A hibernating brown bear can have an approximate heart rate of 8 beats per minute. That figure describes the very low end commonly reported during winter dormancy, when the bear’s metabolism and physical activity are greatly reduced. An active brown bear’s heart rate is much higher, commonly around 40–70 beats per minute depending on activity and measurement conditions.
The exact rate is not fixed. Brown bears experience periods of changing activity, arousal, and respiratory-linked heart-rate variation inside the den. Research on free-ranging Scandinavian brown bears has recorded higher average hibernation rates, around the mid-20s beats per minute, while other observations report resting or minimum rates near 8–12 bpm. Thus, 8 bpm is best understood as an approximate low value, not a universal average.
This dramatic slowdown helps conserve energy while the bear lives mainly on fat accumulated before winter. Unlike small mammals that cool nearly to ambient temperature, bears maintain a comparatively high body temperature and can be roused more easily, yet still achieve substantial metabolic savings.