Marmota broweriAlaska marmot

Ge­o­graphic Range

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. (Hall and Gilmore, 1934; Slough and Jung, 2007)

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). (Bee and Hall, 1956; Wil­son and Ruff, 1999)

  • Range elevation
    990.6 to 1219.2 m
    3250.00 to 4000.00 ft
  • Average elevation
    1127.76 m
    3700.00 ft

Phys­i­cal De­scrip­tion

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). (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). (Bee and Hall, 1956; Hub­bart, 2011)

  • Sexual Dimorphism
  • male larger
  • Range mass
    2.5 to 4 kg
    5.51 to 8.81 lb
  • Average mass
    3.41 kg
    7.51 lb
  • Range length
    539 to 652 mm
    21.22 to 25.67 in
  • Average length
    592 mm
    23.31 in

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). (Barash, 1989)

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. (Hub­bart, 2011)

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). (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

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). (Hub­bart, 2011)

Lifes­pan/Longevity

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). (Hub­bart, 2011)

  • Typical lifespan
    Status: wild
    13 to 15 years

Be­hav­ior

Alaska mar­mots are so­cial and live in colonies of up to fifty in­di­vid­u­als. How­ever, each mar­mot has its own den (Hub­bart, 2011). The lo­ca­tion of dens and bur­rows in boul­der fields is cho­sen in an at­tempt to ex­clude large preda­tors, such as griz­zly bears, which are not able to reach the an­i­mals be­tween the rock crevices (Bee and Hall, 1956). It has been sug­gested that sum­mer bur­rows are at a lower el­e­va­tion than win­ter bur­rows; how­ever, there is not much ev­i­dence to sup­port this hy­poth­e­sis (Wil­son and Ruff, 1999). (Bee and Hall, 1956; Hub­bart, 2011; Wil­son and Ruff, 1999)

Time spent out­side of the den is usu­ally de­voted to one of two ac­tiv­i­ties: for­ag­ing or look­out duty. All adult in­di­vid­u­als in a colony spend time on look­out duty, dur­ing which they stand on ob­ser­va­tion points around the dens look­ing for preda­tors. This al­lows the other in­di­vid­u­als in the colony to for­age rel­a­tively safely. When a preda­tor is spot­ted, the mar­mot on look­out duty will give an alarm call, which causes the colony mem­bers to re­treat back into their dens. There is ev­i­dence that alarm calls vary slightly de­pend­ing on the type of preda­tor spot­ted. In­di­vid­u­als out­side of their dens who are not on look­out duty or for­ag­ing are usu­ally ei­ther sun­bathing or groom­ing them­selves (Hub­bart, 2011). (Hub­bart, 2011)

The be­hav­ior of Alaska mar­mots is strongly in­flu­enced by mos­qui­toes. Dur­ing the sum­mer months in Alaska, mos­qui­toes can be ex­tremely abun­dant. This causes in­di­vid­u­als to re­main in­side their den on warm, sunny days when the mos­qui­toes are out in vast num­bers. Alaska mar­mots are most ac­tive on cool, cloudy, windy days when the mos­qui­toes are not ac­tive (Hub­bart, 2011; Wil­son and Ruff, 1999). (Hub­bart, 2011; Wil­son and Ruff, 1999)

Mat­ing be­hav­iors of Alaska mar­mots are stim­u­lated by pheromones re­leased by anal scent glands in males and fe­males (Hub­bart, 2011). (Hub­bart, 2011)

Alaska mar­mots hi­ber­nate for the ma­jor­ity of the year. Hi­ber­na­tion be­gins around the first major snow storms in late Au­gust and early Sep­tem­ber and con­tin­ues until the snow be­gins to melt and food be­comes avail­able in early June (Hub­bart, 2011; Wil­son and Ruff, 1999). When hi­ber­na­tion be­gins, Alaska mar­mots block den en­trances with veg­e­ta­tion, stones, soil, and feces. In­di­vid­u­als will hud­dle in groups dur­ing hi­ber­na­tion. Dur­ing this time, heart and res­pi­ra­tory rates de­crease and body tem­per­a­ture de­creases to a tem­per­a­ture be­tween 4.5 and 7.5 de­grees Cel­sius. Hi­ber­na­tion in Alaska mar­mots is dis­con­tin­u­ous. In­di­vid­u­als awaken every three to four weeks to uri­nate and defe­cate, after which hi­ber­na­tion is re­sumed (Hub­bart, 2011). (Hub­bart, 2011; Wil­son and Ruff, 1999)

Home Range

There is no in­for­ma­tion avail­able on the home range or ter­ri­tory size of Alaska mar­mots. How­ever, ter­ri­tory size of the closely re­lated yel­low-bel­lied mar­mot is 0.67 hectares (Ar­mitage, 1974). (Ar­mitage, 1974)

Com­mu­ni­ca­tion and Per­cep­tion

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). (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). (Bee and Hall, 1956)

Food Habits

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). (Hub­bart, 2011; Wil­son and Ruff, 1999)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit
  • flowers

Pre­da­tion

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). (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). (Bee and Hall, 1956; Hub­bart, 2011; Wil­son and Ruff, 1999)

  • Anti-predator Adaptations
  • cryptic

Ecosys­tem Roles

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). (Hub­bart, 2011; Rausch and Rausch, 1971)

Com­men­sal/Par­a­sitic Species
  • fleas (Orop­sylla silantiewi)
  • ces­tode (Cateno­tae­nia reg­giae)
  • ces­tode (Diandrya com­posita)
  • ne­ma­tode (As­caris lae­vis)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

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). (Bee and Hall, 1956; Hub­bart, 2011)

  • Positive Impacts
  • food
  • body parts are source of valuable material

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

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

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). (Wil­son and Ruff, 1999)

Con­trib­u­tors

An­drea Laz­zari (au­thor), Michi­gan State Uni­ver­sity, Bar­bara Lun­dri­gan (ed­i­tor), Michi­gan State Uni­ver­sity, Laura Podzikowski (ed­i­tor), Spe­cial Pro­jects.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal
  1. active during the day, 2. lasting for one day.
endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

omnivore

an animal that mainly eats all kinds of things, including plants and animals

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

polygynous

having more than one female as a mate at one time

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

soil aeration

digs and breaks up soil so air and water can get in

tactile

uses touch to communicate

terrestrial

Living on the ground.

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

Ref­er­ences

Ar­mitage, K. 1974. Male be­hav­iour and ter­ri­to­ri­al­ity in the Yel­low-bel­lied mar­mot. Jour­nal of Zo­ol­ogy, 172: 233-265.

Barash, D. 1989. Mar­mots: So­cial Be­hav­ior and Ecol­ogy. Cal­i­for­nia: Stan­ford Uni­ver­sity Press.

Bee, J., E. Hall. 1956. Mam­mals of North­ern Alaska. Lawrence, Kansas: Uni­ver­sity of Kansas.

Ben­ton, E. 2011. "Mar­mota olym­pus" (On-line). An­i­mal Di­ver­sity Web. Ac­cessed March 07, 2012 at http://​animaldiversity.​ummz.​umich.​edu/​site/​accounts/​information/​Marmota_​broweri.​html.

Hall, E., R. Gilmore. 1934. Mar­mota cali­gata brow­eri, a new mar­mot from north­ern Alaska. The Cana­dian Field-Nat­u­ral­ist, 48: 57-60.

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.

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.

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.

Wil­son, D., S. Ruff. 1999. The Smith­son­ian Book of North Amer­i­can Mam­mals. Wash­ing­ton: Smith­son­ian In­sti­tu­tion Press.