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A Long Winter Snooze

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Posted: Thursday 16th November 2017 by WildBlog

By Rachael Fickweiler, Living Landscape Manager

For most animals, finding enough to eat in winter can be difficult when the main sources of food like insects or green plants are in short supply. Some animals solve this problem by hibernating. Hibernation is a deep sleep where the metabolism slows to help save energy and survive the winter without eating much. During hibernation an animal’s body temperature drops, and its heartbeat and breathing slow down so that it does not use much energy.

Hibernating animals get ready for their winter sleep by eating extra food and storing it as body fat which they then use as energy while sleeping. Some animals, including frogs and toads, go into a state called ‘torpor’ rather than full-blown hibernation which involves a significant drop in body temperature. They shelter under logs, rocks and fallen leaves or at the edge of water. When the weather gets colder, they may move down to the bottom of ponds and some even burrow into the mud. Some insects also hibernate and to get some shelter they find holes in the ground, under tree bark or in rotting logs.

Hedgehogs are one of only three British mammals that hibernate. The others are dormice and bats. When a hedgehog begins hibernation its body temperature drops to almost match the temperature outside; the heart rate will slow down from 190 beats per minute to a mere 20. Breathing almost stops altogether, with just one breath being taken every few minutes. This means the hedgehog can save its energy - surviving through the winter months on the fat reserves it built up foraging for beetles, caterpillars and earthworms during the autumn months.

Dormice hibernate in an underground or ground-level nest between October and April or May. Before they hibernate they fatten up to twice their normal size and can lose up to half of their bodyweight during hibernation. All 17 species of British bat hibernate during the winter months when insect food is scarce. They head for the hollows of trees, roof spaces, caves, cellars or even purpose-built bat boxes. Most butterflies spend winter in the larval stage, but there are a few including brimstone, peacock, comma, small tortoiseshell and red admiral that hibernate as adults in sheds and farm buildings or dense undergrowth like ivy as the cold sets in.

On our Avon Wildlife Trust reserves we create diverse habitats that meet a range of needs for our wildlife, from feeding and nesting to shelter and fresh water. We try to provide good opportunities for many species to survive winter on our reserves by retaining patches of scrub, creating log piles and keeping old and gnarled trees. We manage our ponds to create shallow edges and good levels of vegetation to provide cover and we keep areas of long grass and dead vegetation stalks to provide shelter for small mammals and insects. We put up bat boxes on trees and buildings and deep leaf litter carpets on our woodland floors giving warmth and shelter. You can create places in your own gardens to help wildlife survive the winter months by creating a pond or a compost heap, making log piles and leaving grassy or herbaceous vegetation uncut over winter - so don’t be too quick to tidy up!

To find out more about our nature reserves and plan an autumn visit our reserves page

Photo credits: autumn (c) Claire Davey; dormouse (c) Danny Green; hedgehog (c) Tom Marshall; reserve (c) Rosie Maple.


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