
Marmots Hibernate for Up to Eight Months of the Year
Marmots have one of the longest hibernation periods of any mammal, sleeping from September or October until April or May — up to 8 months. During this time their body temperature drops from 37°C to as low as 3°C, their heart rate slows from 100 to just 3–4 beats per minute, and they burn stored fat reserves entirely. The entire colony hibernates together in a sealed, grass-lined burrow.