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Overview

Brief Summary

Description

The Alaska Marmot lives in the Brooks Range, in northern Alaska, squeezing between big, bulky rocks on slopes to dig its dens. Denning on rocky ledges or under boulders offers them some protection from grizzly bears, which would otherwise dig them out. Wolverines and wolves also prey on Alaska Marmots, and eagles prey on young marmots. If an eagle is circling overhead or a predator is nearby, the marmots give warning calls and scurry to safety underground. In their harsh environment, the soil is permanently frozen. The marmots live in small population clusters close to productive plant-foraging areas. The nutritional quality of Arctic plants is low and the animals must consume a great deal to meet their requirements—and to prepare for hibernation. These marmots disappear underground with the first snowstorms, in September, and hibernate until June.

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Mammal Species of the World
  • Original description: Hall and Gilmore, 1934.  Canadian Field Naturalist, 48:57.
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Distribution

Alaska marmots (Marmota broweri) can only be found in the Nearctic region of the world. Hall and Gilmore (1934) reported that they have a very limited range in Northern Alaska, along the Arctic coast. Later work done by Slough and Jung (2007) suggests that the range of the Alaska marmot should include only the Brooks Range mountains in northern Alaska. They speculate that Alaska marmots might also occur in the Yukon, but there is currently no evidence to support this claim.

Biogeographic Regions: nearctic (Introduced )

  • Hall, E., R. Gilmore. 1934. Marmota caligata broweri, a new marmot from northern Alaska. The Canadian Field-Naturalist, 48: 57-60.
  • Slough, B., T. Jung. 2007. Diversity and Distribution of the Terrestrial Mammals of the Yukon Territory: A Review. The Canadian Field-Naturalist, 121: 119-127.
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Range Description

This species is known from the Brooks Range of northern Alaska in the United States, from near the coast of Chukchi Sea to the Alaska-Yukon border; perhaps also northern Yukon in Canada (Hoffmann et al., in Wilson and Reeder 1993).
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occurs (regularly, as a native taxon) in multiple nations

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National Distribution

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

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Global Range: Brooks Range of northern Alaska from near coast of Chukchi Sea to Alaska-Yukon border; perhaps also northern Yukon (Hoffmann et al., in Wilson and Reeder 1993).

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Physical Description

Morphology

Alaska marmots are distinguished from other species of marmots by the black fur on top of their head, extending from the tip of the nose to the neck. These marmots have coarse hair that ranges in color from brown and black to white. Their back usually has brown hair, with a lighter brown underneath the black-tipped guard hairs. Their dark fur provides useful camouflage against the foliage and boulder fields in their habitat. Alaska marmots are fairly large (males are slightly larger than females) and heavy-bodied, with a short neck and a slightly flattened, bushy tail. The tail usually accounts for a third to a fifth of the total body length. Alaska marmots have black lips and black feet. The front feet sometimes have white markings. They have no fur on their palms (which have five pads) or their soles (which have six pads). Each limb has five digits with claws. The claws of the forelimbs are thick and curved for digging. The thumbs of the forelimbs have a flattened nail instead of a claw. Their legs are short, thick, and muscular. Alaska marmots have five pairs of mammae, for a total of ten. The eyes are small and circular and the furry ears are broad, short, and rounded. Alaska marmots have cheek pouches, but they are vestigial. Due to hibernation, weight varies across seasons, but they are able to gain weight quickly after emerging from hibernation. Alaska marmots experience one molt during the summer, but it does not seem to have a uniform pattern (Bee and Hall, 1956; Hubbart, 2011; Wilson and Ruff, 1999).

Alaska marmots are rodents, and so have the typical, chisel-like ever-growing incisors (Hubbart, 2011). Based on figures in Bee and Hall (1956), the cheekteeth of Alaska marmots have high ridges that fan out. Hubbart (2011) reports the dental formula of I 1/1, C 0/0, P 2/1, M 3/3 = 22. Compared to other species of marmots, Alaska marmots have a larger postorbital width and longer tympanic bullae. These marmots also have a short, deep angular process. The rostrum is fairly long and the postorbital process is wide. The zygomatic arches are complete and quite rounded. The sagittal crest and lambdoidal ridge are both fairly prominent (Hubbart, 2011).

