Winter is generally a quieter time in the wild world, with many of our favourite species disappearing from view. The colder temperatures, shorter days and decreased availability of food means that winter can be tough for wildlife, but as always with nature there is an answer! Whether it is leaving our shores for somewhere warmer, growing a lovely thick winter coat or hibernating, many animals know just how to cope with winter.

What is hibernation?

Hibernation is a period of significantly reduced activity where an animal’s bodily functions either completely stop or are drastically reduced. For example, heart rates may decrease by up to 90 per cent, body temperatures lower and metabolic rates slow down significantly too. This all allows animals to survive without eating or drinking for a period of months.

Is hibernation the same as being asleep?

No, hibernating animals may look like they are simply asleep, but in fact they are closer to being dead than asleep. Their breathing will be shallow and infrequent, and they will be cold to the touch. This helps the animal to avoid discovery by predators whilst they are hibernating as they give off less of a scent, make no sound and hardly move.

Whilst hibernating animals may wake up every now and again during their hibernation period – usually as a result of the weather warming up a bit and them needing a quick toilet break, snack or to move to a safer location – coming back to full wakefulness may take up to an hour. Animals will also wake from hibernation if their bodies are in danger of freezing due to drastic drops in temperature.

Why do animals hibernate?

Hibernation is what allows animals to survive the winter, as there simply wouldn’t be enough food to sustain their usual levels of activity. By feeding themselves up in summer and autumn when food is more plentiful and hibernating through the winter, this allows them to stretch out those reserves of food over the winter months.

Which animals hibernate?

Only three of our UK species actually truly hibernate; bats, hedgehogs and dormice.

A number of other animals enter states similar to true hibernation over winter:

Torpor

Some of our larger mammals such as badgers and squirrels enter an involuntary state called torpor during harsh winter conditions. If the weather is particularly inhospitable, they will retreat to their nests or burrows and enter a ‘mini-hibernation’ where their body temperature and metabolic rate decrease and their activity significantly lessens. However, torpor tends to be much shorter than full hibernation and the animals are able to ‘wake up’ much more quickly.

Diapause

Diapause is a unique state which some insects enter into in winter. Rather than hibernation when everything slows down for a while, diapause is a literal pause in their life – they enter a state of suspended animation. Diapause can occur in any life stage, often as a larva over winter. Or you may find a peacock butterfly in diapause in your garden shed and in really cold weather you may even see ice on them. But don’t worry, prior to diapause the insect will release anti-freeze chemicals into their body which will help them to survive.

How long do animals hibernate for?

In the UK our hibernating species tend to enter hibernation around November, normally returning to full activity by March or April. Exact dates will depend on the weather conditions that year. Climate change is posing an increasing threat to our hibernating animals as disrupted weather patterns may result in them entering or leaving hibernation at the wrong times, often causing them to wake before there is enough food around to sustain them.

Where do animals hibernate?

Hedgehogs will often hibernate under compost heaps, in piles of leaves and twigs, or under sheds and garden decking. Dormice weave tiny almost spherical nests from dead grass and leaves, which they position anywhere warm and moist to avoid dehydration as water vapor is lost when they breathe. Dormice nests can often be found at the base of hedges, or under logs or moss.

Bats choose hibernation roosts, most famously in caves, but they can also be found in bat boxes, roofs and hollow trees. If you fancy a winter stroll, why not visit our lovely Mere Sands Wood nature reserve and check out the dedicated bat hibernaculum. An old viewing tower has now been taken over by bats for both their summer daytime snoozes and their winter hibernation.

How can I help hibernating animals at home?

There’s lots of things that you can do to help hibernating animals at home:

• Leaving messy areas in your garden and making piles of logs, twigs and leaves helps provide places for hedgehogs to hibernate. Or why not make them their very own hedgehog house?
• Not cutting back your garden plants until spring will give lots of places for insects to shelter the winter away.
• Solitary bees will often seal themselves into the hollow stems in bug and bee hotels over winter.
• You can help our hibernating creatures by making sure there is lots of food for them in autumn. Don’t use pesticides and herbicides in your garden to make sure there are lots of insects for bats and hedgehogs to feast on, and you could leave some hedgehog food out too.

Find out more things that you can do in your garden to help wildlife in our blog:

Winter gardening for wildlife