Animals exhibit many different types of dormancy. One of them, hibernation, refers to inactivity and metabolic depression associated with low temperatures or food deprivation. Hibernation is characterized by low body temperature, slow breathing and reduced heart rate and a low metabolic rate. Obligate hibernators are animals that hibernate regardless of temperatures or access to food, while facultative hibernation refers to animals that enter hibernation when cold stressed or food deprived, or both. Facultative hibernators enter hibernation in winter, but emerge when the weather is nice. These animals may hibernate and wake several times during a winter.
Yellow bellied marmots (Marmota flaviventris) are examples of obligate hibernation. These rodents hibernate in burrows and dens from approximately September or October and emerge in April or May. They dig their dens under piles of rocks or tangles of tree roots where predators (including man) have a difficult time finding and reaching them. Yellow bellied marmots spend about 60% of their lives hibernating.
Living at higher elevations, yellow bellied marmots prefer a habitat of rock piles in grassy meadows. Emerging from their dens in the spring, yellow bellied marmots are thin. During the summer they feed avidly by day on grasses and other woody and herbaceous meadow vegetation. By fall when the marmot is ready to again hibernate, its body is thickly layered with fat to provide sustenance over the winter.
This yellow bellied marmot was watching Leonard and I from behind some logs along Modoc County CA Road 87 near the Pit River overflow. The opportunity for a good photograph did not present itself, but watching this cute little marmot entertained us for a few minutes.