Mammal Species of the World
- Original description: Hall and Gilmore, 1934. Canadian Field Naturalist, 48:57.
occurs (regularly, as a native taxon) in multiple nations
Regularity: Regularly occurring
Type of Residency: Year-round
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).
Alaska marmots are found in the Neartic region of the world. This species has an isolated range in the Brooks Mountains of northern Alaska. Marmota broweri has a patchy distribution because suitable habitat is widely scattered within its range. (Wilson and Ruff, 1999)
Biogeographic Regions: nearctic (Native )
M. broweri is a typical marmot, with coarse hair over a heavy body. The neck is short, the tail is bushy, the legs and feet are powerful, and the claws are strong and well suited to digging. They have typical rodent incisors that are sharp and chisel-like and grow indefinitely throughout life. The thumbs of the front limbs have a flat nail, whereas the other digits have claws.
Adult Alaska marmots have solid black fur on the dorsal surface of the head and the nose. The rest of the pelage is generally dark, blending perfectly with the dark lichens on the rock fields of its local environment.
Body size fluctuates during the year because of hibernation. A marmot leaves its winter sleep very thin but quickly gains weight, with 20% of its body weight being fat stored for its long hibernation at the end of summer. M. broweri displays slight sexual dimorphism. The average total length of adult males being 605 mm and the average weight being 3.63 kg. In comparison, adult females have an average total length of 579 mm and average weight of 3.18 kg. (Wilson and Ruff, 1999)
Range mass: 2.5 to 4.0 kg.
Average mass: 3.4 kg.
Range length: 539 to 652 mm.
Average length: 592 mm.
Other Physical Features: endothermic ; bilateral symmetry
Length: 60 cm
Weight: 3600 grams
Size in North America
Average: 605 mm males; 579 mm females
Range: 582-652 mm males; 539-599 mm females
Average: 3.6 kg males; 3.2 kg females
Range: 3-4 kg males; 2.5-3.5 kg females
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.
Habitat and Ecology
Within the Brooks Mountain range, Alaska marmots occupy boulder fields, rock slides, and rock outcroppings. Marmota broweri uses subsurface space provided by the rocks and boulders to create its living space by burrowing into the permafrost soil. Tundra vegetation surrounds the rocks where M. broweri makes its home. Usually, each den has an observation post, such as a tall rock or cliff edge, within ten meters of its entrance. A marmot will perch on this lookout and keep an eye out for predators. (Wilson and Ruff, 1999)
Range elevation: 991 to 1219 m.
Average elevation: 1128 m.
Habitat Regions: polar
Terrestrial Biomes: tundra ; mountains
- Wilson, D., S. Ruff. 1999. The Smithsonian Book of North American Mammals. Washington, D.C.: The Smithsonian Institute.
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.
Comments: Eats grasses and other green plants.
The tundra vegetation that grows on the sides of mountains is the primary source of nutrition available to M. broweri. In the early mornings and late afternoons, Alaska marmots can be seen grazing in the areas immediately surrounding their dens. The grasses, forbs, fruits, grains, legumes, and the occasional insect that marmots eat are all relatively low in nutritional value. These animals must therefore consume large quantities in order to put on weight for hibernation. Near the end of summer, the contents of am Alaska marmot’s digestive tract account for a fourth to a third of the animal’s total weight. (Nowak, 1983)
Animal Foods: insects
Plant Foods: leaves; seeds, grains, and nuts; fruit
Primary Diet: herbivore (Folivore , Frugivore , Granivore )
The mini-ecosystem to which M. broweri belongs would be the rock pile. Voles scurry in-between the rocks, wolverines range along the outside of the rocks, and caribou graze over the rocks. The marmot helps to enrich the soil with its uneaten food, nesting material, fecal pellets, and excavated soil. (Nowak, 1983) It is also likely that the population of marmots affects populations of predators in proportion to the importance of marmots in the predators’ diets.
Ecosystem Impact: soil aeration
Marmots post sentries to look out for predators. Common predators of Alaska marmots are wolverines, wolves, grizzly bears, and eagles. At the sight of a predator, the sentry shrieks an alarm and all members of the family or colony retreat into their dens. Grizzly bears are able to dig marmots right out of their dens, so building dens under large boulders is important to Alaska marmots. Eagles are the principal predators of juveniles. (Wilson and Ruff, 1999)
This list may not be complete but is based on published studies.
