For many animals, finding enough food in winter can be difficult, because their main source of food such as insects or green plants is in short supply. Some animals solve this problem by hibernating.

What is Hibernation?

Hibernation is when an animal slows its heart rate to save energy and survive the winter without eating much. Some animals just slow down and move less frequently during hibernation, but others  go into a deep sleep and don’t wake up till spring.

During hibernation the animal’s body temperature drops, and its heartbeat and its breathing slow down so that it does not use much energy.  Some hibernators go into such a deep sleep that it is almost impossible to wake them, and they appear to be dead!

Hibernating animals get ready for their winter sleep by eating extra food and storing it as body fat which they then use as energy while sleeping.  There are two types of fat – regular white fat and brown fat.  The brown fat forms patches near the animal’s brain, heart and lungs. It sends a quick burst of energy to warm these organs first when it is time to wake up.

If the temperature falls too low, some animals will awaken slightly and shiver to warm up a bit. Hibernators may also wake up for a short period every few weeks to go to the toilet and eat a little food if it is available.


Image: Hibernation by Doug Brown

WWT (October 2019) Which animals hibernate in the UK? And how you can help them. [Online] Available from: https://www.wwt.org.uk/news/2019/10/28/which-wetland-animals-hibernate-in-the-uk-and-how-you-can-help-them/17887/ [Accessed on 23/11/20]

Which animals hibernate?

 Many different kinds of animals hibernate, from mammals and reptiles to amphibians and even some insects.

Bears are well known for hibernating, but they only do so if they live in a cold climate. Bears that live in warmer climates, such as the sun bears of South East Asia have access to plenty of food all year round, so they don’t need to hibernate. 

[photo; Zoë Helene Kindermann]

In the UK, only three mammals truly hibernate by sleeping right through the winter. Hedgehogs, bats and dormice hibernate from October or November each year right the way through to April or May the next year.   Many people think that squirrels hibernate, but they are actually not capable of putting on enough body fat to survive all winter without eating. Squirrels prepare for the winter by hiding food through the Autumn months, so they can eat this during the colder months. They are very good at remembering where they have hoarded their food! 

Some types of tortoise hibernate, including those kept as pets. Even though the temperatures inside a house might be warm, it can be very bad for a tortoise that is a hibernating species to be kept awake during the winter season. 

Some fish, frogs and turtles, which have no way to keep warm during winter, shelter under logs, rocks and fallen leaves in the water. As the weather gets colder, they move down to the bottom of lakes and ponds and some even burrow into the mud.

Some insects, such as bees also hibernate. Huddling honey bees huddle close together in their hive to stay warm, whereas burrowing bumblebees dig a tunnel in the ground and crawl inside through the winter. 

Why not carry out some research to find out some more animals that hibernate during the winter? 


How can you Help Hibernating Animals in the Winter?

You can help hibernating animals by providing them with a cosy place to sleep through the colder months. In Autumn, why not set up a hedgehog house, or build an insect hotel (link).

Before having any garden fires, make sure you check piles of wood for creatures such as hedgehogs that might have crawled inside. Generally, you should only light fires that you have built that day.

If you have a pond, don’t smash any ice that forms on the top, in order to let air through. This can upset hibernating fish and amphibians. You can melt a hole in the ice using an empty, hot pan (getting help from an adult if necessary so that you don’t burn yourself).

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