John Beech – Land Management Adviser
Hygge (pronounced hoo–gah) has been a major trend for this Christmas period. It’s a Danish ‘concept’ of living cosily e.g. wearing thick socks whilst drinking hot chocolate and watching Murder She Wrote – which can make us feel better about the icy and harsh season outside.
For a number of wild animal species, they have their own version of hygge except for them it’s a necessary survival mechanism. Hibernation is an extended period of deep sleep, or torpor*, which allows animals to survive the winter extremes. By reducing their metabolic rate and lowering body temperature this enables them to sit tight, conserve their energy and survive through the cold periods when food is scarce or has little energy value. *Animals in a state of torpor rather than sleep can venture out to try and find additional supplies during warmer winter spells.
In autumn as the temperature begins to fall and the nights draw in, many of the small mammals that live in our fields, woodlands and hedgerows forage for extra food to store over the winter and look for a suitable site (a hibernaculum) to hole up in for the coldest part of the year. Autumn months are often one of the better times of year to see small mammals in the North York Moors such as mice, voles, shrews and Hedgehogs (Erinaceus europaeus) out and about eating vast quantities of food to build up fat reserves which will carry them through to the spring. Following this period of feasting they retreat to somewhere suitably warm and undisturbed and begin to enter into a period of hibernation, which can last for up to four months of the year depending on the harshness of the weather. Also in autumn bats relocate to hibernation roosts looking for a constant temperature and to avoid frosts and freezing e.g. caves, trees and built structures.
And it’s not just our small mammals that hibernate: Queen bees dig in for the winter and also some species of moths and butterflies, like the Duke of Burgundy (Hamearis lucina) which hunker down in grassy tussocks. Many of our reptiles and amphibians also hibernate. Adders find warmer crevices under boulders or in dry stone walls. Newt species spend the winter in the muddy banks of ponds, under paving slabs, piles of wood or in a handy compost heap. Common Toads (Bufo bufo) sleep out the winter buried deep in damp places such as leaf piles or compost heaps, before emerging to travel back to their traditional breeding sites in early spring. The Common Frog (Rana temporaria) which needs to keep damp is able to partially freeze in its state of hibernation before thawing out in spring. Occasionally such species come out of hibernation during any short sunny spells in the winter to make the most of the weak sunshine, only to return to their hiding place when the temperature falls again.
So as you’re reading this, hopefully somewhere cosy and warm, spare a thought for our wildlife that’s out there sleeping through the winter, hidden away from view deep in their retreats, practising their own life saving hygge and waiting for the first signs of spring.