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Forest Research home > Research > Protecting trees > Reducing the impact of non-native or invasive vertebrates to forestry > Management of non-native or invasive vertebrates

Researching management of the edible dormouse (Glis glis)

Edible dormouse - glis glis. Berkhampsted, Hertfordshire, England. 29/05/2009.

The edible dormouse is a grey, tree living rodent about the size of a young grey squirrel and has large eyes as it is only active at night. It feeds on tree buds and seeds, fruit, insects, fungi, carrion and occasionally eggs and nestlings. It hibernates underground for about 7 months of the year (between October and May). Glis glis only breed in good tree flowering years. Although it is protected legally under European law, it is also a pest and many thousands of edible dormice are hunted each year in Europe.

In the UK Glis glis cause damage in woodlands by stripping the bark from the main stem of larch, pine, spruce and beech trees and to properties close to woodlands by gnawing cables, insulation, woodwork and fouling cupboard contents etc. Local Authorities kill Glis under licence in response to the many complaints received from householders. Significant damage has been reported to young beech and larch trees.

(Note, Glis glis is completely different from the native hazel dormouse which is also a protected species).


The British population is due to escapes from a captive population in the Tring area of the Chilterns in 1902 and may number up to 50,000. The distribution of the wild population is mainly bounded by areas that have little woodland; the Oxford plain and the London conurbation. Information from Local Authorities suggests the population is spreading slowly north and south.

Previous research

Research in Europe has focused on species ecology, especially aspects of hibernation, breeding and predation of birds. In the only study in the UK, where animals have been marked for 10 years, information on movements, survival and density has been collected. Population numbers fluctuate considerably between years with breeding dependent largely on tree flowering success.

Research by Forest Research

  • Continued monitoring of the marked Glis in the existing research site, adjacent woods and properties
  • Collation of data on all Glis killed (under licence) to prevent nuisance in properties
  • Visits to confirm presence of Glis reported from apparent remote populations
  • Develop methods for population control under the Defra Non Native Species programme.

Provide us with reports of edible dormice

We are very keen to know of reports of edible dormice in woodlands and properties in woodlands. Please email Robin Gill below or use our website feedback form.


For further information contact:

Dr Robin Gill
Centre for Human and Ecological Sciences
Forest Research
Alice Holt Lodge
Surrey GU10 4LH

Tel: +44 (0) 1420 22255
Fax: +44 (0) 1420 23653