Food Habits Little is known about the food habits of hoary marmots. They are mainly herbivorous, and in the spring and early summer, hoary marmots eat leaves and blossoms of many different herbaceous plants and grasses. Late in the summer, hoary marmots like to eat plenty of seeds. There have been a few cases of hoary marmots being carnivorous or even cannabalistic. Cannibalism most likely resulted from scavenging, as there have been no observed fatal fights between hoary marmots.
Hoary marmots appear to drink almost daily and they have frequently been observed eating snow.
The young stay in their mother's burrow until they are approximately one month old. At this time they are fully-furred. Because they spend their first month underground, it is difficult to know how well developed the young are at birth. Once the young have emerged from the burrow, they will be weaned in about two more weeks. Hoary marmots reach sexual maturity at two years of age.