Mountain wildlife readies for winter
It seems like every time I see a squirrel lately, it’s running around with a cone in its mouth. Autumn is the time of harvest for animals and they must build up food supplies to last them through the cold, lean winter.Eating is on everyone’s mind. Take the birds for instance. This year’s young are now juveniles and are growing fast, molting new, adult feathers and building fat reserves for the long journey south. It is not the season of singing birds, because attracting mates and establishing territories took place in the springtime. It is now time to quietly fill the fuel tank, and as other birds head south, there is less competition for local food. In response to the food shortages of winter, most birds migrate south to where food is still available, and the climate is milder.Golden-mantled ground squirrels are eating flower seeds like mad in order to build fat reserves to hold them through winter hibernation. We’ll see them for a couple more weeks before they hit the pillow, but when they do, we won’t see them again until the warm spring days of April.
Safe under the iceGround squirrels, along with marmots, are true hibernators. This means that their body temperatures drop below 40 degrees to minimize fuel consumption. True hibernators are so far from consciousness that they don’t even roll over the whole time they’re out. And if fat reserves are adequate, the animals will pop up through the snow on a warm, sunny spring day. But if fat reserve run out the animal runs out of fuel and will die. This is a good time of year to figure out which beaver lodges are active. The clever beavers harvest willow and aspen limbs and store them in a large pile called a food cache just outside their lodge in the middle of their pond. The bark is their food source, and they take limbs and push them into the mud on the bottom of the pond in order to keep them submerged. When the winter ice forms, the beavers can hold their breath for 15 minutes, drop out of the trap door under their lodge, swim to the food cache, and eat bark from under the ice where they are out of reach of predators.Beavers, as well as bears, go torpid during the winter months. Torpidity differs from hibernation in that body temperature drops only several degrees below normal. Although a torpid animal is a long way from full consciousness, it can wake up when it needs food and go out and forage. A true hibernator cannot wake itself up.Pikas are super-active near and above treeline this time of year. It is not uncommon to see them with little bouquets of flowers and vegetation in their mouths scurrying about near your feet.
The pikas have a strong instinct to gather, dry and store as much food as possible to hold them through the very long winter that lasts into June in the alpine. Pikas are awake in their burrows beneath the rocks and snow during the winter, nibbling on the stored food to keep them alive. If the food runs out they either have to turn into thieves and steal from other’s food caches or starve. For this reason, individual pikas fiercely protect their food caches – it is a matter of life and death.Bigger crittersBlack bears are out foraging 20 hours a day this time of year, and consume about 20,000 calories a day. Bears love berries but can also consume leaves, buds, twigs, seeds, insects, fish and small mammals. Bears will search out a denning site – such as a cave, crevice or under fallen trees – and will spend the winter there drawing off of stored fat reserves.Other large mammals such as elk, deer and bighorn sheep are also thinking about the coming winter. These animals will migrate from the high country down to moderate elevations.
They must store fat as well, because their winter forage contains only a fraction of the nutrients of summer forage. Autumn is also a physically stressful time of year for the dominant males as they compete with other males for breeding. Sometimes this leads to severe fatigue and weight loss in early winter, and the stress of it may cost them their lives during the lean season.If we humans were natural animals living in the wilds, we too would be gathering and storing foods. We’d be drying and preserving meats and fish, gathering berries and seeds, and sewing animal hides for warm clothing. We’d make sure we had plenty of dry firewood in stock as well. As modern people, instead of storing fat, we save our money to pay our heating bills. One advantage we have here in the Vail Valley is that it’s a fat winter, rather than lean.Tom and Tanya Wiesen are owners of Trailwise Guides; a year-round Vail Valley guide service specializing in daily private outings for hiking, mountain biking, snowshoeing, cross-country skiing, and natural history tours. Contact Trailwise at (970) 827-5363.Vail, Colorado