Olympic marmot (Marmota olympus)

KingdomAnimalia
PhylumChordata
ClassMammalia
OrderRodentia
FamilySciuridae
GenusMarmota (1)
SizeHead-body length: 46 - 53 cm (2)
Tail length: 18 - 25 cm (2) (3)
Weight5 - 7 kg (3)
Top facts

The Olympic marmot is classified as Least Concern (LC) on the IUCN Red List (1).

Like other marmots, the Olympic marmot (Marmota olympus) is a large, stocky rodent with short legs (4), and as a dweller of underground burrows it has powerful forelimbs with big claws for digging (4) (5). Compared to its stout body (3) and long, bushy tail (6), the wide head of this housecat-sized rodent is relatively small. The Olympic marmot, which is a member of the squirrel family (7), has rounded ears, large eyes, and big, prominent teeth (4).

As its name suggests, the Olympic marmot is only found on the Olympic Peninsula of Washington in the United States (2) (3) (7) (8) (9).

Marmot fur is thick, coarse and stiff, and varies in colour between species and seasons (4). The Olympic marmot, one of the largest of its kind (3) (8), has a drab brown coat in the spring (2) (3) (10), which bleaches to yellow in the summer (3) (10). As in some other marmot species, the Olympic marmot has a white nose (3), and it also sports a band of white fur between the eyes on the bridge of its snout (3) (11).

Male and female Olympic marmots are extremely similar in appearance, although the male is often larger than the female (3).

Like all other marmot species, the Olympic marmot has a variety of distinctive calls and whistles which are used to communicate with other colony members and alert them to the presence of predators. Of the four basic calls, the flat, monotonous calls are most common, with the trilled call being reserved for situations of great danger (7).

The Olympic marmot has a very restricted range, being found only in Olympic National Park, on the Olympic Peninsula of western Washington State, USA (2) (3) (7) (8) (9). Although this species is found throughout the upper slopes of the Olympic Mountains (2) (9), it is rare in the wetter south-western areas of the park (6).

Marmots typically inhabit alpine and subalpine meadows, and the Olympic marmot is no exception (12). This high altitude species (13) is generally found at elevations between 1,700 and 2,000 metres above sea level (3) (13).

The Olympic marmot prefers rocky scree slopes (3) (7) (8) and lush meadows (3) (8) (13), particularly those consisting of tall sedge communities containing numerous grasses, forbs and sedges. These meadows are often bordered by clumps of alpine fir trees (13), and usually experience long, snowy winters and short, warm, variable summers (13).

Olympic marmot colonies are frequently found on south-facing slopes, as the higher level of sun exposure causes the snow to melt more quickly, leading to a better availability of food for these large rodents (7).

Like most of the 14 marmot species (5), the Olympic marmot is a highly social animal (7) (10), living in groups of between 3 and 20 individuals within underground burrow systems (9). A typical Olympic marmot colony is composed of a male, two females and their young (5) (6) (7) (10). The young, known as pups (6), are usually a mixture of ages, and generally consist of a litter of yearlings and a litter of infants (7) (10).

The Olympic marmot is a diurnal species (4), foraging in the morning and afternoon for a variety of vegetation types (7). This species tends to favour fresh plant growth (6) (14), and grasses and forbs appear to be the most important components of its diet (7) (14). Roots, herbs, mosses, flowers and even the occasional insect are also eaten (7). Olympic marmots are capable of doubling their body weight during the summer, and they use up the copious amounts of stored fat during hibernation (6). Dry grasses are sometimes collected by the Olympic marmot and taken into the burrow system to be used as bedding or for food (7).

Before the start of each feeding period, the Olympic marmot visits the other burrows in the colony (7). This species has a series of face-to-face interactions which serve as a regular greeting ritual (10), and family members engage in nose-to-cheek greetings (7) (8), as well as grooming (8).

The Olympic marmot is only active during the months of June, July and August (7), and typically hibernates between September and May (3) (7) (8) (13). It is believed that Olympic marmots undergo two moults per year. The midsummer moult turns the coat almost black, while during hibernation the marmots become pale again, and emerge in the spring with yellow-brown fur (6) (13).

