The Hazel or Common Dormouse is a nocturnal, arboreal mammal native to Britain. It is distinguished from other small rodents by its black, protruding eyes, thick furry tail and sandy-coloured fur.

Dormice are most commonly distributed in the south of England and are absent from Scotland and Ireland. Their absence from the majority of woods is usually attributed to poor woodland management or historical periods of colder weather. Britain marks the western edge of the range of this species, and consequently its distribution here has always been very patchy.

Dormice prefer woodland edge, overgrown clearings and areas with a high diversity of trees and shrubs, including species producing berries or nuts. There should be sufficient diversity in plant species to ensure a continuous food supply from when they emerge from their nests in late April or May, until their return to hibernation in November. Favoured habitats include coppiced Hazel (Corylus avellana) woodland, and woodland dominated by Oak (Quercus robur) and Holly (Ilex aquifolium), Silver Birch (Betula pendula) or Oak and Ash (Fraxinus excelsior). The optimal habitat is ancient semi-natural woodland that is lightly managed, for example with a long coppice cycle. However, even in such prime habitat, Dormouse densities will only ever reach 8-10 individuals per hectare, and they are usually found at much lower densities. Where local extinctions occur, through poor woodland management or loss of habitat, recolonisation is facilitated if woodland is linked by hedgerows or woodland strips.


The Dormouse is listed on Appendix 3 of the Bonn Convention and on Annex IVa of the European Habitats and Species Directive. The species is also protected under Schedules 5 and 6 of the Wildlife and Countryside Act 1981 and Schedule 2 of the Conservation (Natural Habitats, etc.) Regulations, 1994 (Regulation 38). Together, these make it an offence to:

intentionally kill, injure or take a Dormouse;

possess live or dead animals or any parts thereof;

intentionally or recklessly damage, destroy or obstruct access to any place used for shelter or protection by a Dormouse or to disturb a Dormouse whilst it is using such a place;

sell, offer for sale, possess or transport for the purpose of sale any live or dead animal or part thereof.

When considering planning applications, the authorities are required by law to take account of protected species and the conservation of habitats. A detailed ecological survey is usually required before planning permission can be granted.


There are a number of ways in which Dormice can be surveyed, including the use of nest tubes, nut and nest searches, hair tubes, live traps and nest boxes. Nut searches are best undertaken from December to March, but can be carried out throughout the year. Hair tube/nest tube/nest box surveys are carried out when Dormice are active, i.e. from April to September, but may extend into October if conditions permit.




The Dormouse is a strictly protected species, and all surveys apart from nut searches should be carried out under licence. If development works are to affect Dormice or their habitats a development licence must be obtained from Natural England at least one month in advance of commencement, and appropriate mitigation measures should be put in place. Trees known or suspected to be used as nesting sites by Dormice should be clearly marked and should not be felled. If selective tree lopping, felling and vegetation clearance is required, this should only be undertaken in May and between September and early October (outside of the Dormouse breeding and hibernation seasons). All works should be supervised by a licensed ecologist.