On the Alpine Tundra


Yellow-bellied marmots are dark brown grizzled with yellow and with yellowish bellies. Tails are bushy. They have an average body length of about 2 feet and weigh between five and ten pounds. Marmots live in burrows or dens and spend only about 20% of their lives in the open on rocky hillsides and talus slopes. They feed on green vegetation, but if food becomes really scarce, they will take a few insects. During the summer they must breed and produce young in time for the litter to grow big and fat before hibernation begins again (often late August-early September). An average litter is about five young.

Marmots are communal animals, living in a family unit that consists of a single adult male and a harem of several adult females, several yearlings, and litters of young. This system allows increased safety, since many pairs of eyes are available to spot predators. In summer, coyotes and foxes visit the tundra, and hawks and eagles fly overhead watching for young, fat marmots. A whistle of alarm will send marmots scurrying for cover among the rocks. Second year young disperse to set up new colonies, which controls the population in a territory and helps to provide an adequate food supply.

Several burrows or dens under rock piles are available for nurseries, resting places in day or night, hiding places, and places to hibernate during those long winter months. Protected by good layers of fat and huddled together in dens, marmots slip into a dormant state that conserves energy, with body temperatures only a few degrees above freezing. They emerge only when the warmer temperatures of spring bring them gradually out of their dormancy so that by the time they are really awake, they can find food outside the den and not just snow.

At first glance the tundra appears to be a barren land, but it nurtures its own forms of life and in summer the rich grasses and sedges provide grazing for Rocky Mountain sheep and herds of elk. A couple of weeks ago, daughter Anna and I were driving across Trail Ridge road from west to east. It was nearly dark. The afterglow in the western sky had turned a lovely orange above the black silhouette of mountain peaks. We came to a place where the road follows a huge S curve, across a wide, sloping meadow. I think it was the area in this

The copyright of the article On the Alpine Tundra in Colorado is owned by B. J. Barton. Permission to republish On the Alpine Tundra in print or online must be granted by the author in writing.

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