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Dormouse Surveys

The dormouse is a strictly protected species

The dormouse

The hazel dormouse (Muscardinus avellanarius) is reputedly the sleepiest of the British mammals. They are a strictly nocturnal species found mainly in southern counties of England and Eastern counties of Wales. There are some scattered locations in West Wales. Hazel dormice are predominantly found in deciduous woodlands and hedgerows but despite their name, they are not exclusively associated with Hazel trees (Corylus avellana) for their habitat and food source. The ideal habitat would be a semi-natural ancient woodland with mixed hazel coppice.

Their favoured food source is hazel nuts, but will eat flowers, pollen, nuts and insects. A key indicator of the presence of dormice in a woodland or hedgerow is the discarded shell of a hazel nut. Whilst other mammals will leave discarded shells after feeding, the key identifier for a dormouse is the neatly nibbled round hole in the top of the shell. The hole will have a smooth inner rim with tooth marks that are angled around the hole.

IS - dormouse

Where to find dormice 

Being nocturnal these animals are rarely seen, spending most daylight hours asleep, coming out at night to feed. They have large black eyes with a brown- gingery furry coat and a fluffy tail. During the winter months (October-April) they will come down from the trees and hedgerows to hibernate in tightly woven nests the size of a tennis ball on the ground, in leaf litter and around tree roots.

Dormice build nests in dense, thorny scrub, in hedgerows and in holes in trees. Their nests are woven structures of grass and leaves and found within low growing shrubs measuring between 100-150mm in diameter. Their typical home range is approximately 50 metres.

Protected under law

Dormice are strictly protected by law and may not be intentionally killed, injured or disturbed in their nests, collected, trapped or sold except under licence. 

They are protected in the UK under the Wildlife and Countryside Act, 1981. Priority Species under the UK Post-2010 Biodiversity Framework. Listed as a European Protected Species under Annex IV of the European Habitats Directive. Dormice are afforded this protection as their population numbers and distributional range has halved in the past 100 years.


Dormouse surveys

Dormouse surveys are undertaken by licensed and experienced ecologists to establish their likely absence or presence using different techniques depending on the site being surveyed and time of year. There are restricted periods when certain surveys are possible. 

Dormouse survey techniques range from simple nut searches and nest tube surveys, through to nest box checks and footprint tunnels. The objective is to confirm how dormouse uses the site and make an estimate on the population size, so proportionate mitigation or compensation measures can be implemented under a mitigation licence.

Frequently Asked Questions

Download our free survey calendar to ensure that surveys are scheduled to form part of your timescale.