Some animals, like bears and snakes, prepare for winter by hibernating. Hibernation is a deep sleep triggered by shorter days and colder temperatures that allows animals to conserve energy when food is scarce. Animals put on fat stores before hibernating and their heart rate and body temperature decrease significantly. Hibernation carries risks like animals becoming vulnerable to predators or extreme weather while sleeping through the winter. Common hibernating animals mentioned include bears, hedgehogs, ladybirds, snakes, and bats.