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Hedgehog Hibernation
Hedgehogs are one of three mammals in the UK that hibernate.
Along with the dozing dormice and snoozing, bats hedgehogs are well known for their winter naps but changes are afoot on our winter evenings
You see, hedgehogs, the cool creatures they are, can survive well in cold weather – but they cannot survive without food.
Like many other keen nature watchers, we have seen changes in behaviour over the last decade, including the humble hog. Hedgehogs are no longer hibernating as they used to. Some are sleeping only for days and then reappearing for short spells. Could this be down to climate change, or is there a more straightforward explanation?
Let’s start by finding out why some animals hibernate.
Animals hibernate because food supplies become scarce. Hibernation happens in areas where the climate has a high percentage of change between seasons. It is usually associated with extreme cold but also happens in hot climates. This is known as aestivation.
Hibernation is a state of minimal activity and metabolism depression. Hibernation can be characterised by low body temperature, slow breathing, slow heart rate, and a low metabolic rate. Most calories “warm-blooded” animals burn go into maintaining the basal metabolic rate. The metabolic rate is the use of energy expenditure per unit of time by an endothermic animal. An Endotherm is an organism that maintains its body at a metabolically favourable temperature, largely by the use of heat, set free by its internal bodily functions instead of relying almost purely on ambient heat
Hibernation is a risky business and many don’t survive. During hibernation, a hedgehog’s heartbeat slows from 190 to 20 beats per minute and their body temperature drops dramatically to match that of the ambient temperature in the nest. Their body temperature which is usually around 35°C drops to 10°C or less, and their new low respiration rate means they will breathe just once every few minutes. This helps them to conserve energy for a long sleep.
In the UK, it’s around September and October when hedgehogs start looking for safe places to hibernate. Popular hibernation sites include fallen trees, woodpiles or under garden sheds, They love compost heaps, greenhouses, garages and any other undisturbed space they feel safe in. They have been found under tarpaulins, old grab bags, in barbecue covers and under an upturned paddling pool.
Gardens often provide an ideal range of potential hibernation sites for hedgehogs and may also include a reliable source of water and food. That combination is heavenly for a hedgehog. One word of caution, if you are intending to do any work overwinter in your garage, sheds, or outbuildings – is to check for hedgehog nests before you start work. Hedgehogs can hibernate in the strangest of places to us… but the Hedgehog has chosen that place as it fulfils their needs for the long sleep. Maybe it successfully hibernated last year in that space. One thing you can be sure of is the hedgehog won’t have a backup plan – so please do check carefully
A hedgehog disturbed from hibernation will be unlikely to get back to sleep without help and care although they have been known to build a new nest once disturbed. It takes a hedgehog around 20 to 30 minutes to raise its body temperature and heart rate as it wakes from hibernation and it uses a lot of energy. Once awake, Hedgehogs will need to find food to restore the energy they have used. Of course, there is no natural food and their water source may well be frozen. This could spell big trouble for the hedgehog.
If you do disturb a hedgehog from hibernation We strongly recommend you contact your local Wildlife Rescue and follow the advice they give you.
Further Reading
Hibernation by The Amazing Grace Hedgehog Project
Hedgehog Hibernation by BHPS British Hedgehog Preservation Society
Hedgehog Hibernation by Hedgehog Street
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