1. In the coming weeks, bears, squirrels, marmots, and many other beasts will emerge from hibernation. An extended period of inactivity might sound relaxing, but hibernation is very different from rest.
2. Actually, it would be more like having a stroke. Oxygen flow to the gray matter of hibernators can drop to as little as 2 percent of normal.
3. Metabolic activity and heart rate also plummet. A ground squirrel’s heart rate can drop from 300 beats per minute to three or four ticks in the same span during hibernation.
4. It’s not just for winter: In tropical Madagascar, the fat-tailed dwarf lemur crawls into tree-holes and shuts down for an average of seven months to deal with a dearth of food and water during the dry season.
5. Warm-weather hibernation, or estivation, is also used by lizards, snails, and turtles.