When winter comes around, and the last of the bugs disappear until the spring, a particular group of flying mammals must find a way to survive the winter without their only food source. Bats, along with groundhogs and chipmunks, are one of the few groups of mammals in the Blue Ridge that enter a state of true dormancy or hibernation. This state of low activity and reduced metabolic rate is called torpor, a state of efficient energy consumption that lets bats go for up to a month without drinking, eating, or moving.