Hibernation

Our Treasurer Alistair Beswick fills us in on the wonders of hibernation, and what everyone can do to help hibernating creatures in our Parish.

UK Wildlife and hibernation -  and what we can do to help

Hibernation is a crucial survival strategy for certain UK species, allowing them to endure the cold winter months when food is scarce. Hibernation is far more complex than many people realise, and not simply a long sleep for most species.

The Main Mammalian Hibernators

In the UK, only three mammal species are considered "true hibernators," meaning they enter a ‘torpor’ from which they wake as necessary. Many other animals, like reptiles and amphibians, enter a similar state called brumation or shorter periods of torpor.

European Hedgehog

Photo credit: Vera Buhl, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons

Typical Hibernation Window: November to mid-March/April

Hedgehogs must reach a minimum weight (at least 500g) by late autumn to have a good chance of surviving winter. They are triggered by low temperatures and food scarcity (as slugs and insects disappear).

They build a secure nest called a hibernaculum in compost heaps, under sheds, or in log piles. Their heart rate drops from about 190 to just 20 beats per minute. They do periodically wake up during mild spells to move location or feed.

Hazel Dormouse

Photo credit: Zoë Helene Kindermann, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons

Typical Hibernation Window: October/November to April/May

Although we don't have any dormice living in Chapel, these delightful creatures were recently reintroduced to Calke Abbey near Derby.

The dormouse is one of the champion sleepers, sometimes spending up to three-quarters of the year dormant. Their hibernation is often triggered when the ambient temperature drops below 15C and daylight hours become very short.

They weave a spherical nest near or on the ground, curl up tight, and live off body fat reserves, losing up to 30% of their body weight by spring.

Photo credit: Barracuda1983, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons

All Bat Species

Typical Hibernation Window: November/December to March/April

Bats hibernate due to the lack of flying insects, their primary food source, which vanishes when temperatures drop and daylight is minimal. They seek stable, cool environments like caves, tunnels, or hollow trees, where the temperature remains steady and above freezing (ideally around 2C).

They drastically slow their breathing, sometimes to only a few breaths per minute.

Brumation in UK Reptiles and Amphibians

Unlike true hibernation, reptiles and amphibians are ectotherms, meaning their body temperature is regulated by the environment. Their winter dormancy is called brumation.

They typically begin brumation earlier than mammals, often in October, in response to declining daytime temperatures and lack of sun warmth.

Reptiles (e.g., Grass Snakes, Adders) seek dry, frost-free refuges such as rock crevices, leaf litter, or old rodent burrows.

Amphibians (e.g., Frogs, Toads, Newts) hibernate on land in damp, sheltered spots like compost heaps or under log piles. Only a minority of frogs choose to spend winter submerged in the mud at the bottom of ponds.

Impact of Climate Change

Unseasonably warm weather, an increasing reality in the UK, poses a major risk to hibernating species. Warmer spells can cause animals to wake up mid-winter, consuming vital fat reserves. If they wake up when there is still no food available, they may starve before spring truly arrives. Similarly, a mild autumn can delay hibernation, leaving smaller, younger animals vulnerable if an abrupt cold snap suddenly hits.

How can humans help our native creatures to survive the winter?

• Provide Safe Shelter and Habitats 🪵🍂

  Create "wild corners". Leave piles of leaves, logs, and brushwood in undisturbed areas of your garden, which offer natural insulation and shelter for hedgehogs, amphibians (frogs, toads, newts), and numerous insects like ladybirds and solitary bees.

• Install hedgerows 🌿

  If you have space, consider growing a hedge rather than putting in a fence. Hedgerows from native species are better for wildlife, but any hedge will provide shelter.

• Plant berry- and seed-bearing native plants 🫐

  Grow native shrubs and trees such as hawthorn, holly, and rowan, which provide berries well into winter. Leave seed heads on plants like sunflowers and teasel standing until spring to provide food for birds.

• Install ready-made homes 🏚️

  Consider putting up a purpose-built hedgehog house or a bug hotel in a sheltered, frost-free location to provide secure overwintering spots.

• Manage ponds carefully ❄️

  If you have a pond, remove excess decaying leaves in autumn to prevent toxic gas buildup under ice. In freezing weather, float a ball on the surface to maintain an oxygen hole, or use a hot pan to melt a small area; never use force or boiling water to break the ice, as this can harm aquatic life. Ensure there is a ramp or shallow edge for animals to exit safely.

• Clean nest boxes🐦‍⬛

  Clean out existing bird nest boxes in autumn to offer valuable, dry shelter for small birds to roost in during cold nights.

• Minimize ground disturbance 🌱

  Avoid digging or heavy clearing in garden beds where ground-nesting bees and other invertebrates may be hibernating.

• Offer Food and Water 🍽️💧

  Provide autumn food sources, to help animals like hedgehogs build up vital fat reserves. This can include leaving out high-protein meaty dog or cat food. Ensure a reliable source of fresh, clean, and ice-free water is available daily for active mammals and birds.

• Avoid harmful foods and chemicals ⚠️

• Never leave out milk or bread for hedgehogs. Refrain from using pesticides and herbicides in your garden, which can reduce the insect populations that many species rely on for food.

• Be cautious with garden tidying and bonfires 🔥

  Before lighting a bonfire or clearing large piles of leaves, logs, or brush, check carefully for hibernating animals and move any found to a new, safe location.

• Create a "hedgehog highway" 🦔

  Cut a small gap (around 12cm x 12cm) in the bottom of your fence to allow hedgehogs to move between gardens to find enough food and shelter.

• Avoid disturbing hibernating animals 😴

  If you accidentally uncover a hibernating animal, cover it back up gently and leave it undisturbed in the same location.