Popular questions about hazel dormice

Frequently asked questions

I love dormice and want to help, how can I get involved?

Thanks for your interest in helping dormice. Because dormice are a protected species, you must have a license to disturb them (which means that boxes cannot be checked or they cannot be handled without a licence). However, other methods like using footprint tunnels or looking for nibbled hazelnuts or natural nests, do not require a license. Take a look at our help pages and about surveying and monitoring.

I think I’ve found a dormouse, what should I do?

If you think you’ve found a dormouse, please fill out our National Dormouse Database (NDD) form. It’s important that you include a photograph so that we can verify your sighting.

If you think you have found evidence of dormice, such as open nibbled hazelnuts, please submit a photograph to enquiries@ptes.org so that they can be verified. Nuts opened by dormice may be confused with those opened by wood mice or bank voles. Use our guide to help you decipher.

I have a woodland/garden, would you like to reintroduce dormice into it?

Due to the resources required, we only oversee one reintroduction each year, into large and connected woods where the dormice will have the best chance at survival. But you can find more information about how you can help dormice here.

I think I have dormice in my woodland/garden. Should I put up some nest boxes to give them a helping hand?

We usually only encourage people to put up dormouse nest boxes in numbers of at least 30 , as we use them for a monitoring tool in wooded areas where we know there is dormouse presence. However, if you are in southern England or Wales (where dormice are present) and want to help dormice with some extra places to nest, you could look at some of the options available with our partner, Wildcare.

But please do not attempt to touch or handle any dormice you may find – it is illegal to do so without a dormouse disturbance license, as they are a protected species under law. If you do have dormouse boxes, but are not licenced, it is illegal to check them in the dormouse active period (between April and November), but it is OK to clear them out when dormice are hibernating on the ground (between December and March). However, if you do find a dormouse in a nest box in winter please leave well alone.

I think I have dormice in my woodland/garden, how can I be sure they’re there?

There are a number of things you can look for to try and assess the likelihood of dormice being present at a site:

• Is the site of interest within the current dormouse range?

• Is the local woodland/hedgerow habitat well connected and continuous?

• Does the site of interest have a diverse range of tree and shrubs? Does the site of interest have a well-developed, and generally continuous, understory?

In rural gardens, dormice are known to feed from bird feeders and so it may be worth setting up a wildlife camera to record what species are visiting your bird feeder at night.

How do I make and/or install a dormouse nest box?

Nest boxes are typically used to monitor populations in relatively high numbers with at least 50 boxes at one site. Dormice live at low population densities, and they are quite rare, so if only a few boxes are put up they are less likely to be used. You should also be aware that it is illegal to check dormouse boxes without a licence from Natural England or Natural Resources Wales as it is illegal to disturb dormouse habitat, which nest boxes potentially become once they have been put up.

It’s November, will dormice have time to get to a good enough weight to survive hibernation?

Young dormice can increase their weight by 1g per day and so, if there is adequate food available, they can reach a hibernation weight relatively quickly. There is also some evidence emerging that young dormice will not go into hibernation until they reach a suitable weight, which could be as late as January.

Why are you bothering to conserve mice, aren’t dormice just vermin?

It’s common to confuse our native hazel dormice to long-tailed field mice (or woodmice – they are two names for the same species) or bank voles, but they are very different. Dormice don’t eat our food; they are woodland animals that feed on flowers, fruit and insects. They do not carry any diseases that can affect people, and they rarely interact with humans; they may come into your garden, if you’re lucky, but they very rarely come into people’s homes. Generally dormice have only one litter of four young a year, and live at very low densities, so their populations will never reach plague proportions. Dormice live in woods and hedgerows and spend the winter in hibernation. We have peacefully coexisted with them for over 12,000 years. They are now endangered and vulnerable to extinction and have disappeared from many regions where they previously lived, which is why they are a UK protected species.

There are two types of dormice in Britain, aren’t there? What are the differences between them?

The non-native Glis glis, also known as Edible or Fat Dormouse, were often eaten as a delicacy during Roman times and were introduced to Britain by Lionel Rothschild on his estate near Tring in Hertfordshire. These dormice are much larger than our native hazel dormice, about the size of a small squirrel, and generally are confined to areas of the Chilterns. They sometimes enter people’s homes and can damage trees and so are sometimes considered a nuisance species.

Hazel dormice are a native, endangered species we’re trying to save,  that are declining in both population size and range extent and exist in low numbers across England and Wales.

We have been working to save hazel dormice in the UK for over 20 years. Find out about our campaigns and how you can help: