Yellow-bellied marmots are rodents similar to squirrels, but bigger. They have grizzled brownish fur and a yellow belly, with a whitish spot between their eyes. Their ears are small and round and they have a short white muzzle with a black nose. Their bodies are heavy-set and they have short legs and a reddish-brown furry tail.
Yellow-bellied marmots have a wide range throughout Canada and the western United States, as far to the north as Alberta in Canada and south central British Columbia and as far to the south as the Sierra Nevada in southern California, Nevada, southern Utah, and the Sangre de Cristo Mountains in northern New Mexico. They generally live in fairly warm, dry habitats which are at low to mid elevation. They usually inhabit open territory, such as steppes, alpine meadows, fields or pastures. They use talus and rocky areas for cover, and if possible they will usually build burrows under rocky areas.
Yellow-bellied marmots are primarily diurnal and terrestrial. They can live in colonies, or as single or paired animals. Their basic social structure is one male with two or three females. Male marmots are territorial, and will aggressively defend their harem. The females are not agonistic, and will share the raising of offspring within the harem. These animals spend around 80% of their time in burrows in winter hibernation, which lasts about eight months from early September until May, but may vary somewhat from year to year. A marmot’s time above ground is mostly spent sunning itself, while its head is in an alert position. This species’ social interactions with each other are either agonistic or amicable, the latter including grooming, play and greeting behavior. The agonistic behavior includes social mounting, alert behavior, fighting and chasing. Amicable interactions occur between those individuals who share a burrow, while agonistic ones take place with those from different burrows.
This species has a "harem-polygynous" system of mating in which males reproduce with two or three mates during the same time period. The breeding season is within the first two weeks following winter hibernation. Most Yellow-bellied marmots mate during May and June. The gestation period is for about 30 days, 3 to 8 pups in a litter. The young start to leave their nest at about 3 weeks of age and are weaned by 5 weeks old. The adult male will drive out his male offspring when they wake from hibernation. Females are allowed to stay in the group. Sexual maturity is reached at two years old, although these animals do not mate until they are three years old.
There are currently no significant threats to Yellow-bellied marmots. Some people consider them a pest, but human hunting does not affect the stability of populations. However, habitat destruction and pollution are always a threat.
No estimate of population size is available for this species. Currently this species’ numbers are stable and it is classified as Least Concern (LC) on the IUCN Red List.
As seed predators, this species may act as habitat engineers, contributing to the composition and density of plant communities within their range. They are also important prey for a range of terrestrial and aerial predators. Once abandoned, their burrows probably provide important habitat for other species of a fossorial or semi-fossorial type.