As the days become shorter and cooler, animals automatically begin to eat more, and to store what they do not eat. It is as though their bodies are telling them that in the months ahead, food will be scare.
Fruits and nuts are plentiful in the forest during autumn. So, animals like bears and woodchucks eat and eat till they are stuffed, to build reserves of fat that will see them through the long months in hibernation.
Migrating birds also build up reserves of fat before they start on their long flights to warmer places.Chipmunks and squirrels gather all the nuts they can find, and hide them in preparations are complete, an animal goes into its den, cave, or hollow log, where it can sleep through the cold winter.