Hibernation is an incredible survival strategy used by some animals to get through the harsh winter months when food is scarce, and the weather is freezing. During hibernation, animals’ bodies go into a state of deep rest, like a long, controlled sleep. Their heart rates slow down, their breathing become shallow, and their body temperatures drop significantly. This helps conserve energy since they can’t easily find food in winter.
Animals that hibernate
Here are a few examples of animals that hibernate and how they prepare for it:
Bears: Before hibernating, bears eat a huge amount of food to store fat in their bodies. This fat becomes their energy source during the months they spend in their dens. While in hibernation, their body temperature drops slightly, and they can go without eating, drinking, or even waking up for weeks.
Chipmunks: Chipmunks store food like nuts and seeds in their burrows during the fall. Unlike bears, chipmunks don’t stay asleep the entire time—they wake up every few days to snack on their stored food before going back to sleep.
Frogs: Some frogs survive the winter by burying themselves in mud or under leaves. Their bodies slow down so much that they almost stop functioning, and some even allow parts of their bodies to freeze. They produce a natural antifreeze to protect their organs and tissues until spring.
Bats: Bats hibernate in caves or other dark, safe spaces where the temperature stays stable. During hibernation, their heart rate can drop from hundreds of beats per minute to just a few beats per minute. This allows them to survive without eating until warmer weather returns.
How the science of hibernation works
The science of hibernation revolves around an animal's ability to dramatically slow down its bodily functions to conserve energy during periods of cold weather and food scarcity. This process is regulated by changes in their hormones and internal biological rhythms, allowing them to enter a state of torpor—a period of deep inactivity where metabolic processes are minimized.
Reduced metabolic rate: During hibernation, these animals’ metabolism slows down significantly to conserve energy. For instance, their heart rate and breathing slow to a fraction of their normal levels, reducing the amount of energy required to maintain their bodies.
Body temperature drop: Many hibernating animals lower their body temperature to match their surroundings, which helps minimize heat loss. Some species, like certain frogs, can even allow parts of their bodies to freeze while protecting vital organs with natural antifreeze chemicals.
Fat storage: Before hibernation, animals consume large amounts of food to build up fat reserves in their bodies. This fat is gradually broken down during hibernation to provide the energy needed to sustain life.
Hormonal regulation: Hormones like melatonin and insulin-like growth factors play a key role in signaling the body to prepare for hibernation. These hormones help trigger the processes that slow down bodily functions and store energy efficiently.
Periodically wake up: Some hibernators periodically wake up from their torpor to eat stored food, eliminate waste, or warm their bodies temporarily before returning to hibernation. This is especially common in animals like chipmunks and bats.
Hibernation is not just about sleeping—it’s about drastically changing how their bodies work to ensure survival. When spring arrives, they wake up, ready to return to their normal activities. It’s a fascinating example of how animals have evolved to thrive in their environments.
