What happens to a hedgehog in hibernation?
Did you know that during hibernation, Hedgehogs are not just "asleep"?
Their bodies cool right down from around 35°c to as low as 10°C and sometimes lower.
Their heartbeat slows from 190 beats per minute to 20.
Their breathing mirrors this and they will only take a breath every few minutes. When they wake up they are going to want to SNACK!
How do we define and describe hibernation in hedgehogs?
A state of deep numbness during which these animals can react to stimuli.
During hibernation, breathing, heart rate and metabolism are minimized and body temperature drops.
One of the reasons why breathing slows down so much is to save on fluid loss while breathing during hibernation.
An unusual hibernation!
A hedgehog hibernates with a tortoise
on each side.
Hedgehogs are solitary but sometimes share a place to hibernate.
In winter with the arrival of low temperatures, insects and everything a hedgehog feeds on are scarce.The lack of food can be a factor in
The hibernation period of the hedgehog varies according to where it is found geographically throughout Europe.
The altitude of where it lives can affect this, and also the severity of the weather.
In our area (Northern Italy), due to the rise in temperatures, hedgehogs now hibernate from January and the re-awakenings have been noticed as early as the end of February.
This results in many more hedgehogs being found during winter months which are debilitated and also suffering from internal parasites.
Some of the information in this section is used with kind permission of The British Hedgehog Preservation Society (BHPS), British Wildlife Rehabilitation Council (BWRC), The Royal Society for the Prevention of Cruelty to Animals (RSPCA) and Vale Wildlife Hospital.
There is a lot of debate surrounding survival weights for hibernating hedgehogs and it is confusing for the public and rehabilitators alike.
We have also been alerted to the fact people are actively going out and looking for healthy hedgehogs to collect that are under 600g to take into care.
To try to address this, The British Hedgehog Preservation Society (BHPS), British Wildlife Rehabilitation Council (BWRC), The Royal Society for the Prevention of Cruelty to Animals (RSPCA) and Vale Wildlife Hospital put their heads together to try to come up with a simple to follow guide for rehabilitators that all four bodies would be happy to put their name to.
This document is a result of that collaboration.
WILD (free-living) hedgehogs
Advice to bear in mind when the public call about a hedgehog in the WILD
1. No specific weight will guarantee survival. Parasites, lack of food, disease or predation can cause death.
2. Regardless of the weight, a hedgehog should always be taken when it is in difficulty.
3. It is generally assumed that if a hedgehog weighing 400 grams goes into hibernation without having accumulated enough fat reserves it will not be able to spend the winter.
4. From 600 grams upwards, if healthy, most hedgehogs survive hibernation.
5. From October it would be advisable to take hedgehogs weighing less than 350 grams. Of course, the rules for the withdrawal vary according to the states, the territory and the climate.
6. A hedgehog that lives free in a garden where it has its refuge, food and water, can easily survive the period of hibernation.
7. Rescuing a hedgehog when it is not at risk, may lead to serious problems with stress and potentially make parasite infestation worse. All of which will need to be treated with drugs.
Once a hedgehog has been taken to spend the winter in protection, or to be cured until released, the advice we give is slightly different because the hedgehog will lose weight once freed.
Therefore the following advice refers to hedgehogs that are already under protection
CAPTIVE-REARED or JUVENILES
(Each reference to weight may vary according to which country, the terrain and whether it is low-lying or hilly.)
1. Captive hedgehogs put on weight quickly compared to wild counterparts of similar age (sometimes reaching double natural weight for that age).
2. They shed this excess weight on release and thus lose weight faster than wild hedgehogs.
3. They should not be released at weights below 400g in autumn (500g in very late autumn/early winter).
4. Greater weight (eg over 600g) may enhance survival, but there is no evidence for this.
5. Excessive weight is probably not beneficial and may be harmful. Hedgehogs in care at Vale Wildlife Hospital are put on a diet if they reach as much as 1kg when being over-wintered.
6. There is no telling exactly what weight will ensure survival.
Optimum weights for hedgehogs vary tremendously between individuals.
The optimum weight for one hedgehog could be for example 800g whereas another could be well within its normal weight range at 1100g.
Vale have found that keeping hedgehogs below 1kg in weight when overwintering has limited the number developing problems due to being overweight while in captivity.
First of all it is important to ensure that advice is based on data and sound research.
Whilst experience in the field of hedgehog rehabilitation is priceless, ‘hunches’ cannot be properly defended against somebody else’s hunch if that happens to be different.
It is also important to distinguish between wild hedgehogs and captive reared (rehab) ones, particularly with respect to body weights in autumn.
Sometimes acting with the best of intentions people can cause serious welfare issues for hedgehogs, so we hope this scientific advice will offer a little clarity and prevent hedgehogs from being taken from their natural habitat when not necessary.