The marmot is the largest of our ground squirrels, a close relative of the woodchuck of the East and Midwest.
The yellow-bellied marmot is a heavy-set, grizzled brown animal with white patches on the chin and (as the name suggests) a yellowish belly. Marmots can be waddling fat in the fall, and their long fur makes them look even fatter. Adults are about 26 inches long and weigh up to about 11 pounds.
Predators include the coyote, badger, bobcat, golden eagle, hawks, owls, weasels and marten. However, predation probably is a less important cause of mortality than is the stress of hibernation. Marmots are protected by a rocky habitat and a social system of alarm calls.
Range: Marmots are widespread in western North America. Marmots are often associated with alpine meadows, but they actually live in suitable habitat down to the lower foothills.
Habitat: Marmots burrow deep into the soil beneath boulders to den. Up to half of their summer weight is lost during hibernation; animals with insufficient fat, or a burrow too shallow to prevent freezing, do not arouse in the spring.
Diet: Preferred foods are flowering stalks, but marmots eat the leaves of a variety of grasses and forbs.
Reproduction: After hibernation, the marmot emerges to mate as soon as green forage is available. After a 30-day gestation period, approximately five offspring are born. They are weaned at 20 to 30 days. A single male maintains a territory with a harem of several females, yearlings, and young of the year.
By David M. Armstrong
Department of Ecology & Evolutionary Biology
Environmental Studies Program, University Museum of Natural History
University of Colorado-Bouldermausmann@aol.com