Hoary Marmots prefer treeless meadows with rocky outcrops and talus. They forage on forbs, grasses, and sedges. They tend to be gregarious. Groups of 5-8 feed together, with frequent bouts of greeting and grooming. As soon as they emerge from hibernation, in May, they mate. The young-of-the-year appear aboveground in July and have a short first year of activity. In September they disappear into hibernation, not to emerge until the following spring. The marmots become sexually mature when they are three years old, and from then on, females usually have a litter of 2-4 every other summer.

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Mammal Species of the World