Marmota olympus

Olympic Marmots are highly social, living in groups made up of an adult male, one or more adult females, two-year-olds, yearlings, and young. Their diet consists of grasses and sedges, with flowering plants in season. Coyotes, martens, and eagles prey upon Olympic Marmots. Their range is very restricted; they are found only on the Olympic Peninsula of Washington State, in alpine and subalpine meadows at elevations of 1,700-2,000 m.

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Mammal Species of the World

The species' range is limited to the upper slopes of the Olympic Mountains of western Washington (Edelman 2003); the species is almost completely restricted to Olympic National Park (Barash 1973). The extent of occurrence is approximately 1,800 square kilometers (Barash 1973). Most marmots occur at elevations of 1,500-1,750 m asl, with normal lower and upper extremes of 920 and 1,990 m asl (Barash 1973) and rare occurrences to near sea level (30-200 m asl) (Scheffer 1995).

Olympic marmots, Marmota olympus, are found almost exclusively in the Olympic National Park on the Olympic Peninsula in the state of Washington (USA).

Biogeographic Regions: nearctic (Native )

endemic to a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (1000-5000 square km (about 400-2000 square miles)) The range is limited to the upper slopes of the Olympic Mountains of northwestern Washington (Edelman 2003); the species is almost completely restricted to Olympic National Park (Barash 1973). Extent of occurrence is approximately 1,800 square kilometers (Barash 1973). Most marmots occur at elevations of 1,500-1,750 meters, with normal lower and upper extremes of 920 and 1,990 meters (Barash 1973, Wood 1973) and rare occurrences to near sea level (30-200 meters) (Scheffer 1995).

Olympic marmots are, on average, larger than other marmots. They are approximately 7% longer than Marmota caligata and Marmota vancouverensis. Olympic marmots exhibit sexual dimorphism; on average, adult males weigh 9.3 kg while adult females weigh 7.1 kg. Body mass is seasonally dependent in both sexes, and individuals lose about 50% of their total body weight during the 7 to 8 months of winter hibernation. When they emerge from hibernation, adult males weigh an average of 4.1 kg while females weigh an average of 3.1 kg. Both young males and females (1 to 2 years in age) lose approximately the same percentage of body mass, though their total mass is lower than that of adults.

Olympic marmots have 2 types of fur covering their body: soft dense underfur that keeps them warm and coarser outer fur. Their ears, tail, face, and legs are also covered in fur. They are generally brown with intermixed white, but pelage color is often seasonally dependent. On emerging from hibernation, their fur is yellow/brown in color. Infants are dark gray in color while yearlings are grayish brown with some lighter patches of fur. Olympic marmots molt twice during the year. The first molting occurs in June when two black patches of fur develop on the back of the shoulders of an adult and subsequently spread to the rest of the body. The second molting is thought to occur during during hibernation, as adults emerge in the spring with lighter fur. While Olympic marmots are similar in appearance to hoary marmots and Vancouver marmots, hoary marmots have black feet and a black spot on their head, and Vancouver marmots are almost completely black in appearance.

Range mass: 3.1 to 11.0 kg.

Range length: 670 to 750 mm.

Sexual Dimorphism: male larger

Length: 78 cm

Sexual Dimorphism: Males are larger than females.

Length:
Range: 680-785 mm

Weight:
Range: 5-7 kg

Hoary marmot (M. caligata) has bold black and white pattern on the head and front part of the body. Woodchuck (M. monax) is uniformly grizzled blackish or dark brown on the head and upper body. Yellow-bellied marmot (M. flaviventris) has prominent yellowish patches on the sides of the head and neck, and buffy or pale feet (Whitaker 1996).

Habitat and Ecology

Systems

• Terrestrial

Olympic marmots primarily occupy sub-alpine and alpine meadows as well as talus slopes. The are generally found at elevations of 1,500 to 1,750 m but have been observed at elevations as low as 3 m and as high as 1,990 m. The alpine meadows and subsequent area include avalanche lilies (Erythronium montanum), mountain buckwheat (Polygonum bistortiodes), as well as sub-alpine lupine (Lupinus subalpinus). This region is characterized by large amounts of rainfall, averaging 75 cm per year. Most of the annual precipitation falls in the form of snow.

