This earth mound is at the main entrance to their homes. In addition, they usually build one to four escape holes that are harder to find. Escape holes are located in thick vegetation and are dug from under the ground, so there are no telltale mounds of dirt. They spend so much energy on their homes and tunnels because they have so many enemies, including hawks, owls, foxes, dogs, and us. They don't run very fast and usually stay fairly close to their emergency holes.
Woodchucks are among the few mammals that enter into true hibernation.
Beginning early November, they hibernate until late February or March. Their heart rate and temperature are drastically lower while they sleep. During the summer a woodchuck's heart rate is around 250 beats a minute, and it has a temperature of 100 degrees Fahrenheit. In the winter, it has a heartbeat of only 5 a minute, and its body temperature is only 37 degrees. When they emerge from their burrows they are not looking for their shadows, they are searching for a mate.