Ecological survey calendar › Hazel dormice
When to survey for hazel dormice in Wales and England
Updated November 2026. Includes the 2025 Hazel Dormouse Conservation and Mitigation Handbooks and Natural Resources Wales's 2026 dormouse good practice guide.
A nest tube survey to show likely absence of hazel dormice runs for a full season, from April or May to November, so tubes need to be up early. Footprint tunnels are an alternative, run for three consecutive months between May and October. Clearance of dormouse habitat is done in two stages and avoids June to August, when females have young.
Survey windows, sensitive periods and works timing
| Activity | Type | When | Notes |
|---|---|---|---|
| Nest tube surveys | Survey | mid-Apr to Nov | 50 tubes in scrub, hedgerow and dense coppice, or 100 in high canopy woodland or poorer habitat, checked monthly for a full season (April or May to November). Adding tubes does not shorten the survey. |
| Footprint tunnel surveys | Survey | May to Oct | 50 tunnels checked and re-inked every two weeks for three consecutive months between May and October, put up two weeks before the survey starts. |
| Nut searches | Survey | Sep to Dec | Search for hazelnuts opened by dormice after nut fall. Shows presence only. |
| Hibernation | Sensitive period | Nov to Apr | Dormice hibernate on or near the ground and may not emerge until April or May. NRW asks for no ground preparation near good habitat from 1 November to 31 March. |
| Breeding season (dependent young) | Sensitive period | Jun to mid-Sep | No felling or scrub clearance from 1 June to 31 August, and ideally not in early September. |
| Above-ground cutting by hand (licensed) | Works window | Nov to Feb | First stage of a two-stage clearance. Guidance allows November to March; ending in February avoids the bird nesting season. Stumps and roots stay until dormice are active again. |
| Ground clearance (licensed) | Works window | May; mid-Sep to Oct | Second stage, once dormice are active: May, before females have young, or from mid-September. Check for nesting birds. |
Optimal survey Possible, not ideal Sensitive period Works window
Timing depends on the site, the weather in a given year and what the planning authority and licensing body need. Upland and northern sites can run later. See every species group side by side on the ecological survey calendar.
About hazel dormice
A nocturnal, tree-dwelling mammal of woodland, scrub and species-rich hedgerows. It hibernates in nests on or near the ground from late autumn to spring and is rarely seen, so surveys rely on nest tubes and gnawed hazelnuts.
Legal protection
European protected species under the Conservation of Habitats and Species Regulations 2017.
Licensing
Wales: Vegetation removal in occupied habitat needs a European protected species licence from Natural Resources Wales.
England: Vegetation removal in occupied habitat needs a Natural England licence.
Practical tips
- Plan dormouse surveys early. A nest tube survey to show likely absence runs for a full season, so tubes need to be up by April or May.
- Design mitigation using the Hazel Dormouse Mitigation Handbook (Wells, Chanin and Gubert, 2025).
Common questions
When is dormouse survey season?
Nest tubes are checked monthly from April or May to November. Footprint tunnels are checked every two weeks for three consecutive months between May and October (Hazel Dormouse Conservation and Mitigation Handbooks, 2025).
How many nest tubes are needed?
50 tubes in scrub, hedgerow and dense coppice, or 100 in high canopy woodland or poorer habitat. Adding more tubes no longer shortens the survey.
When can dormouse habitat be cleared?
In two stages under licence. Above-ground vegetation is cut by hand in winter while dormice hibernate, and stumps and roots are removed once they are active again, in May or from mid-September. Natural Resources Wales advises no felling or scrub clearance from 1 June to 31 August.
Is a nut search enough?
A nut search can show that dormice are present, but it cannot show they are absent. A standard nest tube or footprint tunnel survey is needed for that.
Need a survey or advice on timing? Ecoleg's licensed ecologists programme surveys across Wales and England so the right work happens in the right season. Call 07356 123706.
Request a quoteSee the full calendarSources
- Bullion, S., Wolton, R. and White, I. (2025) Hazel Dormouse Conservation Handbook, 3rd edn. Mammal Society.
- Wells, D., Chanin, P. and Gubert, L. (2025) Hazel Dormouse Mitigation Handbook. Mammal Society.
- People's Trust for Endangered Species, hazel dormouse nest tube and footprint tunnel survey guidance (accessed November 2026).
- Natural Resources Wales (2026) Good Practice Guide: protecting hazel dormice during woodland management and forestry operations, version 1.0.
- Common professional practice; confirm for each site.
Updated November 2026. General guidance only: confirm timing for your site with a suitably qualified ecologist.