What we offer

Greenlight Environmental Consultancy offers multiple services with respect to dormouse surveys, including:

  • Preliminary Ecological Appraisals (“PEA”) – An initial site assessment to identify habitats present on site that may support protected species. This includes a site visit and a desktop assessment. A PEA is typically required as a first step to address the ecological aspects of a planning application. The PEA would recommend if further dormouse surveys are necessary, and appropriate mitigation and enhancements for the proposed development.
  • Visual searches for signs of presence – A search for gnawed hazel nuts to determine the presence of dormice on a site. 
  • Nest tube surveys – Surveys using nest tubes to confirm the absence/presence of dormice in a woodland. These dormouse surveys would help to determine the size of the population present and inform mitigation measures.
  • European Protected Species (“EPS”) Mitigation Licences – A licence issued by Natural England under the Conservation of Species and
    Habitats Regulations 2010 (as amended) to capture or disturb individual dormice and to obstruct, modify, or destroy their breeding/resting places
  • Translocation works – Individual dormice are caught and translocated to a suitable receptor site, undertaken under an EPS mitigation licence, to avoid killing or injuring individual dormice.
  • Overseeing works (including toolbox talks) – A watching brief during construction works, often undertaken under an EPS mitigation licence, to avoid killing or injuring individual dormice.



The hazel dormouse Muscardinus avellanarius has declined in both numbers and distribution by at least 50% over the last century and continues to deteriorate. They are a flagship species, as their conservation has an ‘umbrella effect’ – protecting and conserving other species in the same habitat (Bright et al. 2006).

The hazel dormouse is an agile climber and is predominantly nocturnal. They build nests in summer from grasses, stripped honeysuckle bark and fresh leaves. During winter months, dormice hibernate on the ground, under logs, leaves, at the base of trees or within grass tussocks. Their name is thought to derive from the French word ‘dormir’ meaning ‘to sleep’, with individuals regularly being recorded hibernating for seven months of the year.


Hazel dormice are protected under UK and European Union (“EU”) laws, including:

Under these legislations dormice are protected from:

  • Capturing, killing, injuring and disturbing;
  • Damaging or destroying breeding/resting places;
  • Obstructing access to resting places; and
  • Possessing, advertising for sale, selling or transporting for sale, live or dead (part or derivative).

For all development proposals which have the potential to impact on local biodiversity, Local Planning Authorities (“LPA”) require sufficient information to make informed decisions that wildlife can be protected from injury or disturbance during the development. They often require a Preliminary Ecological Appraisal (“PEA”), and further dormouse surveys if the species is likely to be present.

If hazel dormice are present on a site for development, it is likely that a European protected species (“EPS”) mitigation license and an appropriate mitigation strategy will be required in order to proceed with the works.


Hazel dormice are heavily associated with long-rotation hazel coppiced woodlands (12-20 year rotations), preferring areas near honeysuckle, hazel, oak and bramble. However, they occupy a variety of habitats including hedgerows, woodland, scrub, etc. Open areas can act as a barrier against dispersal, as dormice are highly arboreal and avoid descending to the ground. Areas connected via the canopy offer some form of dispersion.

In thriving populations, individuals are likely to move into surrounding regions where the habitat is less favourable. Therefore, their presence should be assumed in any woody habitat, especially in the south of England, within their range (Berks, Bucks & Oxon Wildlife Trust 2015; Bright et al. 2006).



Dormouse surveys are highly seasonal and although an initial assessment can be conducted at any time of year, presence/absence surveys can only be conducted between April and November. Please note that nest tubes should be installed in March, in preparation for the beginning of dormouse surveys.

Hazel Dormouse surveys (timings)

Mitigation and enhancements

In a situation where negative impacts on hazel dormice cannot be avoided, mitigation measures such as the following can be used to reduce these impacts. If only a relatively small part of a hedgerow or woodland strip is to be removed, and that the remaining habitat is linked to larger dormouse habitat, dormice can be persuaded to leave the area by progressively clearing narrow strips of habitat. Another mitigation strategy may be to create habitat bridges for dormice. If no other mitigation designs are achievable, dormice may also be translocated to a suitable receptor site. Compensation and enhancement measures may include creating new dormouse habitat (hedgerow, scrub, woodland or boxes), and improving retained habitat (through thinning, coppicing or new planting).


The Dormouse Site



Berks, Bucks & Oxon Wildlife Trust. (2015), Common dormouse, Factsheet No. 9. The Wildlife Trust – Information Service, Oxford.

Bright, P.W., Morris, P.A., Mitchell-Jones, A. (2006), Dormouse conservation handbook 2nd edition. English Nature, Peterborough.