Yellow-bellied marmots are distributed widely in the western United States and Canada. They range as far north as southcentral British Columbia and Alberta in Canada and as far south as the Sierra Nevada.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Range includes western North America from south-central British Columbia and southern Alberta southward to southern California, Nevada, southern Utah, and the Sangre de Cristo Mountains in northern New Mexico, typically at elevations above 2,000 meters.

Yellow-bellied marmots are a small to medium-sized rodents. Males weigh from 2.95 to 5.22 kg, with an average of 3.9 kg. Females range in mass from 1.59 to 3.57 kg, with an average of 2.8 kg. Total length ranges from 470 to 700 mm, with tail length ranging from 130 to 220 mm. Hind-foot length from 70 to 90 mm, and condylobasal length ranges from 68.0 to 99.8 mm. Males are longer than females and weigh significantly more. Also, individuals from low, arid-land habitats tend to be smaller than those from mesic, montane habitats. They have robust bodies, with short and broad heads. The head has a narrow interorbital region, with temporal ridges brought joining to form a low, short, sagittal crest. The posterior end of the palate lies obtusely, and the teeth of the upper jaw lie slightly more anterior than the teeth of the bottom jaw. The dental formula is 1/1, 0/0, 2/1, 3/3 = 22. The cheek teeth are high-crowned. Yellow-bellied marmots have small, well-furred ears, feet with five digits and an oval pad in the center of the sole of the hind foot, short and slightly curved claws with a rudimentary nail-bearing thumb, and ten mammae – two pectoral, two abdominal, and one inguinal pair.

The underfur of yellow-bellied marmots is soft, dense, and wooly on the back and sides of the body. Longer, coarse outer guard hairs with lighter tips and darker bases cover the entire body, making the overall color yellow-brown to tawny. Individuals are rarely dark brown and never black, except in melanistic individuals (common in populations in southern Rocky Mountains). There are also noticeable buffy yellowish patches on the side of the neck, white spots between the eyes, and a yellow or orange-russet color covering the belly, with feet a buffy, hazel, or dark brown color. There is great variety in color within subspecies. Yellow-belied marmots molt once annually during summer.

Range mass: 1.59 to 5.22 kg.

Average mass: 3.35 kg.

Range length: 470 to 700 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Average basal metabolic rate: 8.626 W.

Length: 70 cm

Weight: 4500 grams

• Terrestrial

Yellow-bellied marmots generally live in moderately warm, dry habitats at low to mid elevations. They are found in many different habitats, including semi-desert, woodland and forest openings, and the alpine zone. Those that live further south live at higher elevations. For example, in the White Mountains of California they are found only above 2000 m. Moreover, because of absence from valleys, southern populations are isolated from one other, forming isolated populations. In addition, congeners may affect their distribution. It can be inferred that the presence of hoary marmots inhibit the distribution of yellow-bellied marmots in certain high elevation areas, as both occupy subalpine and alpine areas. Yellow-bellied marmots inhabit vegetated fortified slopes or rock outcrops in meadows, which serve as support for the burrows that they reside in, as well as sunning and observation posts. The main entrance of burrow, which they dig themselves, is usually about 0.6 m deep into the ground, and extends about 3.8 to 4.4 m horizontally into the hillside. Many short tunnels branch from main passageway, sometimes connecting to other burrows. Burrows stay relatively stable and thus serve as preferable places to raise young, hibernate, and hide from potential predators. Burrow availability may affect marmot distribution, as well as visibility and safety from predators. Most yellow-bellied marmots occur around 2000 m in elevation.

Average elevation: 2000 m.

Habitat Regions: terrestrial

Terrestrial Biomes: desert or dune ; savanna or grassland ; forest ; mountains

Comments: Yellow-bellied marmots occupy alpine tundra, subalpine and montane meadows, and foothills and canyons at lower elevations. They are semifossorial; individuals use one or more burrows; may share hibernation burrow. Burrows open under rocks (or logs or bushes) in areas of well-drained talus, rock outcrops, or scattered boulders. Habitat sizes range from 0.01 to 70 ha or more (Armitage 1991). 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.

Virtually all males and slightly less than half the females disperse from the natal colony, typically as yearlings and regardless of population density in males; dispersal distance usually is less than 4 km but up to 15.5 km for males and 6.4 km for females in western Colorado (Armitage 1991).

In Colorado, home range size of adult males varied greatly (0.06-47.5 ha, median 1 ha); several males made excursions from their home range (Salsbury and Armitage 1994).

Yellow-bellied marmots are herbivorous, eating a large range of plant types, including grasses, flowers, and forbs. In late summer, large numbers of seeds are eaten. They are most likely not food limited, eating only 0.8 to 3.1% of available net primary production. Food might be limited in areas where snow cover remains into the spring. They are selective feeders and are known to reject parts of plants that are toxic.

Plant Foods: seeds, grains, and nuts; flowers

Primary Diet: herbivore (Folivore , Granivore )

Comments: Generalist herbivore. Feeds on a wide variety of grasses and forbs. Does not store food for the winter.

Interspecific competition with other species, such as hoary marmots may affect the distribution and density of yellow-bellied marmots. As seed predators, yellow-bellied marmots may serve as habitat engineers that contribute to the density and composition of plant communities throughout their geographic range. In addition, yellow-bellied marmots are important prey for a number of different aerial and terrestrial predators. Once abandoned, burrows likely serve as important habitat for other fossorial and semi-fossorial species.

Ecosystem Impact: disperses seeds; creates habitat

Yellow-bellied marmots have a variety of aerial and terrestrial predators. Coyotes are their most important predator, followed by badgers, American martens, black bears, and golden eagles. Risk of predation may influence foraging behavior, social behavior, and habitat selection, as individuals attempt to reduce risk of predation by remaining in borrows for extended periods of time. Predation appears to be only a minor cause of mortality for colonial animals and is more significant among populations residing at habitat margins.

