is a deep sleep which allows bats to conserve energy and survive the winter with little or no food. Bats that live where insect prey is scarce during winter will hibernate in houses, trees, or rock cavities; clustered on walls or ceilings. Hibernation can last over six months on only a few grams of stored fat! They drop their body temperature and slow their metabolism to achieve this. By spring, bats will lose half of their body weight.