Animals that hibernate: who hibernates and what happens?

Animals that hibernate: who hibernates and what happens?
The dormouse is one of the only UK mammals that hibernates (Photo: WTML)

When winter arrives some animals hibernate, which means they go into a very deep sleep that helps them save energy and survive the cold weather when there’s not much food around.

Animals that hibernate: who hibernates in the UK?

The only UK mammals that really hibernate are the hedgehog, the bat and the dormouse, so it’s no good pretending you’re hibernating when you have to get up for school on a cold morning!

Many people think squirrels hibernate, but they don’t; they just stay inside their hidey holes a lot more, and who can blame them?

Similar ‘hibernators’ include:

  • Insects
    Including some adult butterflies and bumblebees
  • Amphibians
    Including frogs, toads and newts
  • Reptiles
    Including tortoises and snakes

Although they don’t really hibernate, these cold-blooded creatures have special anti-freeze in their blood that allows them to freeze without dying. So a frog frozen at the bottom of a pond can spring back into life once warmer weather arrives. This special power is called brumation.

What happens during hibernation?

Hibernation is very different to sleep. When an animal hibernates, its temperature drops, and its breathing and heart rate slow right down so it’s not using up very much energy.  A hedgehog’s heartbeat drops to about 20 beats per minute from its usual 190 beats, and some species of bat can go for nearly an hour without breathing!

Hibernators don’t sleep for the whole winter; they wake up every now and then to look for food and go to the toilet. They also have a sort of internal alarm that wakes them up if it gets so cold they’re in danger of freezing.

How to help hibernating (or very sleepy) creatures

Frogs, toads and newts sleep under rocks or bury themselves at the bottom of a pond. If you have a pond in your garden and it gets completely iced over, pour some warm water on it to make a hole to let some air in – they still need to breathe. Bashing the ice to break it may upset the sleepy heads.

Hedgehogs wake up every now and then to look for food, so put out some meat-flavoured cat biscuits (not fish-flavoured), chopped unsalted peanuts, or bought hedgehog food. Don’t put out wet food that might freeze. Make sure you put out some water too. It needs to be in a shallow bowl, and you can stop it freezing by putting a ping pong or tennis ball in it.

Hedgehogs need to weigh at least 500-700g to survive the winter. If you see a small one out and about, get in touch with the British Hedgehog Preservation Society (01584 890 801) for advice on how best to help it.

Did you know?

  • The name ‘dormouse’ comes from the French word ‘dormir’ (to sleep).
  • A bird called the common poorwill, which lives in the USA, is the only bird species known to hibernate.
  • If you feel frozen when you’re outside, spare a thought for the Alaskan wood frog: around 60 per cent of the water in its body turns to ice during the winter!

Spotted any signs of hibernating animals?

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