Known prey organisms
Life History and Behavior
Comments: Hibernates in winter.
Life span is not known, but it is believed to be similar to that of the related species, M. marmota, which is thirteen to fifteen years. (Nowak, 1983)
Status: wild: 13 to 15 years.
Litter of 4-5 is born late spring to early summer.
A male may have one or more females living on his territory. He mates with those females.
Mating System: monogamous ; polygynous
Alaska marmots mate once per year, usually in early spring. The litter size is between three and eight young, with an average of four or five. Sexual activity is stimulated by odors from the anal scent glands of both sexes. Prior to giving birth, the female closes off the den. She gives birth alone. Both sexes are involved in raising and protecting the young. (MacDonald, 1999)
Alaska marmots have a gestation period of roughly five weeks. Pups are born naked, toothless, and helpless with their eyes closed (MacDonald, 1999). Around six weeks of age, the young have dense, soft fur, and are independent enough to explore outside the den. Young marmots go through three pelages in their first year, with the final pelage resembling the adult (Wilson, 1999). Alaska marmots are fully-grown after two years (MacDonald, 1999). The young play outside while the old stand guard. Offspring hibernate and live with their parents for two years
Breeding season: Animals breed in the early spring, and give birth about six weeks later.
Range number of offspring: 3 to 8.
Average number of offspring: 4.
Average gestation period: 6 weeks.
Range age at sexual or reproductive maturity (female): 2 to 3 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); viviparous
Females care for the young in a natal burrow, and then males may help with the care of the offspring. The young are naked and helpless at birth,
Parental Investment: altricial ; male parental care ; female parental care
National NatureServe Conservation Status
Rounded National Status Rank: N4 - Apparently Secure
NatureServe Conservation Status
Rounded Global Status Rank: G4 - Apparently Secure
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Lower Risk/least concern(Baillie and Groombridge 1996)
M. broweri is widely spread throughout the Brooks Range but its population densities are usually low. Alaska marmots may be hunted by natives, but not to the point of endangerment. The marmot population is stable within its range. (Wilson and Ruff, 1999)
CITES: no special status
IUCN Red List of Threatened Species: least concern
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
No negative effects of this species on humans have been reported.
Economic Importance for Humans: Positive
Historically, M. broweri were occasionally hunted by the native people of Alaska for meat. More often, marmots were harvested for their thick fur. An Eskimo hunter would spend all summer hunting marmots to make a parka, as it takes about twenty marmot skins to make one parka. The marmots can be shot, but were often caught in rock fall traps. (Bee, 1956)
Positive Impacts: food
The Alaska marmot (Marmota broweri), also known as the Brooks Range marmot or the Browers, is a species of rodent in the family Sciuridae. It is found in the scree slopes of the Brooks Range, Alaska. They eat grass, flowering plants, berries, roots, moss, and lichen. These marmots range from about 54 cm to 65 cm in length and 2.5 kg to 4 kg in weight. Alaska celebrates every February 2 as "Marmot Day," a holiday intended to observe the prevalence of marmots in that state and take the place of Groundhog Day.
- 1 Etymology
- 2 History
- 3 Status
- 4 Physical Description
- 5 Ecology
- 6 Behavior
- 7 Evolution and Fossils
- 8 References
Originally Marmota broweri was perceived as a synonym for M. caligata, but this was soon proven false when evidence was found that corroborated M. broweri as a unique species. Cytochrome b sequences were used to verify that M. broweri as its own distinct species.
Marmota broweri are sometimes hunted by Alaskan Natives for food and their warm fur. An Eskimo hunter would spend all summer hunting marmots to make a parka, as it takes about 20 marmot pelts to make a single parka.
Marmot Day is essentially Alaska's version of Groundhog Day. Sarah Palin signed a bill in 2009 to officially make every February 2nd Marmot Day. The bill, introduced by Senator Linda Menard, said, "It made sense for the marmot to become Alaska's version of Punxsutawney Phil, the Pennsylvania groundhog famed for his winter weather forecasts." She did not expect marmots to have any weather forecasting duties but rather hoped that the state would create educational activities regarding the marmot.
