• Hibernation occurs when an animal becomes inactive, or "sleeps," during the short, cold days of winter.
  • Hibernating and dormant mammals include bears, squirrels, groundhogs, raccoons, skunks, opossums, dormice, and bats.
  • Frogs, toads, turtles, lizards, snakes, snail, fish, shrimp, and even some insects hibernate or are dormant during the winter.
  • To prepare for hibernation, many animals eat to gain weight in the summer and fall. The extra fat keeps them alive during the winter.
  • A black bear can gain up to 30 pounds a week during its pre-hibernation eating binge.
  • During the fall, hibernating animals prepare nests for their winter sleep. Some store extra food in their nests.
  • Some hibernating animals wake for short periods during hibernation to eat and relieve themselves. Others sleep through the entire winter.
  • During hibernation, the heart rate for many animals slows to less than 10 beats per minute. Breathing also slows.
  • A hibernating animal has internal controls that prevent its body temperature from falling too low. The animal will wake up if its temperature is too near the freezing point.
  • Some female bears have babies during hibernation.