Brief emergences may occur before the final emergence. Males are the first to hibernate, followed by females and young, which remain active to gain sufficient fat for hibernation. Daily activity mostly is bimodal. After a period of sunning, there is a mid-morning peak of foraging activty followed by another peak in late afternoon. This pattern is subject to seasonal variation.
Marmot colonies consist of one, or more, harems, each harem defended by a territorial male.
Mates in the first 2 wk after emergence. After a 30-day gestation, young born March to June, depending on elevation. Lactation lasts 20-35 days. Those young that wean early have more time to accumulate fat for hibernation, and a higher probability of survival through the winter. Yearling females rarely reproduce.