These are the animals that hibernate in the UK in winter - and why they do it
Although rodents are the most common animals to hibernate, there are several mammals and insects which also sleep to conserve energy as the colder days require a higher body fat percentage and result in many food sources dying off.
Other types of animals which don’t hibernate also find ways of surviving the winter.
What is hibernation?
Often thought of as just sleeping, hibernation is actually a state in which an animal decreases its metabolic rate (the rate at which it burns calories) and body temperature.
The animal slows its heart rate and breathing to maintain a lower basal metabolic rate.
Why do animals hibernate?
Hibernation is a process animals use to store energy, which they lack during winter due to a reduction in food sources.
Without being able to hibernate, these animals would be at risk of dying because they would have to use energy to move around and stay warm while struggling to find food to top up their energy sources.
Which animals in the UK hibernate?
Only three mammals in the UK hibernate - hedgehogs, dormice and bats.
Hedgehogs hibernate from October through until March or April, depending on how quickly the temperature drops and picks back up again.
During this time, our jagged friends will only take a breath every few minutes and will maintain a temperature almost equivalent to the outdoors.
Dormice are much the same as hedgehogs in the months they hibernate, although they do so underground.
The tiny animals weigh somewhere between 80 - 130g and double in size prior to the winter as they will use almost all of this extra weight to stay alive while they sleep.
Bats tend to hibernate from November until March, waking at some stages to find food and take a toilet break.
Their reason for hibernating is largely due to the lack of insects available throughout the colder months.
Many species of insects hibernate, including ladybirds, butterflies and bumblebees.
While butterflies will hibernate alone, either wrapping themselves in their wings or in the chrysalis stage of becoming a butterfly, bumble bees and ladybirds huddle in their nests together to share conserved energy.
What can I do to help animals in my garden hibernate?
Should hedgehogs frequent your front lawn, there are a few ways you can keep them safe through winter.
Creating a compost or leaf pile in a dry and warm spot - under a tree or behind your garden hut - allows them to stay sheltered and warm. Also, be sure to check your garden over before cutting the grass or clearing away any piles of fallen leaves.
If you stumble upon a sleepy butterfly while cleaning out your storage cupboard, do not be alarmed as they cannot cause you harm and will die if woken as they cannot withstand the outside temperatures.
Instead, either leave them to rest or place them in a small shoe box with an air hole and they should wake in their own time.
Although bats may not be as cute as our hedgehog residents, they are vital to pollination and we should allow them to hibernate so they can make it into the following spring.
If you are a fan, you could make a bat box to attract them - otherwise you may find them in trees or in the roof of your barn, shed or outbuilding.
Leave them be and they will fly away when the warmer weather comes in, if they do not leave beforehand to look for insects.
Why do birds not hibernate?
While mammals, insects and even some reptiles use hibernation to tackle the adverse winter conditions, birds migrate instead.
Their ability to fly allows them to seek out warmer climates and countries where food is still in abundance.
As countries go through seasons at different rates and different times throughout the year, birds are attracted to wherever suits their preferred environment.
However, this is not the case for all birds - think Robins at Christmas - as some will migrate to the UK in winter and others never leave.
Instead, they will fatten up throughout the day to make it through the cold night.
The RSPB urges people to continue feeding birds throughout the winter as they will become reliant on the feeders you have hanging in the garden.
Can animals hibernate in the summer?
Yes, this form of hibernation is called aestivation and helps animals stay alive through drought, intense heat and when plants die out.
The ladybirds in the UK hibernate through the cold but in warmer climates other species of insect will sleep to withstand the lack of food when plants dry up and the ground is too hot for them to survive.
Mice and hedgehogs in other countries - such as Africa and Asia - also enter a state of hibernation when the temperature is exceedingly high.
However they do not keep their metabolic rate low for the same length of time as in the cold.
Mice will forage throughout the evenings and lay still all day to store water and energy while hedgehogs can remain asleep for as long as six weeks.