Olympic marmot
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Family:	Sciuridae
Genus:	Marmota
Subgenus:	Petromarmota
Species:	M. olympus
Binomial name
Marmota olympus (Merriam, 1898)
Range of the Olympic marmot
Synonyms
Arctomys olympus Merriam, 1898

The Olympic marmot (Marmota olympus) is a rodent in the squirrel family Sciuridae. Its close relatives include the hoary marmot and the Vancouver Island marmot. This species is indigenous to the alpine and subalpine meadows, fields, and slopes of montane talus on the Olympic Peninsula in the U.S. state of Washington. For this reason, the Olympic marmot was declared Washington State's state endemic mammal in 2009. Colonies of burrows are found in various locations in the Olympic Mountains and differ in size; some colonies can be home to as few as one marmot family, and some can have multiple families with up to 40 marmots. Female marmots reach sexual maturity at the age of three then produce litters of 1–6 every other mating season.

This marmot is about the size of a domestic cat. It can be identified by a wide head, small eyes and ears, stubby legs, and long, bushy tail. Its sharp, rounded claws aid it in digging burrows. The coat color changes with the season and with age, but an adult marmot's coat is brown all over with small whiter areas for most of the year. This species shows the greatest sexual dimorphism found in marmots, with adult males weighing on average 2.2 kg (4.9 lb) more than females. The Olympic marmot is considered a folivore; its diet consists mainly of a variety of meadow flora such as lilies, lupine, and other grasses, leaves, flowers, mosses, and roots. These marmots are known for being very sociable animals which often engage in play fighting and vocalize four different whistles to communicate. These marmots are no longer hunted by humans like they were in the 1950s, but are preyed on by coyotes, cougars, bobcats, black bears, and golden eagles. The Olympic marmot is considered a species of Least Concern by the IUCN Red List. They are protected by law in the Olympic National Park.

American zoologist and ethnographer Clinton Hart Merriam first described the Olympic marmot in 1898 as Arctomys olympus, from a specimen collected on the Sol Duc River.^[2][3] Later it was classified as subspecies olympus of Marmota marmota (which now only includes the Alpine marmot) by Rausch in 1953, before being treated again as a distinct species in the marmot genus by taxonomists starting with Hoffmann et al. in 1979.^[4] The species name olympus (Olympic in Greek) was given because this species is native to the Olympic Peninsula of Washington state.^[2] Before being recognized as a distinct species native only to the Olympic Peninsula, the Olympic marmot was thought to have originated as an isolated relict population of Marmota marmota or M. caligata in the Pleistocene ice-free refugia.^[1][5] The Olympic marmot deviates from the typical Petromarmota subgenus in the large shape of its mandible, in differences of the dorsal region, and having 40 chromosomes instead of 42, all of which are characteristics that resemble the subgenus Marmota. These disparities are also evident in the Vancouver Island marmot (M. vancouverensis), which evolved separately, but also occurs in a restricted range.^[6]

The Olympic marmot's head is wide with small eyes and ears; the body is stocky with stubby legs and sharp, rounded claws that facilitate digging;^[7][8] the tail is bushy and ranges from 15 to 25 cm (6 to 10 in) long.^[9] The Olympic marmot is about the size of a domestic cat; adults weigh from 3.1 to 11 kg (6.8 to 24.3 lb) and are from 67 to 75 cm (26 to 30 in) in length, with the average being 71 cm (28 in). It is the largest marmot, about 7% longer than the hoary and Vancouver Island marmots. This species has the greatest sexual dimorphism found in marmots, with adult males weighing on average 9.3 kg (21 lb) and adult females weighing 7.1 kg (16 lb). Both sexes lose 50% of their body mass over the seven to eight months of winter hibernation. After this extreme weight loss, male marmots emerge from hibernation weighing approximately 4.1 kg (9.0 lb) and females weighing an average of 3.1 kg (6.8 lb).^[2]

The Olympic marmot has a double-layered coat consisting of soft thick underfur, for warmth, and coarser outer hairs. Infant marmots’ fur is dark gray in color; this changes in the yearling period to grayish brown with lighter patches. The adult coat is brown on the body with smaller white areas for most of the year, developing lighter brown patches during the summer. The first molt of the year occurs in June, commencing with two black patches of fur forming on the back of the shoulders; this black coloration then spreads to the rest of the body.^[10] In the fall, the coat is almost black but can fade to tan or even yellowish after surfacing from hibernation in the spring;^[11] the second molt is thought to occur during hibernation, explaining this change in the color of the fur. The Olympic marmot’s muzzle is almost always white, with a white band in front of the eyes.^[12]

