Declined in the second half of the 19th century and apparently died out early in the 20th century. Jourdain (1905) said “…appears to have been tolerably numerous in former times, at the present day it is exceedingly local and scarce except in one or two places”. He quotes an 1862 source as saying it was formerly abundant, especially in large woods of south Derbyshire but becoming annually more rare. Jourdain listed Lea Valley, Alderwasley, High Tor woods and Lea Wood, Derwent, as localities where it still occurred. There is a late 19th century record from the Goyt Valley. A dubious record from Elvaston in July 1965 (Middleton 1969) has not been confirmed.

No evidence of its presence in the county was found on the two Great Nut Hunts (national dormouse surveys) of 1993 and 2002, but small populations could conceivably survive in the south. The nearest native dormouse population is located in west-central Staffordshire with others somewhat farther away in Shropshire and Cumbria.

Dormice were reintroduced to a site in the Middle Derwent Valley in 2003 by PTES as part of English Nature's Species Recovery Programme and have since been monitored by DMG. A similar reintroduction took place in 2002 in the Staffordshire sector of the Peak District, not far from the county border. In September 2004, a female with 2 very small young was found, the first direct proof of breeding at the release site, although breeding almost certainly also occurred in 2003.

A second reintroduction in the county took place in June 2005 on the Chatsworth Estate, and new-born young were found there in September 2005. This colony appears to be flourishing.

Both sites are monitored by DMG. Two supplementary monitoring techniques are also used: the traditional search for hazelnuts opened in a diagnostic way by dormice – these were numerous in 2003 – and provision of small feeding cages, specially designed by the first site owner. These are provided with biscuits and apple – which cannot be reached by grey squirrels - and use by dormice is shown by the presence of characteristic droppings and feeding signs.
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Species identification information