A hibernating Alpine marmot may breathe only 1–3 times per minute.
That exceptionally slow breathing rate is part of the Alpine marmot’s profound metabolic shutdown during winter. As hibernation begins, its heart rate falls to about five beats per minute, while breathing slows to just one to three breaths per minute. Its body temperature can drop close to the surrounding air temperature, although the animal’s physiology responds if conditions approach freezing.
This is not simply ordinary sleep. The marmot uses stored body fat as its winter fuel because it does not forage underground. Before hibernation, it feeds intensively during the short alpine growing season and prepares a lined burrow. Huddling with nestmates provides additional passive heat exchange, and larger hibernating groups generally have better survival prospects.
The slow respiration rate is a useful comparison point when people confuse different marmot species. Olympic marmots also become deep hibernators, but the figures in this question refer specifically to Alpine marmots. Their breathing, heart rate and temperature all rebound during periodic arousals or when the burrow becomes dangerously cold.