The Olympic marmot can be readily distinguished from other species by coat color: it is brown all over, in contrast to the hoary marmot, which has black feet and a black spot on its head (but otherwise shares almost every other physical trait),^[13] and the Vancouver Island marmot, which has a very dark, almost black coat.^[14]

Olympic marmots are native to the Olympic mountains in the Olympic Peninsula of Washington State;^[9] in 2009, legislation was signed that declared the Olympic marmot to be Washington State's official endemic mammal.^[15] About 90% of Olympic marmots' total habitat is protected in Olympic National Park, where they are often sighted, especially on the Hurricane Ridge.^[16] Marmots are in decline in some areas of the park due to the encroachment of trees into meadows as well as predation by coyotes, and they are seldom seen in the wetter southwestern part.^[17]

The Olympic marmot's home range usually covers from half an acre to at most five acres;^[11] within the park, they inhabit burrows in lush sub-alpine and alpine meadows, fields, and montane scree slopes.^[12] Colonies of burrows are spread out in various locations of the mountains and differ in size; some meadows can contain as few animals as one marmot family, and some can have multiple groups of families with up to 40 marmots. There is a higher risk of inbreeding and death from random events in meadows with fewer marmots, making migration essential to the survival of the species.^[18] Burrows can be found at various elevations, ranging from 920 m (3,020 ft) to 1,990 m (6,530 ft); they are most often found in the range of 1,500 m (4,900 ft) to 1,750 m (5,740 ft).^[1] Burrows are multi-purpose structures, used for hibernation, protection from bad weather and predators, and to raise newborn pups;^[18] colonies of burrows are most frequently located on south-facing slopes as the snowmelt on these makes flora more available.^[1] These regions generally receive 75 cm (30 in) of rainfall per year, with most of this precipitation falling in the form of snow.^[19] The Olympic marmot is well-adapted to its generally cold natural habitat, where there is snowfall almost every month of the year on the mountain slopes and barren grasslands.^[18]

The habitats of the Olympic marmots stay at well-conditioned ecological levels owing to the marmots' diet and feeding habits; since the flora in these meadows is so healthy, there is an increase in the population of marmots. Cestodes and fleas use the Olympic marmot as a host, showing a secondary role for the marmot within its ecosystem.^[2]

Olympic marmots are gregarious burrowing animals. Activity patterns vary with the weather, time of day, and time of year; owing to rainfall and fog cover during the summer months of June, July, and August, the marmots spend most of the day inside their burrows, and forage for food and interact with other marmots only in the morning and evening. At these times Olympic marmots can sometimes be found lying on rocks where they sun themselves for warmth, grooming each other, playing, chirping, and feeding together.^[8][11] Marmots seldom move to other colonies with the exception of sub-adults of two to three years old, which may leave the home burrow to start a new family elsewhere;^[20] females only move a few hundred meters, though males often move several kilometers away from their birth burrow.^[18]

A typical family of marmots, called a colony, consists of a male, two to three females, and their young, sometimes living in groups of more than a dozen animals;^[7] young marmots stay with their family for at least two years, so a burrow is often home to a newly born litter and a year-old litter. A colony may also have a subordinate or "satellite" male; these subordinates may take over as the dominant male if the existing dominant male dies.^[2] These very sociable animals usually greet each other by touching noses or nose to cheek; in courtship rituals they may inter-lock teeth and nibble each others' ears and necks. They may also engage in play fighting, in which two marmots on their hind legs push each other with their paws; this play fighting is more aggressive between older marmots.^[2]

