Hazel dormouse

If a development site in the southern parts of England and Wales comprises hedgerows, dense scrub or woodland, then the hazel dormouse (Muscardinus avellanarius) could be present. Without the correct procedures to survey and mitigate for protected and priority species on site, such as the hazel dormouse, planning permission can be delayed or refused. Penalties and even prosecution can apply for developments that do not secure the necessary licences to allow works to go ahead lawfully.

Hazel dormouse: ecology

Early hazel catkins © Staticgirl / Flickr
Early hazel catkins © Staticgirl / Flickr

Testament to their sleepy nature, the name dormouse is derived from the French word ‘dormir’ – meaning to sleep. They’re also commonly referred to as the hazel dormouse, as they’re often found in hazel trees.

Dormice spend much of their life either hibernating, sleeping or in torpor (a state of physical and mental inactivity). Between October and May, dormice hibernate in woven nests beneath the leaf litter on the forest floor or in the base of hedgerows. They can emerge as early as March, and will breed and raise litters later on in the year, spending most of their time in the tree canopy during the summer.

Dormice prefer the successional stage of woody vegetation, particularly well-developed under-storey as a result of woodland management. They can also be found in scrub habitat, old hedgerows and occasionally conifer plantations.

The dormouse has a restricted distribution in the UK, so they could only occur on sites in regions where the species species is present. More information on this can be found on the map on page two of the Peoples Trust for Endangered Species publication ‘State of Britain’s Dormice’ (PDF).

Will hazel dormouse and their habitat impact my development plans?

If proposed work could cause killing, injury or disturbance to either of dormice or damage to their habitats, appropriate mitigation which seeks to avoid these impacts should be devised and implemented, if necessary, under licence from Natural England.

Hazel dormouse: surveys

Hazel dormouse © Matt Wisby
Hazel dormouse during a survey © Matt Wisby

To survey for dormice, two techniques are frequently used. Firstly, where hazel trees are present, a dormouse-gnawed hazelnut search can be carried out all year round. If this survey proves inconclusive, nest tubes can be installed in suitable habitat between April and November and checked monthly for dormouse nests.

Hazel dormouse: legal protection

Over the last 100 years, the hazel dormouse has rapidly declined in range and numbers due to several factors, such as the loss of suitable habitat. As a result, dormice are rare and vulnerable to extinction in Britain.

The hazel dormouse is a Species of Principal Importance for the Conservation of Biodiversity in England (also known as a priority species) and is fully protected under the Conservation of Habitats and Species Regulations 2017, with some addition protection under the Wildlife and Countryside Act 1981 (as amended).

Licensing requirements for hazel dormouse

Because of their full protection under the Habitats Regulations, dormice mitigation on development sites is governed by strict licensing administered by Natural England. Whenever disturbance of dormice or damage to their habitat is likely, a license will be required.

Hazel dormouse: mitigation

Following the completion of surveys, dormouse mitigation may be advised for any development work. This includes habitat creation, habitat enhancements, capture and release of dormice and vegetation clearance under supervision of an ecologist.

The optimal time for above ground vegetation clearance for displacement is November to February; following above ground vegetation clearance, the optimal time for stump and root clearance is between May and September; the optimal time for capture of dormouse is May to mid-June and early July to October. The optimal time for release of captured animals is mid-June to early July.

How we can help

As experts in environmental compliance, we’re experienced in dormouse surveys, licensing requirements and appropriate mitigation works. If you have a project that we can help with, get in touch with us to discuss your needs and the most cost effective and timely options available.

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