Animals that Hibernate

PUBLISHED: 09:29 21 January 2010 | UPDATED: 15:34 20 February 2013



The days are now short and the nights cold. The memories of summer warmth are distant and its time to get out those woolly jumpers and snuggle up by the fire with a mug of hot chocolate. But many of well-known garden friends such as hedgehogs

Critters that hibernate







Fact file

Gardeners love hedgehogs

because they eat slugs and snails and other creepy crawlies. It has been a wet summer, so hedgehogs will have benefited from the abundance of these molluscs. Hedgehogs are found across the UK mainland but do not like wet areas or coniferous forests. When threatened, they curl up and their spines protect them from predators such as foxes and birds of prey.

The dormouse is named because of its ability to be dorm-ant for most of the year! This popular orange-coated, fluffy tailed, large-eyed mouse weighs about the same as a conker! It eats seeds, flowers, nuts and insects. It sleeps by day and feeds by night in the tree canopy. In the Cotswolds, Gloucestershire Wildlife Trust's Midger Nature Reserve has a healthy population of dormice.

Most of the UK's 17 species of bats can be found in the Cotswolds. All hunt by night using echolocation to find and catch insects - they bark in short blasts and listen for the echo from the insect. A pipistrelle bat, weighing only 5g, can consume up to 3,000 midges and mozzies a night! Bats do not build nests or spread disease and can live in lofts without threat to the owners. During winter they hibernate.

In the Cotswolds we have the common frog, the common toad and three species of newt in our amphibian collection. Only the rare natterjack toad is absent. They are all cold blooded and eat invertebrates such as insects. They all depend on ponds for breeding in early spring but may spend a large proportion of their time away from the pond.

There are 59 butterflies resident in the UK which are part of the Lepidoptera family which includes moths. The limestone grasslands of the Cotswolds are home to many butterflies including the rare small blue. Adult butterflies suck nectar from flowers for energy and most depend on specific host plants on which to lay their eggs. The larvae (caterpillars) hatch and feed on the leaves or flowers, then pupate and later hatch into adults.

Of the three snakes found in the UK, two can be be found in the Cotwolds. The adder or viper is easy to identify with its dark zig-zag pattern along its back. This venomous snake is smaller than the grass snake which can grow to 60cm. The grass snake is grey/geen with black bars along the side and a yellow/cream to the side of the head.

Winter strategy

Hedgehogs will find a pile of leaves, cuttings or even a compost heap to bed down in for the winter. They will curl up into a tight ball and sleep. Energy reserves built up during a summer of gorging on all manner of insects and other invertebrates are used to keep the body going during the big sleep.

Dormice can sleep from October to May but usually doze off at the first frost -that is a long sleep! They will retreat to a small nest on or near the ground and curl up into a tight ball. Their breathing and heart rates will drop by up to 90% during hibernation and body temperature will be greatly reduced.

After mating in the autumn, bats hibernate in caves, tunnels, lofts and wall cavities. Old railway tunnels are a favourite. Only two species of UK bat hang upside down - the lesser and greater horseshoe bats but the rest crawl into cracks and cavities. They will wind down their breathing, heart rate and temperature and become torpid, saving energy for the spring when food is abundant.

Hibernation is a necessity for all amphibians. Frogs occasionally hibernate in mud at the bottom of a pond, but more usually, along with toads and newts, they hide themselves away under piles of damp leaves, rotting logs and in underground tunnels. In spring, the amphibians emerge to migrate to their breeding grounds and spawn.

Butterflies have a range of winter strategies. Some spend the winter as an egg waiting to hatch or a caterpillar waiting to crawl onto its food plant when it grows early in spring. Others such as the yellow brimstone and small tortoiseshell hibernate as adults, ready to fly on the first warm spring morning. Brimstones choose dense ivy for shelter whereas the tortoiseshell likes cool sheds and outbuildings.

