Student Article

When the seasons turn harsh, animals use remarkable strategies to survive. From hibernation to torpor, let’s dive into the fascinating world of animal dormancy.

Hibernation: how animals sleep through the cold and heat

Hibernation is a survival strategy that allows animals to endure extreme conditions. During hibernation, an animal’s metabolism slows drastically, conserving energy. Its body temperature can drop to near-freezing, and its heart rate may slow to just a few beats per minute. Mammals like bats, hedgehogs, and ground squirrels rely on hibernation to survive the winter without food.

Hot weather sleep: aestivation

While hibernation happens in winter, aestivation is a warm-weather survival tactic. Snails, frogs, and lungfish enter a state of reduced activity during hot and dry months. By slowing their metabolism and remaining inactive, they avoid dehydration and heat stress.

Torpor: brief energy breaks

Unlike hibernation, torpor is a brief state of dormancy, often lasting only hours or days. Hummingbirds and bats use torpor during cold nights to save energy. While in torpor, their metabolism slows, allowing them to survive without needing to eat frequently.

Denning: light sleep for bears

Bears do not hibernate fully. Instead, they enter denning, a lighter form of dormancy. Their body temperature drops slightly, and they can awaken if disturbed. Female bears even give birth while denning and nurse their cubs during this time.

How do animals prepare to hibernate?

Animals use these strategies to survive tough conditions. Before they hibernate or aestivate, they eat extra food to store fat. This fat gives them the energy they need while they sleep through the harsh season.

The risks of hibernation

As global temperatures rise, hibernation cycles are being thrown off balance. Warmer winters cause animals to wake prematurely, reducing their survival chances. A 1°F rise in temperature can shorten hibernation by over a week, leaving animals vulnerable to starvation due to the lack of available food.

Fun fact!

The North American common poorwill is the only bird known to hibernate! It hides among rocks and reduces its oxygen intake by 90%, with its body temperature dropping to around 41°F (5°C).

© Dominic Couzens / Our Media