Marmota caligata

Geographic Range

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).

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

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.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• tundra tundra
• mountains mountains

Physical Description

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.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

Mating occurs shortly after emergence in the spring. Typical mating behavior involves the male approaching the female, sniffing her (possibly to determine if she is reproductive), then mounting her dorsoventrally. The female, when mounted, lifts her tail and holds it to one side. Successful mounts may last 30 seconds to 8 minutes. Non-reproductive females usually fight against an attempted mount, while reproductive females are more tolerant (Barash 1989). Sniffing, fighting, and chasing are all examples of marmot reproductive behavior. Originally, northern populations of hoary marmots were thought to be predominantly monogamous, while southern populations were thought to be both monogamous and polygynous. Recent studies suggest that mating among hoary marmots is more flexible than previously thought, varying between monogamy and polygyny. This may reflect local variation and resource availability (Kyle et al. 2007).

• Mating System
• monogamous monogamous
• polygynous polygynous

Females reproduce every other year, with an average litter size of 3.3, range 2 to 5 (Barash 1989, Armitage 2003). Yearlings remain in their natal colony and disperse the following year as two-year-olds, which is the age of sexual maturity. The reproductive cycle lasts 10 weeks, and gestation lasts about 4 weeks. Estrous in reproductive females occurs about 1 to 2 weeks after emergence from the hibernation and only occurs once yearly (Barash 1989).

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

As the breeding season progresses, adult males and females become less closely associated. When the young of the year are born, females provide more parental care than males and are the most watchful during the two-week period of their young’s emergence (Barash 1989). Young of the year are born blind and naked, except for vibrissae and short hair on the muzzle, chin, and head. Crawling (backward and forward) and teat seeking are the first movements to occur (Armitage 2003). Young of the year are weaned between the third week of July and the first week of August. Even though adult males are larger than adult females, increases in size are relatively constant between sexes during development. Hair gradually develops from head to tail, and more rapidly on the back than on the belly (Armitage 2003).

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• post-independence association with parents

Lifespan/Longevity

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).

Behavior

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.

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.

• Key Behaviors
• terricolous
• fossorial fossorial
• diurnal diurnal
• motile motile
• hibernation hibernation
• social social

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.

Communication and Perception

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).

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

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).

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• flowers

Predation

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.

Ecosystem Roles

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).

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).

• Ecosystem Impact
• soil aeration soil aeration

Economic Importance for Humans: Positive

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).

• Positive Impacts
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

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

Conservation Status

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.

Other Comments

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).

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Danielle Gunderman (author), University of Alaska Fairbanks, Link E. Olson (editor, instructor), University of Alaska Fairbanks.

References

Armitage, K. 2003. Wild Mammals of North America: biology, management, and conservation . Maryland, USA: John Hopkins University Press.

Barash, D. 1989. Marmots: Social Behavior and Ecology . Stanford, California, USA: Stanford University Press.

Blumstein, D., K. Armitage. 1997. Does Sociality Drive the Evolution of Communicative Complexity? A Compartive Test with Ground-dwelling Sciurid Alarm Calls. The American Naturalist , 150: 179-200.

Bowman, W., T. Seastedt. 2001. Structure and Function of an Alpine Ecosystem: Niwot Ride, Colorado . USA: Oxford University Press.

Hall, E. 1981. The Mammals of North America, Second Edition . Caldwell, New Jersey, USA: The Blackburn Press.

Hansen, R. 1975. Foods of the hoary marmot on the Kenai Peninsula, Alaska. American Midland Naturalist , 94: 348-353.

Hoffman, R., J. Koeppl, C. Nadler. 1979. The relationships of the amphiberingian marmots (Mammalia: Sciuridae). Occasional Papers of the Museum of Natural History, University of Kansas , 83: 1-56.

Karels, T., L. Koppel, D. Hik. 2004. Fecal pellet count as a technique for monitoring an alpine-dwelling social rodent, the hoary marmot (Marmota caligata). Arctic, Antarctic, and Alpine Research , 36: 490-494.

Krajick, K. 2004. All Downhill from Here?. Science Magazine , 303: 1600-1602.

Kyle, C., T. Karels, C. Davis, B. Mebs, C. Clark, C. Strobeck, D. Hik. 2007. Social structure and facultative mating systems of hoary marmots (Marmota caligata). Molecular Ecology , 16: 1245-1255.

MacDonald, S., J. Cook. 2007. Mammals and amphibians of Southeast Alaska. The Museum of Southwestern Biology, Special Publication , 8: 1-191.

MacDonald, S., C. Jones. 1987. Ochotona collaris. Mammalian Species , 281: 1-4.

Steppan, S., M. Akhverdyan, E. Lyapunova, D. Fraser, N. Vorontsov, R. Hoffman, M. Braun. 1999. Molecular phylogeny of the marmots (Rodentia: Sciuridae): tests of evolutionary and biogeographic hypotheses. Systematic Biology , 48: 715-734.

Tyser, R. 1980. Use of substrate for surveillance behaviors in a community of talus slope mammals. American Midland Naturalist , 104: 32-38.