Known Predators:

• coyotes (Canis latrans)
• badgers (Taxidea taxus)
• American martens (Martes americana)
• black bears (Ursus americanus)
• golden eagles (Aguila chrysaetos)

Anti-predator Adaptations: cryptic

Yellow-bellied marmot communication includes auditory and chemical signals. They express alarm, alertness, or threats through whistles. They use their cheek glands to leave scent marks that may help convey social status.

These marmots live alone, in pairs, or colonies. Colonies typically consist of one or more adult territorial males, 1-5 adult females and their young (usually including yearlings and younger offspring). Small habitat patches may include a female and her offspring but adult males and yearlings may not be present (Armitage 1991).

May harbor fleas that are vectors of sylvatic plague or tick that transmits Rocky Mountain spotted fever.

Communication between yellow-bellied marmots is mostly auditory and visual. There are three main vocalizations: the whistle, the undulating scream, and the tooth chatter. Six different whistles are recognized and may have more than one function, such as alerting and threatening. Screams usually respond to excitement or fear, and tooth chattering is used as a threat. Other animals such as American pikas and golden-mantled ground squirrels may respond to marmot alarm calls. Yellow-bellied marmots have cheek and anal glands. Scent marking occurs with cheek glands in conflict situations, having more of a dominance rather than territoriality function.

Communication Channels: visual ; acoustic ; chemical

Other Communication Modes: scent marks

Perception Channels: visual ; acoustic

Comments: At higher elevations these marmots hibernate from early September to May; at lower elevations they may emerge as early as February to mid-March. In the mountains of western Colorado, spring emergence from hibernation begins in late April or early May; immergance for hibernation begins in late August and usually is completed by mid-September (Armitage 1991). In some lower elevation areas, marmots may estivate during dry periods in summer. In more boreal zones, marmots may be active all summer but may begin estivation in June at lower elevations (Frase and Hoffmann 1980).

Activity occurs in daylight. Activity is unimodal with peak activity in early afternoon in spring and fall, bimodal with peaks in morning and late afternoon in summer (Armitage 1991).

Most yellow-bellied marmots live for 13 to 15 years in the wild. Predation, which accounts for 98% of summer mortality significantly limits the average lifespan of this species. A significant number of deaths occur during hibernation and emigration. Recently, sylvatic plague, caused by the bacterium Yersinia pestis, has had a significant impact on populations in California.

Range lifespan

Status: wild: 13 to 15 years.

Yellow-bellied marmots are most often classified as polygynous. They can live as members of a colony, or as single or paired animals. About 75% of individuals live in colonies, 16% in “satellite sites”, and 7% in temporary sites. Satellite sites are secondary habitats consisting of only a few burrows. Those in colonies are members of harems, groups consisting of adult males, and females and their offspring. All males and about 40% of females are recruited from outside the colony. Reproductive rates at “satellite sites” are lower than in colonies and have more size fluctuation and shorter residencies than colonies and temporary/transient sites.

Mating System: polygynous ; cooperative breeder

Yellow-bellied marmots reach reproductive maturity by two years of age. Hence, no female yearlings produce offspring. Only 25% of two-year old females produce a litter. The testes of adult males are enlarged for several weeks when they awake from winter hibernation and then eventually regress to become the same size as juveniles. There is one breeding season per year, which starts and is concentrated in the first two weeks after they awake from winter hibernation. Gestation lasts for approximately 30 days, and litter sizes range from 3 to 8 pups, with an average of 4.32 pups. Adult females have an average corpus luteum count of 4.7. Newborn pups are 111 mm in length and weigh 33.8 g on average.

Breeding interval: Marmota flaviventris breeds once yearly.

Breeding season: Most Marmota flaviventris populations breed during May and June.

Range number of offspring: 3 to 8.

Average number of offspring: 4.32.

Average gestation period: 30 days.

Average birth mass: 33.8 g.

Average weaning age: 7 weeks.

Average time to independence: 7 weeks.

Average age at sexual or reproductive maturity (female): 2 years.

Average age at sexual or reproductive maturity (male): 2 years.

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

Average birth mass: 33.8 g.

Average gestation period: 30 days.

Average number of offspring: 4.

Average age at sexual or reproductive maturity (male)

Sex: male: 730 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 730 days.

There is little information available regarding parental care in yellow-bellied marmots. Mothers nurse pups for about 3 weeks, at which time pups emerge from the burrow. Parental care decreases substantially once pups emerge; however, strong social bonds remain for an extended period, especially in colonial populations.

Parental Investment: altricial ; female parental care ; pre-weaning/fledging (Provisioning: Female); post-independence association with parents

Mating typically occurs shortly after emergence from hibernation. Gestation lasts about 30 days. Litters vary in size between 3-8 young/year. Young remain in burrow for 20-30 days (Frase and Hoffmann 1980), emerge from the natal burrow in late June or July in the mountains of western Colorado, but range-wide reproductive timing varies with elevation and the timing of snow melt. At the highest elevations, females rarely produce litters in consecutive years (Armitage 1991). Males typically first breed at age three or older (Armitage 1991).

Yellow-bellied marmots are classified as a species of "least concern" on the IUCN's Red List of Threatened Species. Currently, there are no major threats to the long-term persistence of this species.

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Yellow-bellied marmots are known carriers of the plague, caused by the bacterium Y. pestis. Although uncommon, humans that come into direct physical contact with this species may be at risk of contracting the plague.

Negative Impacts: injures humans (causes disease in humans )

In certain regions of its geographic range, Marmota flaviventris is killed for sport, food, or fur.

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