Shortly after emerging from hibernation, the mating season begins (10). Generally, a female Olympic marmot will have one litter every other year (5) (7) (8) (10) (14), but there is evidence that females may sometimes breed in consecutive years (9) (15). Between April and June, following a gestation period of around 30 to 32 days, a litter is born in a grass-lined nest (10). The average litter size of the Olympic marmot is four (7) (10). The young do not emerge from the nest until they are about one month old (10), and they remain with the colony until they are two years of age (5) (7) (8) (10). When they first emerge, the pups initially stay close to their burrows, but gradually stray further afield and become more active later in the summer (6).

During the last couple of decades, the Olympic marmot has declined in a number of areas within Olympic National Park (7) (9), and has even disappeared completely from about half of the well-studied colonies which had previously been continuously occupied for at least 40 years (9) (12).

The declines in Olympic marmot populations were originally thought to be a result of increased tourism and human disturbance, but more recent studies have found that these factors have not had a significant effect on marmot numbers (9) (12). Encroachment of trees into the meadows that this species inhabits has been named as a possible reason for the population declines (7), and predation by coyotes (Canis latrans) has also been highlighted as a principal threat to the Olympic marmot (6) (7) (9).

As a result of its narrow habitat requirements and its dependence on a complex burrow system, the Olympic marmot is unable to disperse to more suitable areas should conditions deteriorate, which poses a further threat to the species (12).

The Olympic marmot is a protected species in Washington (7), and more than 90 percent of its habitat is protected within Olympic National Park (6) (9). In response to concerns for this species, Olympic National Park initiated a monitoring programme in 2010, which enables volunteers to record the presence or absence of Olympic marmots in various meadows throughout the park (6).

Proposed conservation action for the Olympic marmot includes further research into the population trends of this species (1).

Find out more about the Olympic marmot:

Learn more about Olympic National Park:

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:
arkive@wildscreen.org.uk

  1. IUCN Red List (June, 2012)
    http://www.iucnredlist.org/
  2. Burt, W.H. and Grossenheider, R.P. (1998) A Field Guide to the Mammals: North America North of Mexico. Houghton Mifflin Harcourt, Boston.
  3. Kays, R.W. and Wilson, D.E. (2009) Mammals of North America. Princeton University Press, New Jersey.
  4. Burton, M. and Burton, R. (2002) International Wildlife Encyclopedia. Third Edition. Marshall Cavendish, New York.
  5. Macdonald, D. (2001) The New Encyclopedia of Mammals. Oxford University Press, Oxford.
  6. National Park Service - The Olympic Marmot: Ecology and Research (July, 2012)
    http://www.nps.gov/olym/naturescience/loader.cfm?csModule=security/getfile&PageID=413259
  7. MobileReference (2008) The Illustrated Encyclopedia of North American Mammals: A Comprehensive Guide to Mammals of North America. MobileReference, Boston.
  8. Bowers, N., Bowers, R. and Kaufman, K. (2007) Kaufman Field Guide to Mammals of North America. Houghton Mifflin Harcourt, Boston.
  9. Griffin, S.C.(2007) Demography and Ecology of a Declining Endemic: The Olympic Marmot. Ph.D. Thesis, University of Montana, Missoula, USA. Available at:
    http://marmota.cons-dev.org/marm/MARM/BIBMAR/BibpdfG/10798.pdf
  10. Nowak, R.M (1999) Walker’s Mammals of the World. The Johns Hopkins University Press, Baltimore.
  11. Edelman, A.J. (2003) Marmota olympus. Mammalian Species, 736: 1-5. Available at:
    http://www.science.smith.edu/msi/pdf/736_Marmota_olympus.pdf
  12. Griffin, S.C., Valois, T., Taper, M.L. and Mills, L.S. (2007) Effects of tourists on behavior and demography of Olympic marmots. Conservation Biology, 21(4): 1070-1081.
  13. Barash, D.P. (1989) Marmots: Social Behavior and Ecology. Stanford University Press, California.
  14. Feldhamer, G.A., Thompson, B.C. and Chapman, J.A. (2003) Wild Mammals of North America: Biology, Management, and Conservation. The Johns Hopkins University Press, Baltimore.
  15. Griffin, S.C., Taper, M.L. and Mills, L.S. (2007) Female Olympic marmots (Marmota olympus) reproduce in consecutive years. The American Midland Naturalist, 158(1): 221-225.