Common Poorwills don’t sing much when the mercury drops. But they can do something else that is remarkable. As the winter cold deepens, these petite members of the nightjar family can enter a hibernation-like state — and stay like that for hours — or even weeks! Scientists call it torpor. It happens when an animal slows its body functions to conserve energy and heat.More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.