Wake me up in spring

Many animals tuck themselves away to avoid the cold of winter, but these sleepy creatures are among the few true hibernators

Hedgehogs survive on their fat supplies

All through summer, hedgehogs in temperate climates pile on the fat to prepare themselves for their big sleep. To conserve energy during hibernation their body temperature drops to match the air temperature, their heart rate slows and they only breathe once every few minutes.


Winter is a perilous time for dormice

Hazel dormice usually stick to the safety of the trees, but they come down to the ground to hibernate every winter. Curling up in leaf litter and in tiny nests under hedges, they try to survive the cold and lack of food, but it’s thought that many of these dainty creatures don’t make it to spring.


Arctic ground squirrels become the coldest mammals

Each September, Arctic ground squirrels head underground to burrows lined with hair and grass. They’ll stay there for the next eight months, surviving the winter by slowing or shutting down their organs and letting their temperature fall as low as -2.9 degrees Celsius (26.8 Fahrenheit). Occasionally they’ll wake up and shiver to keep their brains functioning.


Bats make themselves as small as possible

You’re unlikely to see brown long-eared bats between November and April, because they’ll be hibernating in caves, tree holes and attics. Their huge ears would lose a lot of heat through these cold months, so the bats tuck them away under their wings, leaving just the tragus sticking out.


Hornet queens spend winter alone

As autumn approaches, hornet colonies raise queen larvae. When they’ve pupated, these new queens leave the nest in search of mates. They don’t begin laying eggs immediately though – first they find a cosy spot and settle down to wait out the winter. Old queens and their colonies die in the cold, but the new queens emerge in spring ready to start again.