Olympic marmots communicate physically and vocally; they have four different types of whistles,^[21] differing in this from their close relatives, the hoary marmot and the Vancouver Island marmot.^[18] The Olympic marmot's whistles include flat calls, ascending calls, descending calls, and trills; all of these are in a small frequency range of about 2,700 Hz.^[2] Flat, ascending, and descending calls are most often voiced singly. The ascending call has a duration of about half a second, starting with a "yell" on one note and ending with a "chip" on a higher note; it is often used as a distress or warning call for unfamiliar smells and noises. These same "yips" are heard when Olympic marmots are play fighting, along with low growls and chattering of teeth. The descending call ends on a lower note than it started on. The trill, which sounds like multiple ascending calls put together as one longer sound, consists of multiple ranging notes and is voiced as an alarm call to communicate to other marmots in the area that danger may be approaching and they should return to their burrows. Females with young have the responsibility to watch out for their young and other relatives near the burrow, and therefore voice the trill more often than other Olympic marmots. If marmots are not accustomed to human contact in a certain area, they may also sound a trill when seeing a person,^[21] in order both to alert other marmots and to tell the hiker that he or she is in the marmots' territory.^[11] At places like Hurricane Ridge, where seeing humans is a frequent occurrence, most marmots will not acknowledge human presence at all.^[21]

Olympic marmots communicate through the sense of smell to mark their territory. A gland located in their cheek exudes chemicals which they rub on scenting points, such as shrubs and rocks, to indicate possession; this can be smelt by other marmots in the area.^[2]

Olympic marmots hibernate from September through May to June; adults emerge from hibernation in May and young animals in June. Prior to hibernation, the marmots bring dry grasses into the burrow for bedding or food.^[2] Hibernation is the most dangerous time for the Olympic marmot as, in years of light snowfall, as many as 50% of the young born that year will die from the cold due to the lack of insulation which is provided by a good snow cover.^[2] Olympic marmots are said to be "deep hibernators" as they cannot easily be awoken; their body temperature drops to below 40 °F (4 °C) and heart rate can slow to three beats per minute. They do not eat during hibernation having stored fat beforehand, but they do warm their bodies about every 10 days.^[18] When Olympic marmots emerge from hibernation early in May thick snow cover is still present from the preceding winter, so they are not very active at this time.^[22]

The Olympic marmot is a folivorous (leaf-eating) animal, eating meadow flora species in the Olympic Peninsula, such as avalanche and glacier lilies, heather blossoms, sub-alpine lupine, mountain buckwheat, harebells, sedges, and other grasses, leaves, flowers, mosses, and roots.^{[2][18][7][8][11]} They prefer green, tender, flowering plants over other sources of food, but roots are a large part of their diets after hibernation when other plants and flowers have not yet bloomed.^[8] At this time, during May and June, they will resort to gnawing on trees for food;^[11] they will also occasionally eat fruits and insects.^[7] Their water requirements are met from the juice in the vegetation they eat and dew on the plants' surfaces. During the winter when snowfall covers the vegetation marmots eat a more carnivorous diet, picking up small dead animals such as Townsend's chipmunks, and obtaining water from melted snow.^[2] Hibernating Olympic marmots do not keep food in their burrows; they gain fat before hibernating and can double their body weight to survive eight months without eating.^[1][11]

A female Olympic marmot has a litter of from one to six young in alternate years.^[23] About 30–35% of females have a litter each year, and half of the pups die before the following spring.^[18][11] Neither males nor females reach sexual maturity until they are three years old, but females generally do not reproduce until they are four and a half years old.^[18] The marmot comes out from hibernation at the beginning of May, and estrus occurs about two weeks later. After hibernation ends, both male and female Olympic marmots attempt to entice the opposite sex with courtship rituals. Females who have never produced a litter before tend to be more aggressive and will chase or instigate fights with males; females which have already produced young tend to greet the male with nasal to nasal or nasal to genital contact, with copulation following shortly afterwards. This approach is more successful than the aggressive manner of the non-parous female, with mating taking place within 11 to 20 days after hibernation. The relationship between a sexually mature male and female Olympic marmot is polygynous; males tend to breed with three or four females in each mating season.^[7]

Approximately four weeks after mating, the female gives birth to her young in a grass-lined burrow underground. Newborn pups cannot see, have no fur, and are pink in color.^[7] Mothers nurse their young until 10 weeks of age, then start introducing them to a more adult diet including various flora. This process is called weaning. It is about a month before the young Olympic marmots first leave the burrow; even after they are allowed to emerge, the mother stays within a few meters of her young and prevents them from roaming far from the burrow. When pups are out of the burrow but still not old enough to be foraging for themselves, they can be found chasing each other and wrestling playfully.^[11] Olympic marmots are not completely independent from their mothers until they reach 2 years of age.^[2] Breeding-age female marmots are extremely important to marmot populations. If a female of breeding age dies it can take years to replace her; marmots can usually only have a maximum of six pups in a litter, the maturation period is long, and many marmots die before reaching maturity.^[18] Only about half the pups born survive their first year.^[13]

