Marmota caligata
hoary marmot

Hoary marmots are one of the most widespread alpine mammals in North America, ranging from Alaska south through northwest Canada to Washington, Idaho, and Montana (Karels et al. 2004). They have a wide distribution in Alaska, including the Alaska Peninsula, Alaska Range, and White Mountains. In Canada, hoary marmots inhabit the Ogilvie Mountains in the Yukon Territory. They are found in the Cascades Mountain range, northern and central Rocky Mountains, the Beaverhead and Flint Creek Mountains of northwestern Montana, and the Salmon River mountains of central Idaho (Hoffmann et al. 1979). (Hoffman, Koeppl, and Nadler, 1979; Karels, Koppel, and Hik, 2004)

Hoary marmots occupy areas with rocky talus slopes and alpine tundra vegetation (Kyle et al. 2007) and dig their burrows in these areas. Burrows provide shelter from predators and weather, marmots spend about 80% of their lives in them (Barash 1989). Entrances to marmot burrows are not easily identified because they simply appear as spaces between and/or under large boulders (Karels et al. 2004). The elevational range of hoary marmot habitats varies latitudinally; they are found at sea level in Alaska and only at higher elevations in the southern portions of their range. (Barash, 1989; Karels, Koppel, and Hik, 2004; Kyle et al., 2007)

Hoary marmots weigh 8 to 10 kg and are from 45 to 57 cm in length, with males being slightly larger than females (Kyle et al. 2007). Tail length is 7 to 25 cm. Their coats are mostly black and white with hoary tips to the fur, base fur color varies geographically (Barash 1989, Hoffmann et al. 1979). They have a white patch between the eyes and across the rostrum, and the tips of their noses are white. Hoary marmots differ from other marmots in that they have black feet. This is the basis of the species’ name caligata, which means “booted” (Hoffmann et al. 1979). They also have a black cap on their head that is larger than similar caps found in other species of marmots. Marmots generally undergo a single annual molt. The onset of the molt varies, but can happen as soon as emergence from hibernation. By midsummer, molting is advanced in all individuals except the young of the year (Barash 1989). Hoary marmots have small eyes and small, rounded, furred ears. They have well-developed claws on their front feet for burrowing and 5 pats on their forepaws, 6 on their hind paws. (Barash, 1989; Hoffman, Koeppl, and Nadler, 1979; Kyle et al., 2007)

Weight at hibernation is significantly related to overwinter mortality, which is highest among young of the year. Winter mortality during hibernation is often more predictable than predation, and the mortality of males is higher than that of females (Barash 1989). (Barash, 1989)

Hoary marmots are highly social animals, and greeting is a frequently exhibited behavior. The exact function of greeting is unknown, but it is thought to be involved in recognizing individuals. Greeting is frequent after the animals emerge from their burrows, and begins with nose-to-nose or nose-to-mouth contact. Adult males and young of the year initiate most greetings (Barash 1989). Marmots live in colonies. The basic social structure of a colony consists of one adult male, one satellite male, one or more adult females, two-year-olds, yearlings, and young of the year. In order to avoid the dominant male, satellite males are more likely to occur in colonies located in large meadows. Because marmots are social animals, they also tend to play. Play fighting is common among young and yearlings (Barash 1989). In addition to social behavior, hoary marmots exhibit surveillance behaviors. Approximately 30% of time above ground is spent on surveillance, with looking up and looking out while sunning the two most popular behaviors (Tyser 1980). Look-up and upright-alert postures usually occur during foraging and tend to be associated with rock size. (Barash, 1989; Tyser, 1980)

Hoary marmots hibernate during the winter. They emerge in mid-May, become lethargic by late August, and re-enter the burrows as early as early September. The onset of hibernation is gradual, with a steady decline in social activity, foraging, and time spent above ground (Barash 1989). All members of family groups hibernate together (Kyle et al. 2007). In the summer, activity above ground peaks in the morning and late afternoon. Marmots may facilitate their energy intake by adjusting their behavior to capture radiant energy during low temperatures. They do this by sunning themselves on rocks and sprawling on the ground near their burrows. On sunny days in July hoary marmots spend 44% of their above ground time in early morning sunning themselves (Barash 1989). In the early spring, late summer, and in inclement weather, above-ground activity only peaks at midday. (Barash, 1989; Kyle et al., 2007)

Home Range

Home range sizes vary regionally and with local food availability. Areas with poor forage may make it impossible for males to control family groups because individuals are too widely dispersed.

