Chipmunks survive in the winter through means of hibernation and food storage. They do not sleep all the way through to the spring; instead they lower their heart and respiratory rate so there is less need for energy. During hibernation, chipmunks are able to drop their body temperature from 94 degrees F to however cold their burrow may be (this can be as low as 40 degrees F), and lower their heart rate from 350 beats per minute to about 4 beats per minute. This state lasts only until the chipmunks wake (every few days), raise their body temperature back to normal, and eat some of the food that they stored over the summer and fall months. This process of sleep and wake continues until the end of winter or whenever the temperature raises again.
