter, the withered plants, upon which they feed, provide only minimal nutrition. They require more calories to live, than their limited winter food sources can provide. Their fat reserves cover this deficit. This is why you often see elk, deer, and bighorn sheep laying down in the wintertime; they are simply conserving energy, in order to make it to springtime when new plants provide nutritious food.
If food sources are ample, wildlife store the food as fat. However, if the fuel supply runs short, an animal finds ways to conserve energy. Conservation is a critical part of a wild animal’s energy policy.
Tom and Tanya Wiesen are owners of Trailwise Guides; a year-round Vail Valley guide service specializing in hiking, mountain biking, and natural history tours. Daily private tours are available. Contact Trailwise Guides at (970) 827-5363.