How to help endangered dormice (wake up to the crisis)
Hazel dormice are among England’s most vulnerable small mammals. These tiny, golden-brown animals spend much of the year hibernating, but their survival depends on what happens during the months they are awake: finding enough food, raising young and moving safely through connected habitats.
The good news is that farmers, landowners, planners, volunteers and householders can all help. Protecting hedgerows, restoring woodland and planting native hazel can give dormice the food and shelter they need. Just as importantly, new development and road projects can be planned to keep habitats connected.
Why are hazel dormice endangered?
Hazel dormice are found in parts of England and Wales, but their range and numbers have declined. The People’s Trust for Endangered Species (PTES) reports a substantial long-term decline in the UK population. A commonly cited estimate is a fall of around 70% since 2000, although the exact figure depends on the period and data used. It is safest to describe the decline as severe.
Habitat loss and fragmentation are major pressures. Woodland clearance, neglected or poorly managed hedgerows, intensive farming and development can remove the places dormice feed and nest. Roads, fences and buildings divide habitats, so animals can’t move between woodland and hedgerows.
Climate change adds further uncertainty. Warmer, wetter winters may affect hibernation, while changing seasons can alter the timing and availability of flowers, insects, berries and nuts. Dormice need food at different times of year to build up energy before hibernation and to support reproduction.
Because dormice reproduce relatively slowly, local populations may take time to recover. Females commonly have one litter in a year, though breeding patterns vary with conditions and a second litter can sometimes occur.
Protecting habitat is therefore essential: a population cannot thrive if it has nowhere safe to feed, nest and move.
What do dormice look like?
Hazel dormice are small, usually weighing only a few tens of grams. They have soft golden or reddish-brown fur, a pale underside, rounded ears and notably large, dark eyes. Their long, furry tails help distinguish them from mice and voles.
They are mostly nocturnal and spend much of their time in trees and shrubs. Dormice are capable climbers, using branches, brambles and hedges to travel through vegetation. They may come down to the ground, particularly when moving between habitats or building a winter nest.
Dormice are not long-distance leapers. They rely on branches and dense vegetation to move around, rather than jumping across wide gaps. A break in a hedge or a cleared strip between woodland patches can therefore be a serious obstacle for a very small animal.
What do dormice eat?
Dormice change their diet through the year as different foods become available. They eat flowers, pollen, nectar, insects, fruit and nuts. Their diet can include caterpillars and aphids, as well as other small invertebrates. Bramble and honeysuckle are valuable sources of flowers and berries, though the exact foods eaten depend on the season and what is available locally.
Hazelnuts are especially important in autumn. They provide energy-rich food that helps dormice build up reserves before hibernation.
Hazel trees also offer useful branches and cover, and dormice may build nests in shrubs or trees nearby.
A varied habitat matters more than a single food plant. A woodland edge with hazel, bramble, honeysuckle, flowering shrubs and a healthy supply of insects can provide food across more of the year.
How can you identify dormouse-nibbled hazelnuts?
A hazelnut with a small, neat round hole may have been opened by a dormouse. Dormice often leave a distinctive pattern: a smooth, round opening with fine tooth marks running around the inside edge, broadly following the curve of the shell.
Other animals, including wood mice and bank voles, also eat hazelnuts, but their marks tend to look different. Wood mice often leave rougher, more jagged edges, while squirrels may split or break the shell more extensively. A single nut is not always enough for a certain identification, so look for several examples and compare them with a reliable dormouse-nut identification guide.
Dormice and their nests are legally protected in England. Do not handle an animal, disturb a nest or carry out work that could affect dormice without checking the relevant rules and seeking expert advice.
Why are hedgerows so important?
Hedgerows are more than boundaries. For dormice, a thick, species-rich hedge can provide food, nesting material, shelter and a route between woodland patches. Bramble, honeysuckle, hazel and other native shrubs offer a changing supply of flowers, insects and fruit.
A connected network of hedges can help dormice move through the landscape without crossing open fields or roads. Gaps, hard pruning and the removal of mature hedges can break that network. Where a hedge has become thin or fragmented, restoring it with native species can make it more useful over time.
