Distribution. From the Cascade and northern Rocky Mts. to Alaska. In locations where ranges overlap yellow-bellied marmots (e.g., Montana), hoary marmots are found at higher elevations.
Hoary marmot social organization varies geographically. In Alaska they live in monogamous social groups consisting of a pair of adults and pre-reproductive offspring. In the Rockies and Cascades, hoary marmots live in social organizations that resemble Olympic marmots (breeding male with two or three breeding females, non-breeding offspring from previous years). Hoary marmots are active about four and a half months each year. When females reproduce, litter size averages three pups. Their home ranges are relatively large for marmots (they can be around 10 hectares!) and marmots may wander around much of it in a day. Like their close relatives, the Olympic marmot, they have four alarm calls. Hoary marmot calls can be similarly described by the difference between the starting and ending frequencies. Calls may be ascending, descending, or relatively flat. Hoary marmots also trill. A summary of hoary marmot alarm calling is available. Hoary marmots can be easily seen in Mt. Rainier National Park around both the Sunrise and Paradise Visitor Centers.