In common with all other marmots, Olympic marmots use the trill as an alarm call to alert other marmots to predators.^[21] These include terrestrial animals and avian raptors, such as coyotes, cougars, bobcats, black bears, and golden eagles.^[24] It would appear that bears rarely prey on marmots, as their presence close to colonies frequently does not raise alarm calls.^[25] Foxes are not native to the Olympic National Park.^[26] The coyote is the primary predator and studies have shown that marmots make up approximately 20% of coyotes' diet during the summer months. There is heavy predation by coyotes in warm winters, which could affect populations as the climate changes: lower banks of snow allow coyotes to move up higher on mountains where marmots dwell, into areas which they could not usually reach during an average cold winter. Those marmots that evade the predators can live into their teens.^[18]

Sightings of land predators, coyotes in particular, receive more alarm calls than aerial predators. Continuing alarm calls indicate that a predator is close, and thus increase vigilance in the marmots; a single alarm call results in the marmots still curiously looking around for the predator.^[21] As humans in the Olympic National Park do not hunt the marmot, but simply observe them, they do not pose a threat. When researchers intrude on colonies to observe behavior, the families living in burrows there initially vocalise with ascending calls, showing surprise, but then adjust to the presence of humans, allowing observation and studies.^[1]

The Olympic marmot is the second-rarest North American marmot, but it is considered a species of Least Concern by the IUCN Red List.^[1][18] Living in such a small geographic range is to their advantage as they are protected by law in Olympic National Park.^[2] The total population was thought to be only about 2,000 in 1989, but in more recent studies it was found to be about 4,000; this increase is due not to population growth, but to improved data collection.^[1] When concerns arose about the decline in numbers, volunteers started to collect and store data about marmot populations in the park through a monitoring program which started in 2010.^[11]

Olympic marmots were first recorded in the Olympic Peninsula in the 1880s, when biologists began research expeditions in the Olympic mountain area. Humans paid more attention to the marmots in the 1950s; marmots were eaten, collected for museums, and shot by hikers, explorers, and scientists. Despite this, David P. Barash reported after his three-year study of Olympic marmots in the 1960s that there was still an abundance of marmots in the mountains. Little further research was done on the Olympic marmot until the late 1990s, when concerns arose about population status; rangers and frequent visitors to the Olympic National Park had noticed that some populations of Olympic marmots had disappeared from their usual habitats. In 2002 the University of Michigan began a population study; marmot population continued to decline by about 10% a year until 2006. Many studies proved that, during this time, predation by coyotes (which had not been present in the area before the 20th century) was the main cause of death of females, inhibiting population regrowth. By 2006 numbers had dropped to 1,000 individuals; this figure increased from 2007 to 2010, when colonies stabilized and survival rates rose.^[18][16][27]

Olympic marmots are readily affected by climate change because of their sensitivity to changed habitats. When meadows in Olympic National Park dried out, marmots there died or moved.^[11] In the long term, meadows may be superseded by forests. Climate change will alter the timing, composition, and quality of the marmots' food. Olympic marmots can become more vulnerable to predators when daytime temperatures rise too high for foraging, causing them to forage in the cooler evenings when predators are more difficult to notice. Climate change could also have positive effects; a warmer climate would result in a longer growing season in which marmots could grow quickly and mature earlier, and thus breed more frequently throughout the year.^[18]

• Barash, David P. (1989). Marmots: Social Behavior and Ecology. Stanford, California: Stanford University Press. ISBN 9780804715348. {{cite book}}: Invalid |ref=harv (help)
• Griffin, Suzanne Cox (2007). Demography and ecology of a declining endemic: The Olympic marmot. ProQuest. {{cite book}}: Invalid |ref=harv (help)
• Witczuk, Julia J. (2007). Monitoring Program and Assessment of Coyote Predation for Olympic Marmots (PDF) (M.S. thesis). Missoula, MT: The University of Montana. Retrieved December 29, 2011. {{cite thesis}}: Invalid |ref=harv (help)

• Media related to Marmota olympus at Wikimedia Commons