From the Winter 2010 Conservationist for Kids
By Gina Jack and Ann Pedtke
It takes energy to stay active and warm. Energy comes from food, which is often difficult to find during the winter. Some animals have adapted to survive winter by going through a long period of dormancy. During this special time, their bodily functions, like heart rate and breathing, slow way down. By hibernating, they conserve energy and improve their chances of surviving until warmer weather returns in the spring, along with more plentiful food.
Mammals are warm-blooded. When they're active, their body temperature stays pretty much the same. When mammals hibernate, their body temperature drops, breathing and heartbeat slow down, and they don't need as much food as when they're active. Depending upon the species, body fat put on in the late summer and fall may be enough to carry them through the winter, or they may wake periodically for a snack from food they've stored in their burrow.
Reptiles and amphibians are cold-blooded. Their body temperature goes up and down with the temperature of their surroundings. They will not survive out in the snow and ice. If you know where they hibernate, you'll know where to start looking for them when spring arrives.
Insects can't be active during the deep freeze, but that doesn't mean you won't see them. Depending upon the species, they may spend the winter as eggs, larvae and pupae and occasionally as adults.