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Cornish Red Data (2009)

The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.

Muscardinus avellanarius - Hazel Dormouse

Range & Status

Mainly central Europe from France to the Urals and marginally into Turkey. Absent from Iberia and most of Scandinavia (Harris & Yalden, 2008). In England, Hazel Dormouse is widespread with a somewhat patchy distribution south of a line from London to Gloucester and extending into the Welsh Borders. There are scattered populations in Suffolk and Northamptonshire with three isolated populations known in Cumbria and Northumberland. Hazel Dormouse is widespread in south-east Wales but absent from Scotland and Ireland (Harris & Yalden, 2008). A total pre-breeding population estimate of 500,000 for England and Wales has been calculated (Harris et al ., 1995).

Regional Distribution

The current distribution map from ERCCIS shows most known sites to be in the southeast quarter of Cornwall, with a cluster in the extreme north-east and a single 1km x 1km square on the Lizard Peninsula. There is a particularly notable small population of Hazel Dormouse which, amazingly, is located in a fairly wide scrub-dominated central reservation of the A30 dual-carriageway, with two lanes of traffic on either side of the colony. There are presently seven National Dormouse Monitoring sites, in Cornwall, with a further two sites planned. In addition, in recent years, an increasing number of new sites have been found in Cornwall. In 1993 English Nature launched ' The Great Nut Hunt' , an appeal for the public to send in hazelnuts opened by small mammals: the feeding evidence on hazelnuts opened by Hazel Dormouse is distinctive, and presence of Hazel

Dormouse using this method therefore is confirmed. Devon came out as the top county in the survey, with most positive records. In Cornwall, the survey produced eleven positive identifications with about twenty-six negatives, but the northern two-thirds of the western half of Cornwall was not surveyed (English Nature, 1994).

Habitat & Ecology

Found in deciduous woodland with plenty of secondary growth and scrub such as Bramble Rubus fruticosus agg., in particular where seed-producing trees and shrubs such as Beech Fagus sylvatica , Hazel and Sweet Chestnut Castanea sativa are available to provide a food source. However, in recent years it has become evident that although important, these species are not essential. Hazel Dormouse is also found in species-rich hedgerows, coppice and damp woodlands, and in marshy places and reed-beds with Alder Alnus glutinosa . Arboreal pathways formed by overgrown coppice and climbing plants, such

as Honeysuckle Lonicera periclymenum , can be important. Coniferous plantations are sometimes occupied, particularly where deciduous trees and shrubs are present (Harris & Yalden, 2008) and in Cornwall and Devon they have been found occasionally in gorsedominated coastal scrub (National Trust Wardens, pers. comm.). Hazel Dormouse is a specialist feeder, which requires a succession of fruiting trees and shrubs. Food includes flowers, pollen, fruits, nuts and insects. The Hazel Dormouse readily takes to custom-made nest-boxes, and produces only a small number of young over a number of years.


Loss and fragmentation of habitat are the main threats to Hazel Dormouse, particularly the loss of ancient semi-natural woodland and other habitats. The destruction of aerial pathways, clear-felling, short coppice rotations and neglect are all examples of poor woodland management activities which threaten this species (Harris et al ., 1995). The Hazel Dormouse is on the edge of its range in Britain probably due to climate factors. Given the uncertainties of the British climate a succession of bad summers could reduce successful breeding over several years leading to local extinctions (Harris et al ., 1995).


There is a wealth of written information available on the conservation of Hazel Dormouse, e.g. Bright and Morris (1990, 1992, and 1993) and Morris (1993). Natural England has produced the Dormouse Conservation Handbook (Bright, Morris & Mitchell-Jones, 2006). The Hazel Dormouse is part of the Species Recovery Programme (managed by Natural England). A South West pilot project in 2002/2003 put out Hazel Dormouse monitoring tubes at 13 sites, producing two new records, and several training days have been organised by CMG and CWT. Dormouse box building days have also been held in recent years. Research on this species in Cornwall, starting in 2008, w

Click here to see Aphotoflora images by David Fenwick


I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.

The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.