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Dormouse scoping survey
An initial dormouse scoping survey is generally carried out as part of a Preliminary Ecological Appraisal. A desk top study is carried out to obtain any records of dormouse close to site, with a field survey undertaken to ascertain whether habitats upon a site or in the immediate surrounding area have the potential to support dormouse. This includes recording habitat structure and connectivity and the availability of flowering and berry producing shrubs and trees.
This scoping survey can be carried out at any time of year, however further surveys may be required to identify presence/absence and key habitat areas or where significant impacts from a proposed development or an activity are anticipated.
Nut and nest search
The most efficient method to establish dormouse presence at a site is to look for gnawed hazelnuts beneath the canopy of hazel scrub, a favoured food of this species. Dormouse leave a characteristic smooth round opening upon the nut shell in comparison to other rodents and birds. A systematic ground search for gnawed hazel nuts is therefore a relatively quick method of identifying dormouse presence on or adjacent a site.
Where no hazel is present, other survey methods can be used including a search for summer nests. Dormice will build several of these nests, usually in dense vegetation during the active season, constructed out of stripped bark or grass and surrounded by leaves. The nests are abandoned when dormice go into hibernation and usually disintegrate over winter.
Nest tubes and footprint tunnels
The use of nest tubes is a long recognised survey methodology for identifying the presence of dormice, and is especially useful where hazel is absent. The tubes consist of a plastic tunnel which is sealed at one end; these are then fixed and suspended beneath horizontal tree limbs where they resemble a hollow branch. Nest tubes are set out in suitable dormouse habitat and left in place for several months where they are checked once or twice a month for the presence or evidence of dormice.
Dormouse footprint tunnels are similar in design to nest tubes and may prove more successful at identifying dormouse presence than nest tubes. These footprint tunnels are suspended beneath horizontal tree and shrub branches but are open-ended allowing the free movement of animals. A harmless ink medium allows footprints to be imprinted upon card inside the tube. Tunnels are left in place for several months and checked and re-inked every two weeks.
Timing of surveys
- Initial scoping surveys for dormouse can be undertaken at any time of the year as part of a Preliminary Ecological Appraisal;
- Nut searches (where hazel is present) – this survey approach is best carried out between mid-August and December;
- Nest searches are best undertaken in late autumn/early winter, between October and the end of December, when leaves start to fall and nests become more visible in dense vegetation;
- Nest tubes and footprint tunnels should be placed in suitable dormouse habitat on site by March to cover the main activity period for this species (April to November).
Mitigation and licencing
When surveys are complete, a full Ecological Impact Assessment of a proposed development or activity can be made and an appropriate and practical dormouse mitigation strategy can be devised and agreed. Even if dormouse are found it may be possible for a development or activity to proceed following a precautionary working methodology to prevent disturbance of dormouse or damage/destruction of their habitat. For example re-designing proposals could minimise or avoid areas where dormouse are present.
If impacts are unavoidable then a European Protected Species Licence (EPSL) from Natural England may be needed for a project to proceed. The content of the licence will vary on a site by site basis but usually includes sensitive timing of works to avoid the breeding or hibernation seasons. If there is sufficient adjoining habitat then it may be possible to encourage dormouse out of an area by manipulating the vegetation in stages. As a last resort it may be necessary to translocate dormouse out of the working area in advance of the works.
Usually there is a need to provide new habitat or enhancement of existing habitat as part of a planning application or a EPSL application.
Legislation
Dormice are protected under the Wildlife and Countryside Act (WCA) 1981 (as amended) and the Conservation of Habitats and Species Regulations 2017.
This makes it an offence to kill, injure or disturb a dormouse, or to damage, destroy, prohibit or obstruct access to places of refuge.Under the legislation it is also an offence to cause disturbance which is likely to impair a dormouse’s ability to survive, breed, hibernate and/or migrate.
Note
The above information is based on standard guidelines and current UK legislation. Every site is unique so please contact a Torc Ecology consultant who will advise on the best survey approach in relation to the project requirements.
Facts about dormouse!
The dormouse is a nocturnal animal that lives in a variety of habitats but is traditionally most associated with well-structured deciduous woodland, including coppiced woodland, dense old hedgerows and scrub.
The dormouse spends much of its time climbing and feeding amongst branches, rarely descending to the ground apart from during the winter months where it will hibernate at or below ground level in leaf litter on forest floors, at the base of hedgerows, or even in wall cavities between October to April/May.
This distinctive mammal with its orange-brown coat, large black eyes and thick furry tail requires a variety of foods throughout the year while they are active. In spring they will feed on the flowers of oak, hawthorn, sycamore and willow, and as the season progresses move onto later flowering shrubs such as honeysuckle and bramble. During the summer they take advantage of caterpillars, aphids and wasp galls and then fatten up for hibernation on fruits and berries, such as blackberries and hazelnuts.
