Hoary Marmot

The hoary marmot is a large, bulky, ground squirrel, with short, heavy limbs, and a broad head. Adults range from 62 to 82 cm (24 to 32 in) in total length, including a 17 to 25 cm (6.7 to 9.8 in) tail. The species is sexually dimorphic, with males being significantly larger than females in most subspecies. Because of their long winter hibernation, during which they survive on fat reserves, the weight of the animals varies considerably over the course of the year, from an average of 3.75 kg (8.3 lb) in May to around 7 kg (15 lb) in September, for a fully grown adult. A few fall adult males can commonly range up to a weight of 10 kg (22 lb). The record sized autumn male specimen attained a mass of nearly 13.5 kg (30 lb), possibly the largest size known for any marmot. Going on its average size relative to other marmot species, it is slightly smaller on average than the Olympic marmot, similar in size to the Vancouver Island marmot and broadly overlaps in size with several lesser-known Asian marmot species as well. 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, and grizzled black or brown fur elsewhere. …

The hoary marmot predominantly inhabits mountainous alpine environments to 2,500 metres (8,200 ft) elevation, although coastal population also occur at or near sea level in British Columbia and Alaska. Hoary marmots occur from southern Washington and central Idaho north, and are found through much of Alaska south of the Yukon River. They live above the tree line, at elevations from sea level to 2,500 metres (8,200 ft), depending on latitude, in rocky terrain or alpine meadows dominated by grasses, sedges, herbs, and Krummholz forest patches. Range maps often erroneously depict hoary marmots occurring north of the Yukon River in Alaska, this region is occupied by the Alaska marmot (M. broweri) and not the hoary marmot. Hoary marmots also occur on several islands in Alaska and fossils dating back to the Pleistocene, including some from islands no longer inhabited by the species. The three currently recognized subspecies are:

M. c. caligata – Alaska, Yukon, NW Territories, northern British Columbia M. c. cascadensis – Coast Mountains, British Columbia to the Cascade Mountains in Washington M. c. okanagana – Rocky Mountains, from Yukon to Montana and Idaho

Hoary marmots are diurnal and herbivorous, subsisting on leaves, flowers, grasses, and sedges. Predators include golden eagles, grizzly and black bears, wolverines, coyotes, red foxes, lynxes, wolves, and cougars. They live in colonies of up to 36 individuals, with a home range averaging about 14 hectares (35 acres). Each colony includes a single, dominant, adult male, up to three adult females, sometimes with a subordinate adult male, and a number of young and subadults up to two years of age. The marmots hibernate seven to eight months a year in burrows they excavate in the soil, often among or under boulders. Each colony typically maintains a single hibernaculum and a number of smaller burrows, used for sleeping and refuge from predators. The refuge burrows are the simplest and most numerous type, consisting of a single bolt hole 1 to 2 metres (3 ft 3 in to 6 ft 7 in) deep. Each colony digs an average of five such burrows a year, and a mature colony may have over a hundred. Sleeping burrows and hibernacula are larger and more complex, with multiple entrances, deep chambers lined with plant material, and stretching to a depth of about 3.5 metres (11 ft). …