The status of Alaska marmots is not well known due to the difficulties in finding them in their natural habitats. According to IUCN: Red List of Threatened Species ver. 3.1, the Alaska marmot is considered to be a “Least Concern” status signifying a relatively low concern in terms of the dangers they face. Although Alaska marmots may be hunted, their population is stable and not at risk for endangerment. In fact, the Alaska marmot has been declared the least threatened species of marmot.
Alaskan marmots are mammals. They possess a short neck, broad and short head, bushy tail, small ears, short powerful legs and feet, densely furred tail, and a thick body covered in coarse hair. Adult Alaska marmots’ fur on their nose and the dorsal part of their head are usually of a dark color. Their feet may be light or dark in color. M. broweri have tough claws adapted for digging, however the thumbs of their front limbs do not have these claws but flat nails instead. Their body size is highly variable due to hibernation cycles. For males, the average total length is 61 cm and the average weight is 3.6 kg. Adult females are slightly smaller, having an average length of 58 cm and 3.2 kg.
The retina of the eye of Alaska marmots is entirely lacking of rods, making their night vision quite poor. They also lack the fovea of the eye, making their visual acuity much worse than other rodents. The location of their eyes makes their field of vision very wide, sideways and upward. All of their teeth will grow throughout their lifetime, resembling sharp rodent incisors. There is a single pair of incisors in each jaw.
Location and distribution
In terms of global distribution, the Alaska marmot is nearctic. Current distribution of the Alaska marmot include the Brooks Range, Ray Mountains, and Kokrines Hills. They exist in the mountains that lie north of the Yukon and Porcupine rivers in central and northern Alaska. However, there have been reports of Alaska marmots in the Richardson Mountains in the northern Yukon Territory but these sightings have not yet been confirmed.
Alaska marmots are found scattered throughout Alaska as small colonies each consisting of various families. Their locations have been documented in the Brooks Range from Lake Peters to Cape Lisburne and Cape Sabine that lies westward. There have been sightings of marmots near rivers in the Northern Baird mountains and in the Mulik Hills. They have also been sighted near copter Peak in the DeLong Mountains. Species have also been secured south of the Brooks Range in the Spooky Valley and in the Kokrines Hills.
The Alaska marmots live in polar habitats including the terrestrial tundra and mountain biomes. They are located at elevations of about 1000 m to 1250 m. They are often found in boulder fields, rock slides and outcrops, terminal moraines, and Talus slopes  in Alpine tundra with herbaceous forage. They are often found on mountain slopes surrounding lakes, and are found less commonly away from a lake. To create their shelter Alaska marmots burrow into permafrost soil containing tundra vegetation, and within ten meters a rocky ledge serves as an observation post. Alaska marmots live in relatively permanent winter dens that serve as a marmot colonies’ shelter for at least twenty years. A colony is essentially several individual family burrows built in close proximity to one another. Their dark fur serves as a mild camouflage in their rocky environments. Wind is also very important to an Alaska marmot's habitat and climate because it removes annoying mosquitoes. If there are large amounts of mosquitoes in the area due to a lack of wind, marmots will actually remain in their dens until the climate changes and the number of mosquitoes decrease.
Tundra vegetation that grows on mountain sides are the primary nutrition source and they include; grasses, forbs, fruits, grains, legumes, and occasionally insects. M. bromeri must eat large amounts of the arctic plants because they are low in nutritional value and for preparation of hibernation. Alaska marmots are typically known as omnivores but they have also been described as insectivorous, folivorous, frugivorous, and granivorous.
Although dangers of direct human disturbance are minimal, climate dangers pose a real problem. The Alaska marmot is arguably the most sensitive of the 14 Marmot species to anthropogenic disturbances, including climate change.
Marmots enrich soil with uneaten food, nesting material, by their feces, and help to aerate the soil by their excessive digging. They also serve as a minor food source for a variety of predators.
