Dormouse Surveys

Dormouse Survey Techniques

The hazel dormouse inhabits deciduous woodland, hedgerows and scrub vegetation, often with a high proportion of Hazel. Their distribution in the UK is largely limited to the south of England and Wales. If you plan to develop a site containing suitable habitat and with historic records of dormice nearby, you will likely require a dormouse survey.

Over the past 100 years, this species has declined dramatically in numbers and distribution, at one point being declared extinct in up to 8 counties. Its decline is thought to be the result of a combination of habitat loss and changes in woodland and hedgerow management.

There are a number of techniques commonly used for surveying this species, some being more effective than others. At JCA a combination of two survey techniques are used to determine presence/absence of this species.

The majority of ecological surveys are seasonally constrained. Use our ecology survey calendar to plan your project timetable and factor in any seasonal constraints to project timescales as early as possible to prevent any delays.

Initial Survey

A visual survey is first undertaken, looking for evidence of dormouse activity initially determines whether a site is within the hazel dormouses’s known range and whether the habitat is suitable for supporting hazel dormice. Recent or historic records are used to support the assessment.

Nut Search Survey

This involves a search of suitable habitat, looking for nests and opened hazel nuts. Dormice leave unique marks on shells of hazel nuts, which make them distinguishable from nuts opened by other mammals. This method can be carried out between September and December and positive result in a visual survey may require additional surveys to be carried out.

Tree decay detection

Worried your trees could be experiencing decay? We deploy a variety of decay detection methods

Nesting Survey

Nest boxes and tubes can be used to survey for dormice. Survey techniques involve positioning a large number of boxes and/or tubes (minimum 50 boxes/tubes) within the vegetation on site for several months. Checking is undertaken at monthly intervals to establish an estimated population size. This can determine presence/absence of hazel dormice and provide a population size estimate.

Should Dormice be found at a site, JCA can provide advice on how best to proceed with development.

Dormice and the Law

Hazel dormice are protected under both Conservation (Natural Habitats andc.) Regulations 2017 and the Wildlife and Countryside Act 1981

  • Under these pieces of legislation it is an offence to:
  • Deliberately kill or capture a dormouse.
  • Deliberately disturb a dormouse.
  • Damage or destroy a breeding site or resting place of a dormouse.

Therefore, if dormice are present at a site the appropriate Natural England or Natural Resource Wales Licence must be obtained and mitigation put in place. This mitigation must ensure the continued favourable conservation status of the species.