Marmota flaviventris (Audubon & Bachman, 1841)

Weight Range

Fully grown yellow-bellied marmots usually weigh between 1.6 and 5.2 kg (3 lb 8 oz to 11 lb 7 oz), with males typically heavier than females. Their weight fluctuates dramatically throughout the year: it is lowest in early spring and highest in early autumn.

Sex-specific Weight

Adult males usually weigh 3–5 kg (7–11 lb), while adult females typically weigh 1.6–4 kg (3+1⁄2–9 lb).

Body and Tail Length

They have a total body length of 47–68 cm (18+1⁄2–27 in), with a short 13–21 cm (5–8+1⁄2 in) tail covered in buffy, reddish, and black hairs.

Appendage Measurements

Their hindfeet measure 7–9 cm (3–3+1⁄2 in), and their small round ears measure 1.8–2.2 cm (11⁄16–7⁄8 in) in length.

Guard Hair Appearance

Yellow-bellied marmots have a generally frosty appearance; many of their guard hairs have pale tips and dark bands.

Skull and Head Markings

They have a broad, flat skull, a dark head, and a dark nose with a white furry patch.

Pelage Structure

Their fur (pelage) is made up of coarse, long outer hairs and a shorter, woolly underfur.

Coat Coloration

Their main coat is brown, with a white patch of fur on the snout in front of the eyes.

Namesake Feature

They get both their common and scientific names from the bright yellow fur covering their belly, the sides of their neck, and their throat.

Facial and Back Coloration

They have a short white muzzle. Their back is reddish-brown, with a grizzled mix of black and light-grey tan, and their feet range in color from yellowish to dark brown.

Hibernation Preparation

In autumn, they build up extra fat reserves to prepare for hibernation.

Lifespan

Their average lifespan is 15 years, which is relatively long for their body size.

Lifespan Correlation

This longer lifespan is common among hibernating species, as hibernation has been shown to slow the process of epigenetic ageing.

Native Range

Yellow-bellied marmots are native to southwestern Canada and the western United States, including the Rocky Mountains and the Sierra Nevada.

Range Extent

Their range extends north into southern British Columbia, east into the montane and basin regions of Wyoming, eastern Montana, Colorado, and southern Alberta, and south into northern New Mexico.

Habitat Types

They live in steppes, meadows, talus fields, and other open habitats, and sometimes occur on the edges of deciduous or coniferous forests.

Elevation Range in Colorado

In Colorado, they are found at elevations ranging from as low as 1,600 m (5,400 ft) to over 4,300 m (14,000 ft).

Low Elevation Occurrence

In central and eastern Washington, they are common at low elevations.

Habitat Preferences

They occupy valleys, meadows, and foothills, and tend to live in open areas with little to no vegetation.

Territory Size

A marmot territory covers about 2.5 hectares (6 acres), centered around multiple burrows dug over the summer.

Burrow Placement

While marmots will sometimes burrow underneath trees and buildings, they most often dig burrows under rocks, as these locations are less visible to predators.

Predators

Common predators of yellow-bellied marmots include foxes, dogs, coyotes, wolves, and eagles.

Anti-predator Behavior

When a marmot spots a predator, it whistles to warn other nearby marmots, then typically hides in a nearby rock pile until the threat has passed.