In preparing for winter, true hibernators must build up fat reserves. They do this by eating as much food as possible during the late summer and fall, storing energy in the form of white or brown fat. Hibernating mammals have more brown fat cells concentrated across the back, shoulders and close to the organs than non-hibernating mammals. Brown fat can be metabolized quickly to produce energy and heat – a benefit when you need to increase your body nearly 100 degrees. Some examples of true hibernators include woodchucks, hedgehogs, and squirrels.
Reptiles, turtles, lizards and snake that are too small to migrate will enter a state called “brumation” during winter. Cold-blooded creatures are unable to generate their own heat so instead they will seek shelter in the unfrozen mud at bottoms of ponds or in the hollows of trees or caves to emerge at spring thaw.
Hibernation is an amazing adaptation used by creatures large and small, warm and cold-blooded. While the days shorten and the days get colder, keep an eye out for animals that are getting ready for winter!