Range elevation: 30 to 1,990 m.

Average elevation: 1,500 to 1,750 m.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest ; mountains

Comments: Typical habitat encompasses subalpine and alpine meadows and talus slopes near timberline; many colonies are located on south-facing slopes, where food availability is probably greater because of earlier snowmelt (Barash 1973). Young are born in underground burrows.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Olympic marmots are folivorous, consuming meadow flora species found on the Olympic Peninsula including avalanche lilies (Erythronium montainum), sub-alpine lupine (Lupinus subalpinus), mountain buckwheat (Polygonum bistortoides), Arenaria capillaris and harebells (Campanula rotundifolia) along with other grasses, flowers and roots. Olympic marmots have also been known to scavenge small, dead animals such as Townsend's chipmunks when snow is present and access to flora is limited. Olympic marmots rely on snow and glacial melt for their water supply. When these sources become unavailable, Olympic marmots are thought to obtain most of their water from the vegetation they consume, from water within the plant as well as dew on the foliage.

Animal Foods: carrion

Plant Foods: leaves; roots and tubers; flowers

Primary Diet: herbivore (Folivore )

Comments: Grazes on a wide variety of grasses and forbs. Does not store food for the winter; accumulates body fat.

Olympic marmots feed on the most common flora of the Olympic National Park high meadows, and their generalized feeding habits keep populations of dominant flora species in the meadows at ecologically healthy levels. The result is an overall increase in species richness in the immediate area. Olympic marmots also act as hosts to fleas (Oropsylla eatoni and Oropsylla spenceri spenceri) as well as certain cestodes (tapeworms) such as Diandrya composita.

Commensal/Parasitic Species:

• Oropsylla eatoni
• Oropsylla spenceri spenceri
• Diandrya composita

Olympic marmots are often preyed upon by large terrestrial mammals and may also be prayed upon by avian raptors. Primary predators include cougars and coyotes. Black bears, golden eagles, and bobcats have also been observed preying on the Olympic Marmot. When a large predator is spotted in the area, members of the colony produce alarm calls.

Known Predators:

• cougar (Puma concolor)
• coyote (Canis latrans)
• golden eagle (Aquila chrysaetos)
• bobcat (Lynx rufus)
• black bear (Ursus americanus)

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 1 - 20

Comments: This species is represented by a small number of occurrences or subpopulations, all within one regional mountain range. The specific number of occurrences depends on how each metapopulation is defined.

1000 - 10,000 individuals

Comments: Barash (1989) believed that the total population size was fewer than 2,000, but more recent estimates put the total at 2,000-4,000. This reflects better information rather than a population increase.

Olympic marmots communicate through physical interaction, vocal, and olfactory methods. Physical social and mating greetings are described in previous sections. They also use chemical markers excreted from a gland in the cheek to mark territory. These marks are most often made on rocks or shrubs. Type and length of vocal calls vary with different external stimuli; vocal responses to an unfamiliar noise or smell differs from vocal responses to the presence of a predator. Calls of an ascending pitch, which have been interpreted as distress calls, include a "chip" or "yell" lasting approximately half a second. Length of calls is negatively correlated with level of distress: calls are shorter when the treat is immediate or realized. Play fighting is characterized by teeth chattering as well as low growls and high pitched "yips."

Communication Channels: tactile ; acoustic ; chemical

Perception Channels: visual ; acoustic

Comments: Probably similar to M. CALIGATA which hibernates for about 8 months each year.

Olympic marmots generally live between 2 and 6 years in the wild. Females that reproduced during the summer have a higher mortality than those that do not. This is attributed to their parental investment; these females spend more time foraging for their young than for themselves. As a result, they can either spend time later in the summer building up their fat supply for winter or hibernate with a lower body mass. By foraging later in the year, females risk mortality through exposure to winter elements. By hibernating with a lower body mass, they risk starvation.

Typical lifespan
Status: wild: 2 to 6 years.

Copulation of Olympic marmots begins immediately following emergence from hibernation. Attempts are initiated by both sexually mature males and females in a number of different ways. Greetings often begin with a sniff of the nasal or genital area, and nasal-nasal or nasal-genital contact commonly occurs. If the female is parous (having already produced a litter), most attempts to mount will be successful and the pair will copulate. Successful mountings of parous females peaks in frequency at 11 to 20 days after emerging from hibernation. Non-parous females (those who have not yet had offspring) show more aggressive behavior and may chase or initiate fights with approaching males. Olympic marmots are polygynous.