Range mass: 2.5 to 4 kg.

Average mass: 3.41 kg.

Range length: 539 to 652 mm.

Average length: 592 mm.

Sexual Dimorphism: male larger

Other Physical Features: endothermic ; bilateral symmetry

  • Hubbart, J. 2011. Current Understanding of the Alaska Marmot (Marmota broweri): A Sensitive Species in a Changing Environment. Journal of Biology and Life Sciences, 2: 6-13.
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Size

Length: 60 cm

Weight: 3600 grams

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Size in North America

Length:
Average: 605 mm males; 579 mm females
Range: 582-652 mm males; 539-599 mm females

Weight:
Average: 3.6 kg males; 3.2 kg females
Range: 3-4 kg males; 2.5-3.5 kg females
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Ecology

Habitat

Alaska marmots have a scattered distribution, because they prefer a distinct habitat (Wilson and Ruff, 1999). They inhabit boulder fields and rocky outcrops on the slopes and in the valleys and canyons of the Brooks Mountains (Bee and Hall, 1956). They prefer particularly boulder fields and rocky outcrops where there are large enough spaces for them to dig dens between rocks. The entrances to the dens are usually protected by boulders, which helps to shield Alaska marmots from various predators. There are usually one or more observation points on top of the boulders near the den entrance, where Alaska marmots search for predators before beginning to forage (Wilson and Ruff, 1999). It is rare to find Alaska marmots living in boulder fields that are far from productive foraging sites (Bee and Hall, 1956).

Range elevation: 990.6 to 1219.2 m.

Average elevation: 1127.76 m.

Habitat Regions: polar ; terrestrial

Terrestrial Biomes: tundra ; mountains

  • Bee, J., E. Hall. 1956. Mammals of Northern Alaska. Lawrence, Kansas: University of Kansas.
  • Wilson, D., S. Ruff. 1999. The Smithsonian Book of North American Mammals. Washington: Smithsonian Institution Press.
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Habitat and Ecology

Habitat and Ecology
It occurs in arctic tundra, where there are extensive boulder fields, rock-slides, rock outcroppings, or talus. Requires secure den sites for protection against predation by grizzly bears. Young are born in underground burrows. A litter of 4-5 is born late spring to early summer. It eats grasses and other green plants, and hibernates in winter.

Systems
  • Terrestrial
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Comments: Dens located in extensive boulder fields or in talus slopes with large rocks adjacent to productive tundra (Wilson and Ruff 1999). Young are born in underground burrows.

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Migration

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.

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Trophic Strategy

Alaska marmots are primarily herbvivorous, eating mostly the tundra vegetation growing near their burrows. They can also be classified as folivorous, granivorous, frugivorous, insectivorous, and omnivorous, due to the grasses, forbs, grains, legumes, fruits, and few insects in their diet, respectively. Due to the low nutritional quality of their food, Alaska marmots must spend a great deal of time foraging and eat a large quantity of food. This is why they often create dens and burrows very near their food sources. By the end of the summer, it is not uncommon for the contents of the stomach and digestive tract of Alaska marmots to account for up to one third of its total body weight. Alaska marmots compete indirectly with animals such as Dall's sheep, caribou, and other small rodents for food (Hubbart, 2011; Wilson and Ruff, 1999).

Animal Foods: insects

Plant Foods: leaves; seeds, grains, and nuts; fruit; flowers

Primary Diet: carnivore (Insectivore ); herbivore (Folivore , Frugivore , Granivore ); omnivore

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Comments: Eats grasses and other green plants.

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Associations

Alaska marmots are an important prey species for many animals, including grizzly bears, wolves, wolverines, and eagles Accipitridae (Hubbart, 2011). Alaska marmots are also a host species for a variety of parasites, including species of fleas, nematodes, and cestodes (Rausch and Rausch, 1971; Hubbart, 2011). Alaska marmots play an important role in soil enrichment and aeration. Digging dens and burrows helps to aerate the soil, while uneaten food, nesting material, and fecal matter help enrich it (Hubbart, 2011).

