The yellowbelly marmot is occasionally found in rocky areas of Wind Cave National Park. It is a heavy-bodied rodent having overall yellowish-brown color with buffy yellow neck, hips and belly. It has yellow patches on each side of the neck, a creamy colored bar across the bridge of the nose and about the lips, pale brown feet, and a grizzled brown tail.
Yellowbelly marmots live in a nest site among a pile of boulders, at the base of a slope or rockfall. They work their nest and burrow system into soil found under and between boulders to keep out predators. They live in groups, or 'harems', defended by a dominant male. Each harem usually consists of more female members than male. Hibernation starts as early as August for some of these rodents, depending on their location. The young are born in spring, 3 to 8 per litter.
The marmot diet includes forbs, grasses, sedges, clovers, and alfalfa.
Marmots are called groundhogs by people in the eastern United States. This is the animal that people watch to see if they see their shadow on Groundhog Day.