Dormouse

Dormouse

Status

In Britain the dormouse is largely confined to southern England. The species has declined significantly and has become extinct in seven English counties. This decline has come as a result of changes in woodland management and over grazing of woodland leading to loss of food sources and changes in woodland structure and fragmentation of woodland blocks. Gaps of 100m or less form barriers to dispersal. Small and fragmented populations are prone to extinction.

Ecology

The dormouse is generally nocturnal and arboreal. The species requires woodland and well developed scrub with good linkage between areas of food to allow the animals to travel without coming to the ground. A continuum of food sources is important. Dormouse will feed on a range of berries and nuts including blackberry, hawthorn, hazel, guilder-rose, blackthorn and field maple, it is important that the habitat has a constant supply of food.

The dormouse breeds once or twice a year usually producing four young which are independent in about two months. The nests are usually built from honeysuckle and woven grass and can be located in a wide range of heights from low scrub to high up in the canopy.

The dormouse hibernates between mid to late October until May, depending on the dates of the first and last frosts, at this time they are very susceptible to disturbance.

Protection Under UK Legislation

In England, the dormouse is protected under the Wildlife & Countryside Act and the Conservation (Natural Habitats,&c.) Regulations 1994. Taken together, these legislative instruments make it illegal to carry out the following activities:

Intentionally or deliberately kill, injure or capture dormice;
Deliberately disturb dormice (whether in a nest or not); and
Damage, or destroy dormouse breeding sites or resting places.

Any activity that would result in a contravention of the above legislation would require a Natural England licence to avoid committing an offence.

Survey Methods

Dormouse surveys must be carried out by a licenced surveyor. ECOSA surveyors hold current Natural England dormouse licences for England and Wales. Dormouse surveys consist of two elements:

Box and Tube Surveys

The survey involves the erection of boxes or tubes, ideally in March or April within areas of woodland and scrub. Dormice utilise the boxes and tubes for nesting and shelter. The survying of the boxes and tubes on a regular basis between May and October is an effective way to record the presence of these animals.

Nut Search Surveys

Dormice leave distinctive feeding evidence on one of their favourite food sources, hazel nuts. Nuts located beneath hazel trees are surveyed for evidence of feeding activity. This is most effective in September to November when fallen nuts are at their freshest and feeding evidence left by the species is still evident. Later, nuts may become dispersed with worn feeding evidence.

Survey Timing

Dormouse boxes and tubes are best erected in March and April before the species emerges from hibernation. Inspection of boxes and tubes then must continue (ideally at fortnightly intervals) throughout the summer until around mid-October, when the species enters hibernation. Nut searches can be carried out throughout the year but the results are most reliable when carried out between September to November.

Mitigation

If Dormouse habitat loss is unavoidable as a result of a development, mitigation will involve the replanting of habitat at a similar or greater extent to that lost. Perhaps of greatest consideration is the maintenance of linkage between areas of suitable habitat. This involves the maintenance of hedgerows, scrub and woodland strips linking more extensive areas of woodland or mature scrub that function as breeding areas. Where dormouse habitat is to be lost it will usually be necessary to translocate animals away from this area, to permanently retained areas. Removal of dormouse habitat is generally only possible between May and October when the species is active.

Links

Biodiversity Action Plan

The Mammal Society

Disclaimer

Although we have taken great care to ensure that our information and advice is correct, we cannot accept any responsibility for any incorrect information, loss or damage incurred arising from the use of the information published on our web site. For further advice, detailed surveys and quotations please contact ECOSA.

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