Ecosystem Impact: soil aeration

Commensal/Parasitic Species:

  • Rausch, R., V. Rausch. 1971. The Somatic Chromosomes of Some North American Marmots (Sciuridae), with Remarks on the Relationships of Marmota browerii Hall and Gilmore. Mammalia, 35: 85-101.
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Alaska marmots are preyed on by a number of species. Eagles, including the golden eagle, frequently prey upon juvenile marmots. Grizzly bears, wolves, and wolverines all pose a threat to juvenile and adult Alaska marmots (Wilson and Ruff, 1999).

Alaska marmots exhibit two anti-predator strategies. Because this is a social species, individuals take turns on lookout duty, communicating to other colony members with alarm calls when they spot a predator nearby. The observation points near den entrances are used by marmots on lookout duty (Bee and Hall, 1956). Observation points are also used by individuals outside of the den to search for predators before beginning to forage (Wilson and Ruff, 1999). The sounding of an alarm call causes group members to retreat back into their dens (Hubbart, 2011). Bee and Hall (1956) claimed that the alarm call of Alaska marmots can vary slightly depending on the type of predator and its location. They also observed that non-predator animals do not cause any kind of call. The fur color of Alaska marmots provide camouflage against the foliage of the mountainsides and boulder fields (Hubbart, 2011).

Known Predators:

Anti-predator Adaptations: cryptic

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Known predators

Marmota broweri is prey of:
Accipitridae
Ursus arctos
Gulo gulo
Canis lupus

This list may not be complete but is based on published studies.
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Known prey organisms

Marmota broweri preys on:
Insecta

This list may not be complete but is based on published studies.
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Life History and Behavior

Behavior

Communication in Alaska marmots, specifically alarm calling, is particularly well studied. This involves both a well-developed sense of hearing and a well-developed sense of sight. All adult Alaska marmots spend time on sentry duty, standing on top of observation points on the lookout for predators. When a predator is spotted, the marmot on sentry duty will emit an alarm call, which alerts the other individuals outside of the dens of the potential danger, causing them to retreat back inside their respective dens. Bee and Hall (1956) described the call as being low pitch and slurred. It is important to note that only predatory animals stimulate alarm calling, and that these calls can vary slightly based on the type of predator. For example, eagles stimulate approximately four consecutive calls, while humans elicit one to two. Predators far away from the colony result in a continuous call, though it seems less urgent (Bee and Hall, 1956).

Alaska marmots do not seem to benefit from the alarm calls of other species. However, it is possible that other species benefit from the alarm calls of Alaska marmots (Bee and Hall, 1956).

Communication Channels: acoustic ; chemical

Other Communication Modes: pheromones

Perception Channels: visual ; tactile ; acoustic ; chemical

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Cyclicity

Comments: Hibernates in winter.

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Life Expectancy

The lifespan of Alaska marmots are unknown. However, it is likely similar to that of related species, which are expected to live between 13 to 15 years. Nothing is known about the captive lifespan of Alaska marmots (Hubbart, 2011).

Typical lifespan

Status: wild:
13 to 15 years.

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Reproduction

Alaska marmots live in family groups, or colonies, consisting of males and females. A male will usually mate with one or more females living in dens near his own (Hubbart, 2011; Wilson and Ruff, 1999). Mating is stimulated by pheromones released from the anal scent glands of both males and females. Copulation usually takes place inside the den before Alaska marmots emerge from hibernation in the spring (Hubbart, 2011). There is no information available on the pre-copulation behavior of Alaska marmots. However, in the closely related Olympic marmots, these behaviors include sniffing, chasing, and fighting. Alaska marmots may exhibit similar behaviors (Barash, 1989).

Mating System: polygynous

Alaska marmots breed once a year around the time that they begin to emerge from hibernation. This is usually early in the month of June. Gestation time is five to six weeks and a female can have a litter of three to eight young, averaging usually four or five. Before giving birth, a female closes off her den so that she can be alone. Her litter is born altricial, but by six weeks old, the young are able to leave the den and explore outside. The timing of weaning of the litter is unknown; however, Hubbart (2011) reports that it may be at six weeks when the young are able to leave the den, as this is the common pattern for other species of marmot.