Mating System: polygynous

In Olympic marmots, estrus (physiological changes that signal reproductive availability) occurs about two weeks after adults emerge from hibernation. Emergence occurs during early to mid-May. After a gestation period of 4 weeks, females give birth to a litter of 3 to 5 offspring. Juveniles weigh between 1.2 and 1.6 kg at birth (average 1.55 kg). They are weaned around 10 weeks of age and reach independence around 2 years of age. Olympic marmots reach sexual maturity between 2 and 4 years of age.

Sexually mature female Olympic marmots breed every other reproductive season. Reasons for the skipping of a reproductive season are uncertain. A dominant theory suggests that, due to the short period of time between the end of lactation and beginning of hibernation (6 to 8 weeks), adult females weigh less than males and sexually immature females when entering hibernation. This lower ratio of mass to fat can result in mortality during the 8-month hibernation period. Because they are unable to amass enough fat to reproduce each year, they skip reproductive seasons. Another theory contributes reproductive skipping to female aggression establishing dominance. In one study, among colonies of alpine marmots, aggression of mature females caused stress and hormonal changes in subdominant females, preventing them from successfully reproducing.

Breeding interval: Olympic marmots usually breed every other year.

Range number of offspring: 3 to 5.

Average gestation period: 4 weeks.

Range birth mass: 1.2 to 1.6 kg.

Average birth mass: 1.55 kg.

Average weaning age: 10 weeks.

Average time to independence: 2 years.

Range age at sexual or reproductive maturity (female): 2 to 4 years.

Range age at sexual or reproductive maturity (male): 2 to 4 years.

Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Mother Olympic marmots provide considerable care to their young until they reach independence. Infants do not emerge from the burrow until 1 month after birth. The mother spends most of her time near the burrow and leaves only for short periods of time, at most 30 minutes, to forage. Once the infants emerge, the mother stays within yards of her offspring, and she doe not let them venture farm from the burrow. Within several weeks, offspring have become sufficiently independent to forage for themselves.

Parental Investment: female parental care ; pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

Probably similar to M. CALIGATA which mates in spring soon after emergence from hibernation, bears young in late May or early June, produces 1 litter of 4-5 young/year. Young reach sexual maturity probably in 2-3 years (Banfield 1974).

United States

Rounded National Status Rank: N2 - Imperiled

Rounded Global Status Rank: G2 - Imperiled

Reasons: Small range in the Olympic Mountains of northwestern Washington; localized declines and extirpations have occurred since the late 1980s, while other populations have remained stable; coyote predation and tree encroachment into meadows may be responsible for the declines.

Year Assessed

Assessor/s

Reviewer/s

Justification

History

• 1996
  Lower Risk/least concern

Olympic marmots are considered a speices of least concern by the ICUN. Although populations are decreasing and they have a limited geographic range, they are protected by laws that protect the Olympic National Park.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

Population

Population Trend

Global Short Term Trend: Relatively stable to decline of 30%

Comments: Sharp declines and local extirpations have occurred at several colony sites since the late 1980s, although other colonies appear to be stable (Edelman 2003). The overall trend is not known.

Global Long Term Trend: Relatively stable to decline of 50%

Degree of Threat: Medium

Comments: Predation by coyotes and tree encroachment into subalpine meadows may be responsible for recent local declines (S. C. Griffin, pers. comm., cited by Edelman 2003). The latter factor suggests that fire supression might be a potential threat.

Olympic marmots acclimate quickly to human intrusion into colonies and allow observation of behavior (Edelman 2003).

Major Threats

Conservation Actions

Biological Research Needs: Research on population trends and metapopulation dynamics is needed.

Global Protection: Few (1-3) occurrences appropriately protected and managed

Comments: Most of the habitat is protected in Olympic National Park.

There are no known adverse affects of Olympic marmots on humans.

There are no known direct positive effects of Olympic marmots on humans. Because they feed on a variety of flora and are consumed by a variety of predators, they help maintain a thriving ecosystem in the meadows of the Olympic National Park.