Hedgerows also benefit many other species, including birds, bats, pollinating insects and hedgehogs. They can reduce soil erosion, store carbon and help wildlife move as the climate changes. Keeping them healthy is a practical way to support biodiversity across farmland and towns.
Some hedges (including yew, privet, laurel, buckthorn and holly) are unsafe near grazing horses or livestock.
How can volunteers and farmers plant hazel?
Planting native hazel can improve habitat where it is appropriate, especially as part of a wider plan to restore woodland edges and hedgerows. Hazel should not be planted in isolation and assumed to solve the problem: dormice need connected, varied cover and suitable habitat around it.
Volunteers and landowners can help by:
- Planting native hazel as part of mixed hedgerows or woodland edges.
- Include native shrubs and trees for flowers, berries, insects and cover.
- Filling gaps in existing hedges to improve connectivity.
- Protecting young plants from browsing and maintain until established.
- Avoiding work during sensitive nesting and breeding periods, and checking for legal restrictions before managing potential dormouse habitat.
- Working with local wildlife groups, ecologists or conservation organisations to choose suitable sites and planting methods.
Hazel is a valuable food source, but dormice also need seasonal foods. A diverse hedge is generally more useful than a single-species planting.
How can nature-friendly farmers protect dormice?
Farmers can make a major difference because hedgerows and small woodlands across farmland form much of the landscape dormice use. Nature-friendly farming does not mean stopping food production. It means managing land so that wildlife habitat can exist alongside productive fields.
Helpful measures include retaining mature hedges, restoring gaps and allowing hedges to grow thick enough to provide cover. Rotational hedge cutting—rather than cutting every hedge hard in the same year—can leave some sections to flower and fruit. Cutting at appropriate times also reduces the risk of disturbing nests.
Other useful actions include:
- Keeping or creating small areas of scrub and woodland edge.
- Planting native trees and shrubs where they connect existing habitat.
- Maintaining uncultivated margins and flowering areas that support insects.
- Avoiding unnecessary clearance of bramble and other valuable undergrowth.
- Managing grazing so young hedges and woodland regeneration can establish.
- Using wildlife surveys and farm conservation advice to guide decisions.
A patchwork of hedges, trees, scrub and flowering margins can support dormice while also benefiting pollinators, birds and other mammals.
How to build homes, without harming wildlife
Housing and infrastructure are needed, but development should not treat wildlife habitat as an afterthought. Roads, housing estates and boundary fences can remove hedges or leave woodland isolated. When several small losses accumulate, the result can be a landscape that is difficult for dormice to cross.
Planners and developers should identify important habitat early, before designs are fixed. Ecological surveys can help establish whether dormice may be present and what measures are needed. Avoiding damage is preferable to trying to replace a mature hedge or woodland after it has been lost.
Good planning can include retaining and strengthening hedgerows, leaving connected green corridors, protecting woodland edges and providing suitable crossings where needed. New planting should link to existing habitat.
Affordable housing and wildlife protection are not mutually exclusive. The challenge is to plan homes, roads and green space together, with evidence-based safeguards. Weakening protections or rushing development without proper ecological assessment risks damaging wildlife habitats.
Can dormouse bridges help them cross roads?
Wildlife bridges and rope bridges can help animals cross roads safely where routes have been severed. PTES has worked on dormouse-friendly crossing solutions, including bridges that can be installed as standalone structures or incorporated into an overpass.
The design and location matter. A bridge needs to connect with suitable vegetation on both sides, and it must be maintained. It is not a substitute for protecting a hedge or woodland in the first place, but it can help reduce the barrier created by traffic in locations where a crossing is needed.
Helping dormice wake up to a safer future
Dormice need more than one food tree or a nest box. They need a living network of woodland, hedgerows and scrub, with food available across the seasons and safe routes between habitats. Hazel is important, especially for its autumn nuts, but bramble, honeysuckle, flowers, insects and other native plants all contribute.
Farmers can restore hedges and manage them thoughtfully. Volunteers can plant and care for native shrubs. Planners can design development around connected habitat, and communities can support local conservation work. These actions will not reverse the decline overnight, but together they can give dormice a better chance to feed, breed, hibernate and return year after year.
This free Dormouse Conservation Handbook is an ideal read for farmers and town planners. Reconnecting these green corridors helps dormice to find food, grow numbers and keep safe from predators.
