The Big Sleep
Hibernation and Aestivation
When conditions get tough, some animals pack up and head for better climates. Others dig in and wait for things to get better. To protect themselves, they may go into a state of inactivity called hibernation (in cold climates) or aestivation (in hot ones).
When an animal does this, body processes like breathing and heartbeat slow down greatly, allowing the animal to conserve energy and go without food or water for long periods of time. When conditions improve, the animal wakes up and resumes its normal activities.