Hi Carlycat
Really sad to hear the news about the hedgehogs there.
I have to ask this question, but are you absolutely certain they are dead. It isn’t always easy to tell whether they are dead or hibernating. Apparently, it is unusual for hedgehogs to die curled up. A hibernating hedgehog will be curled up with their face tucked in and cold – hibernation is when their metabolic rate slows right down to only just keep them ‘ticking over’ so their body heat falls dramatically as part of the process. I have heard that you can tell if they are alive by gently stroking their spines and seeing if they ripple. You may have tried that yourself.
Having said that, hibernation is probably the most dangerous natural time for a hedgehog. They need to have sufficient supplies of two particular types of fat – one type to keep their metabolism ‘ticking over’ and the other to boost their metabolism into action again at the end of hibernation. If the levels of these are not sufficient they may either not be able to keep ‘ticking over’ or be unable to boost their metabolism into action again.
Sadly, not all hedgehogs make it back from hibernation. As well as the situations mentioned above there are numerous opportunites for disturbance. (Potentially: flooding, predators, human activity.) Whilst some hedgehogs do emerge for short periods during hibernation, if that is a result of disturbance (i.e. not the hedgehogs own choice) it could mean that too much of the ‘boosting’ fat is used up which could mean there is not enough to boost them again at the end of hibernation in which case they would die.
Females who have had late litters can be particularly at risk hibernating, as can late youngsters. It takes a huge amount out of a mother hedgehog to raise her young. They grow very quickly from the milk she provides for them. Having a late litter then leaves her very little time to put on the appropriate types of fat needed for hibernation. I imagine it’s possible that her instinct to hibernate may be stronger than her need to stay out of hibernation and feed herself up and natural food availability or lack of it may play a part.
The young, similarly, may not have time to put on enough of the appropriate fats to hibernate and so, for the same reasons, may not survive. That is why there are so many people trying to help any very smalll youngsters who are around late in the year.
So there are reasons why a hedgehog might not make it through hibernation, it’s just even more sad on a personal level if they are individuals you have got to know.
If I’ve interpreted your post correctly, one of the youngsters is still alive? In which case I hope it does well. Good luck.
