"HIBERNATION

Many warm-BlOODED ANIMALS need extra energy in order to stay warm in the cold winter months, but the source of that energy - food - is scarce in winter. some animals survive winter. by migrating to a warmer place: other, such as bats and unexposed place such as a nest, burrow,  or cave. In true hibernation, the body processes slow down almost to a standstill -the heartbeat, occurs only every now and then, and the lungs breatbeat very now and then,  and the lungs breathe very showly. The body temperature - falls to only a few degrees above the outside temperature (as 32 F (0 C ) in a hamster.  If the outside temperature drops below zero, chemical reactions in the animal's body switch on to keep it from freezing to death.  A hibernating animal feasts on extra foody in the fall so it can build up reserves of fat in its body and survive the winter months without food.                  Fonte: the randon house. encyclopedia