During the winter months, hedgehogs’ food sources become scarcer and scarcer until the energy required to forage in the colder weather outweighs the energy gained from the remaining food available. This triggers hedgehogs to enter into a state of hibernation, which typically lasts from October or November until March or April, depending on the severity of the winter.
In the preceding months, hedgehogs will be more active and increase their fat stores in order to survive the winter. During hibernation, their heartbeat slows from 190 to 20 beats per minute and their body temperature drops dramatically to match that of their surroundings. Due to their heightened vulnerability during hibernation, most hedgehog deaths occur in the winter.
Once hibernating, a hedgehog may wake up for short periods of time and forage, particularly in bouts of warmer weather. This is normal behaviour, and unless the hedgehog appears to be underweight or in a state of distress, there is no need for it to be taken to a wildlife rescue.
In arid climates, hedgehogs may respond to the extreme conditions and reduced food availability by undergoing a similarly dormant state called aestivation.