Alaska marmots are very social, living in colonies of up to 50 while all sharing a common burrow system. Marmots typically have their own personal den, while the young live with their mother and the father lives in a nearby den. Especially in large colonies, the Alaska marmots utilize sentry duty rolls that are periodically rotated. A sentry marmot will alert the colony via a two-toned, high-pitched warning call (marmot vocalizations) if there is a predator in the area. The older marmots will defend and keep a lookout for predators while the young play. Solely dirt dug dens provides limited protection, but a den built under rocks and boulders can prevent the risk from large animals, such as Grizzly bears, who can dig marmots out of their dirt dug dens.
M. broweri will mark their territory by secreting a substance from face-glands and rubbing the sides of their face on rocks around their den and various trails. Alaska marmots also enjoy sunbathing and spending a large amount of time in personal grooming.
M. broweri is one of the longer hibernating marmots, being documented to do so up to eight months annually. Alaska marmots accumulate a thick fat layer by late summer to sustain them throughout the winter hibernation. Alaska marmots are active until snow begins to fall, in which they will go to their hibernacula from around September until June. Alaska marmots have special winter dens with a single entrance that is plugged with a mixture of dirt, vegetation, and feces during the entire winter hibernation period. They are built on exposed ridges that thaw earlier than other areas, and the entire colony stays within the den from September until the plug melts in early May. They then resettle in their dens in family units to communally hibernate for the winter. Communal hibernation may be an adapted strategy to reduce metabolic cost while trying to keep their body temperatures above freezing. In order to seal their hibernaculum off from the elements, they will plug their entrance with hay, earth, and stone. During hibernation many of their body functions decrease; body temperature (averages between 4.5 and 7.5 degrees Celsius), heart rates, respiratory rates, and metabolic rates. Alaska marmot hibernation is not continuous because they will awaken every three or four weeks in order to urinate and defecate. Inside the hibernaculum den, the Alaska marmot has shown long-term hibernation adaptions by their ability to tolerate high CO2 levels and low O2 levels. As an adaption to the Arctic environment and permanently frozen ground, Alaska marmots breed prior to emerging from the winter den. The Alaska marmots will generally emerge from the den during the first 2 weeks of May.
Male Alaska marmots are polygynous, mating with the monogamous females living on their territory. They are seasonal iteroparous and viviparous breeders that mate once per in the early spring and give birth about six week later with litter sizes ranging from 3 to 8 and an average litter size of 4-5. The male and female Alaska marmots are involved in both raising and protecting the pups in their natal burrow. In both sexes sexual reproductive behaviors are stimulated by odors released from anal scent glands. Before birthing, the female will first close her den off and then she will give birth alone. The Gestation period is about 5–6 weeks. Newly born Alaskan marmots are altricial; hairless, toothless, blind  and are quite vulnerable to predators. After about six weeks young marmots have thick, soft fur and they begin to temporarily leave the den. They will go through 3 coats in their first year until their final one, which resembles adult Alaska marmots. They will hibernate and live with their parents at least one year, they will be fully-grown after two years and reach sexual maturity from 2 to 3 years. Marmots life span are not known but it is believed to be about 13–15 years.
M. broweri has been reported to have been successfully reared in captivity and reintroduced into the wild (however there have been cases where captive rearing led to high rates of mortality).
Evolution and Fossils
The Alaska marmot has ancestry to the Pleistocene epoch. There have been no known fossils of Marmota broweri. However, the M. flavescens fossil recovered from the Late Pleistocene age from the Trail creeks caves on the Seward Peninsula  is speculated to be an incorrect identification of the fossil  This fossil could be M. broweri.
The evolutionary lineages of the 14 marmot species distributed across the Holarctic are relatively ambiguous. Cytochrome b sequences indicated that M. broweri is most likely related to M. caudata, cenzbieri, marmota, and monax. In support to the cytochrome b results, experimentation involving mitochondrial DNA has suggested that M. broweri is most likely related to M. caudata and M. menzbieri. However, morphological data have linked M. broweri to M. camtschatica. In addition, somatic chromosome analysis of marmots, ecological data and behavioral data have shown that there is a link between M. broweri and M. caligata. The conflicting data pertaining to phylogeny creates inconsistent marmot lineage relationship hypotheses.
|Wikimedia Commons has media related to Marmota broweri.|
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Names and 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.