Hoary marmot alarm calls tend to be loud, relatively short, and are associated with predators or agitation (Barash 1989, Blumstein and Armitage 1997). Hoary marmots also use visual signals to communicate. The clearest visual signal is an upraised tail, which appears to signal aggression towards other members of the colony (Barash 1989). (Barash, 1989; Blumstein and Armitage, 1997)

Hoary marmots are mostly herbivorous. Vetches, sedges, fleabanes, fescues, mosses, lichens, and willows collectively comprise about 90% of the overall diet of populations living on the Kenai Peninsula, while populations from mountainous regions prefer flowers and flower heads (Barash 1989, Hansen 1975). Marmot populations from different regions have similar diet-habitat characteristics even if less plant biomass is available. Hoary marmots do not select vegetation in proportion to the amount available, but rather show a preference for certain plants. Hoary marmots spend most of their above-ground time foraging. They appear to prefer each other’s company, feeding in groups. Feeding groups of up to 8 animals can occur. However, these groups are loosely organized and dynamic in terms of membership (Barash 1989). (Barash, 1989; Hansen, 1975)

Hoary marmots are eaten by a variety of predators, including golden eagles, lynx, coyotes, grizzlies, and wolverines. Predator avoidance appears to exert a strong influence on foraging patterns, and marmots have been known to remain in their burrows for many hours following the appearance of a predator (Barash 1989). They also use alarm calls to alert one another if a predator has entered their foraging area. (Barash, 1989)

Hoary marmots are good candidates as indicator species because alpine ecosystems are particularly vulnerable to climate change (Krajick 2004). Compared to other alpine species, they have little commercial value in North America and hardly experience any human-related mortality. Changes in their populations could be indicative of other large-scale impacts. Long-term population dynamics of hoary marmots may also provide an indication of changes in alpine snowpack, plant phenology and abundance, or predators (Karels et al. 2004). (Karels, Koppel, and Hik, 2004; Krajick, 2004)

The feces of hoary marmots are important to pikas, which have been observed consuming these droppings. Dried fecal pellets of hoary marmots have been found in haypiles made by pikas (MacDonald and Jones 1987). Marmot feces may be important for soil as well. Soil surrounding marmot burrows is thought to be quite high in nutrients because marmots tend to deposit fecal matter in these areas (Bowman and Seastedt 2001). (Bowman and Seastedt, 2001; MacDonald and Jones, 1987)

There are no known negative impacts associated with hoary marmots. Hoary marmots inhabit areas with low human population densities.

Hoary marmot hides were prized by northwestern Native Americans, mainly for clothing. Marmots were hunted after the molt, and their hides were used in potlatch ceremonies. Their hides were also used as a sort of currency, measuring wealth among Tlingit and Gitksan tribes (Armitage 2003). (Armitage, 2003)

Hoary marmots have a stable population trend and are considered a species of least concern. The state of Alaska, however, considers two subspecies of hoary marmots to be of conservation concern: Montague Island marmots (M. c. sheldoni) and Glacier Bay marmots (M. c. vigilis). Montague Island marmots were last seen at the turn of the 20th century and are considered a species of concern because of lack of sightings. Because these marmots are endemic to Montague Island, they may face a higher risk of extinction. The state of Alaska also considers Glacier Bay marmots to be a subspecies of concern due to its endemism and presumed small population size. In addition, there is lingering taxonomic uncertainty regarding both of these subspecies. (MacDonald and Cook, 2007)

Recent studies have shown that fecal pellet counts can provide an accurate estimate of group size in hoary marmots, thus allowing for better monitoring of population changes (Karels et al. 2004). (Karels, Koppel, and Hik, 2004)