Both the adder and the grass snake will crawl into a quiet safe place for the winter once it becomes too cold for them to move around and hunt. They will often choose piles of cut vegetation or manure heaps, but will also use the hollows around tree roots and the burrows created by rodents.


Hedgehog numbers are declining rapidly in the UK and so the hedgehog has been included in the latest UK Biodiversity Action Plan. As a result, many organisations, including BBOWT will be developing plans to save the hedgehog. Suburban gardens are the hedgehog's stronghold and so we encourage wildlife friendly gardening and provide good hedgehog habitats on our nature reserves.

Dormice are protected by law and must not be injured or disturbed. They are included in the UK Biodiversity Action Plan and so BBOWT and other organisations are working to ensure that this species is conserved. This means the provision of special nest boxes and careful management ensuring dormice can move freely around the canopy and can feed on a diverse range of food.

All UK species of bat are protected by law and must not be disturbed, injured or held captive. Even the roosts are protected whether occupied or not. If any work is to be done to a roof, building or hollow tree that bats may be using, it is best to get some expert advice to ensure that bats are protected and the law is not broken. BBOWT strives to create ideal habitat for bats and monitors bat populations on our reserves.

Over one-third of amphibian spawning grounds have been lost, mostly due to agricultural intensification and urban development during the 1960's. BBOWT creates many ponds on nature reserves in an attempt to reverse the decline of our frogs, toads and newts. All amphibians are afforded some protection but the great crested newt and natterjack toad have the highest level of all.

Many UK butterflies have declined as a result of their habitats becoming isolated. This makes them vulnerable to unusual weather such as the flooding last year and this summer. Butterfly Conservation, an organisation dedicated to the conservation of butterflies nationally, reported that several species, including the common blue and small skipper had their lowest ever recorded numbers in 2007.

All the native reptiles in the UK are protected under the Wildlife and Countryside Act 1981 from being killed, injured or sold. Grass snakes are much more common than the adder which has declined due to disturbance and loss of suitable habitat. The adder has been added to the latest UK Biodiversity Action Plan so that plans can be made for its recovery.

How can we help?

To encourage hedgehogs, be lazy and leave some piles of cuttings, leaves or logs in a quiet area for them to use, and try not to disturb such areas in winter. Don't feed them milk as it makes them ill but cat or dog food is fine. Only light a bonfire if you have checked for hedgehogs first. Finally, use slug pellets that are not toxic to mammals if you have to use them at all.

Supporting BBOWT by becoming a member would be a very good way to help these adorable creatures. BBOWT works tirelessly to meet the needs of resident dormice and maintain suitable habitats on farmland. About a decade ago we saved a population of dormice from destruction when the Channel Tunnel was built. This population was released into a BBOWT woodland and has since thrived!

If you are worried that bats are threatened please call BBOWT and we will advise you about what to do. Give us a call also if you find a grounded bat and we can arrange for a trained person from your local Bat Group to collect the bat for rehabilitation and release. If you have a garden or woodland, why not install a bat box? Visit to find out about wildlife gardening.

Garden ponds are an important refuge for amphibians which, far from doing any harm, will in fact be very useful as they eat slugs and snails. It is better if your pond does not have fish as they will eat tadpoles and also the larvae of insects such as dragonflies. A rockery is a great idea too, as it provides safe cracks and crevices for amphibians to hibernate in.

BBOWT aims to link nature reserves and habitats together to create a 'living landscape' so that species like butterflies can move about freely. On reserves such as Foxholes Wood near Shipton-under-Wychwood we look after the purple hairstreak by ensuring its habitat is suitable and maintained. You can help if you have a garden by planting flowers to provide nectar for butterflies. See

Disturbance is a very big threat to adders and it is important that dogs are kept on leads where there are signs requesting this. There are some adder populations on the Cotswold scarp grasslands and dogs may be at risk from being bitten if they harass an adder. But do not worry -adders are rare and only strike as a form of defence, usually preferring to slither away, unless they are cold when they cannot move so quickly.

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