The squirrel, a warm-blooded animal, hibernates during the winter.
Both warm-blooded and cold-blooded animals hibernate, including some species of squirrels, hedgehogs, frogs, turtles, and even some fish. Most animals that hibernate are found in the northernmost and southernmost areas of the globe, the world’s coldest climates. The range is quite wide and also includes hamsters, skunks and badgers. Bears, perhaps the most famous of these animals, do not sleep as soundly as many other animals, so some scientists do not consider this hibernation to be true.
warm blooded animals
Some cold-blooded animals, like the bullfrog, hibernate during the winter.
Many small, warm-blooded animals hibernate during the winter, including many rodents such as voles, ground squirrels, and marmots. These animals must hibernate for part of the year, and once this process begins, it is extremely difficult to wake them up. A hazel vole’s body temperature, for example, drops to just above freezing, and its heart beats only a few times a minute. Some of these animals wake up periodically to eat, but others remain in this deep sleep for up to six months. Other warm-blooded animals that hibernate include mouse lemurs and mountain pygmy possums.
Turtles often hibernate.
Most birds don’t actually hibernate, although the poor common ones, a species in the family called Nightjars or Nighthawks, do. Found in the southwestern United States and Mexico, this bird can spend weeks or months during the winter in a dormant state. Other birds may enter a state known as torpor, during which metabolism and body temperature drop, but this usually lasts only a short time, often overnight. In many cases, hibernation is described as long-term torpor.
Some hamsters hibernate.
Bears are the most commonly identified animals that sleep during the winter months; however, many scientists do not classify the bear as a true hibernator because it does not undergo the same degree of physiological changes as other hibernating animals. For example, while a bear’s heartbeat and breathing slow down, its body temperature doesn’t drop much. Along with some bats, bears are also relatively easy to wake up. Most bears give birth to their cubs during the winter, and therefore the mother bear must be somewhat conscious during the birthing process to properly care for her cubs.
cold blooded animals
Hedgehogs are animals that hibernate.
Insects, reptiles, and other species, including some fish, also hibernate. Because they cannot maintain their body temperature in the same way that warm-blooded animals can, many cold-blooded animals seek refuge in hollow trees, caves, or underground for protection during the winter. Some swamp creatures, as well as fish, often burrow into the mud at the bottom of a lake or pond. Not only does this protect the creature from the elements, it prevents the current from dragging the creature downstream and prevents it from becoming food for other non-hibernating predators.
Some scientists do not believe that bear hibernation is true.
Some experts make a distinction between the winter torpor periods of warm-blooded and cold-blooded animals. Instead of “hibernation”, they refer to it as “brumation” when it occurs in reptiles. The main difference is the power supply; mammals eat extra food before hibernating and use stored fat to survive the winter, while reptiles survive on glycogen, an energy storage molecule. However, for practical purposes, the two states are very similar.
How does hibernation work?
Bats are known to wake up easily when they enter their winter slumber.
Hibernation allows an animal to greatly slow down its life support systems, often with a single heartbeat over several minutes. This altered metabolism not only saves energy, but also prevents the animal’s body from requiring additional food and water while it sleeps. The animal’s body temperature also drops and most of the heat is concentrated near and around the vital organs. In some animals, such as the opossum, the young are born while the mother sleeps; the newborns make their way to a pouch in the lower part of the mother’s belly, where they nurse for the remainder of the mother’s hibernation period.
Opossums are an example of an animal whose babies are born while the mother sleeps.
In some cases, the weather can become unusually warm early in the season, causing animals to come out of hibernation much earlier than usual. This can often endanger the life of the animal, because food, such as grasses and berries, is not yet available. In this case, animals can go hungry and malnourished. Such a season can also endanger the lives of newborns, as their mother’s milk can dry up due to lack of nutrition from her.