During their first year of life, juvenile Alaska marmots produce three fur coats, the third being similar to that of adults. Juveniles live and hibernate with their parents for two years, at which time they become independent adults. At three years of age, both males and females become sexually mature (Hubbart, 2011).

Breeding interval: Alaska marmots breed once yearly.

Breeding season: Alaska marmots mate in June, after emerging from dens at the end of hibernation period.

Range number of offspring: 3 to 8.

Average number of offspring: 4.

Range gestation period: 5 to 6 weeks.

Average time to independence: 2 years.

Average age at sexual or reproductive maturity (female): 3 years.

Average age at sexual or reproductive maturity (male): 3 years.

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

Both male and female Alaska marmots raise and protect their litter. This investment lasts for two years, at which time the juveniles become independent of their parents. During those two years, both parents provide shelter and protection year round (Hubbart, 2011).

Parental Investment: altricial ; male parental care ; female parental care

  • Barash, D. 1989. Marmots: Social Behavior and Ecology. California: Stanford University Press.
  • Hubbart, J. 2011. Current Understanding of the Alaska Marmot (Marmota broweri): A Sensitive Species in a Changing Environment. Journal of Biology and Life Sciences, 2: 6-13.
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Litter of 4-5 is born late spring to early summer.

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Conservation

Conservation Status

While they has a limited range and a scattered population distribution, Alaska marmots are not threatened and appear to have a stable population size. Hunting does not seem to have a significant or detrimental affect on the population (Wilson and Ruff, 1999).

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

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IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2008

Assessor/s
Linzey, A.V. & NatureServe (Hammerson, G. & Cannings, S.)

Reviewer/s
Amori, G. (Small Nonvolant Mammal Red List Authority) & Chanson, J. (Global Mammal Assessment Team)

Contributor/s

Justification
Listed as Least Concern because it has a relatively wide range, its populations are secure and there are no major threats.

History
  • 1996
    Lower Risk/least concern
    (Baillie and Groombridge 1996)
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National NatureServe Conservation Status

United States

Rounded National Status Rank: N4 - Apparently Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G4 - Apparently Secure

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Population

Population
This species is apparently secure in its range (NatureServe). It occurs in family groups, with widely scattered populations. Although generally low in density, no estimates are available.

Population Trend
Stable
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Threats

Major Threats
There are no known threats to this species.
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Management

Conservation Actions

Conservation Actions
This species is not of conservation concern and its habitat is not currently under threat.
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Relevance to Humans and Ecosystems

Benefits

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

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Alaska natives have been known to hunt Alaska marmots for meat, and more often, for fur. The most common method used to hunt the animal is with rock fall traps (Hubbart, 2011). It has been reported that the fur of Alaska marmots is fairly valuable, with an average profit of six to eight dollars per pelt (Bee and Hall, 1956).

Positive Impacts: food ; body parts are source of valuable material

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Names and Taxonomy

Taxonomy

Comments: Marmota broweri was regarded as a synonym or subspecies of M. caligata, the hoary marmot of western North America, by Hall and Gilmore (1934) and Hall (1981), but Rausch and Rausch (1965), followed by Hoffmann et al. (1979), provided evidence that broweri is a distinct species. Jones et al. (1992) and Hoffman et al. (in Wilson and Reeder 1993) and Thorington and Hoffmann (in Wilson and Reeder 2005) recognized M. broweri and M. caligata as distinct species.

Hoffmann and Nadler (1968) and others believed this Alaska endemic to be most closely related to the black-capped marmot, M. camtschatica, of northeastern Asia, representing a late Pleistocene migrant to Alaska and subsequent speciation. However, this view was challenged by a molecular (cytochrome b) study (Steppan et al. 1999) that found no close sister species relationship to either M. camtschatica or M. caligata, suggesting that that the ancestry of the Alaska marmot dates back earlier in the Pleistocene, a view also put forward by Rausch and Rausch (1971). These and other studies (e.g., Cardini 2003, Polly 2003, Cardini et al. 2005) have so far failed in their attempts to reject hypotheses of either a Nearctic or Palearctic origin for this enigmatic marmot.

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