Hoary marmots are largest North American ground squirrels. The word "hoary" refers to the silver-gray fur on their shoulders and upper back; the remainder of the upper parts have drab- or reddish-brown fur. The head is black on the upper surface, with a white patch on the muzzle, white fur on the chin and around the lips. The feet and lower legs are black, sometimes with white patches on the forefeet. The tail is long, slightly flattened, and covered with dense fur.
Hoary marmots are found in northwest North America. They occur from southern Washington and central Idaho north, and are found through much of Alaska south of the Yukon River. These animals inhabit mainly mountainous alpine environments, in rocky terrain or alpine meadows dominated by grasses, sedges, herbs, and Krummholz forest patches.
Hoary marmots are diurnal being active during the day. They live in colonies of up to 36 individuals. Each colony includes a single, dominant male, up to 3 females, sometimes with a subordinate adult male, and a number of young and subadults up to 2 years of age. These marmots hibernate 7-8 months a year in burrows they excavate in the soil, often among or under boulders. Each colony typically maintain a single burrow for hibernation and a number of smaller burrows which they use for sleeping and refuge from predators. Each colony digs an average of 5 such burrows a year, and a mature colony may have over a hundred. Closer to hibernation time Hoary marmots like to socialise through play fighting, wrestling, social grooming, and nose-to-nose touching. These animals use at least seven distinct types of calls, including chirps, whistles, growls, and whining sounds. Many of these calls are used as alarms, alerting other animals to potential predators.
Hoary marmots are usually monogamous, mating with the same partner more than once. However, southern populations are suggested to be both monogamous and polygynous. These marmots breed shortly after hibernation in May and in some areas (such as the eastern Cascade foothills of Washington State) as early as February. Females give birth to 2-5 young between late May and mid-June. The gestation period usually lasts 25 to 30 days. The young emerge from their birth den at 3-4 weeks of age, by which time they are fully furred and are already beginning to be weaned. Subadults remain with their birth colony but typically leave at 2 years of age. They reach reproductive maturity the following year.
There are no major threats to Hoary marmots at present.
According to IUCN, the Hoary marmot is locally common and widespread throughout its range but no overall population estimate is available. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.