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Dormouse monitoring Credit: Ian Court


Latin name: Muscardinus avellanarius

Hazel dormice were formerly widespread in woodland across Britain but there has been a considerable decline in both range and numbers in the last 100 years as a result of changes in woodland management, primarily the loss of coppiced Hazel woodland, the loss and inappropriate management of hedgerows and increased isolation of suitable woodland habitat. This led to the extinction of this species in Yorkshire during the preceding hundred years. 

To try and revers these declines, a national plan to maintain, enhance and re-establish Dormouse populations within their historic range was developed.  Following several reintroduction programs in Yorkshire at a site in the North York Moors National Park in 1999 and near to West Tanfield in 2004, a collaborative project involving the People’s Trust for Endangered Species, Yorkshire Dales National Park Authority, Natural England and the Common Dormouse Captive Breeders Group was developed.  This resulted in 35 captive bred animals being released into Freeholders Wood, near Carperby in Wensleydale in 2008. 

Annual monitoring work is undertaken by staff and volunteers from the Yorkshire Dales National Park Authority as part of the National Dormouse Monitoring Program.  This involves licensed fieldworkers checking nest boxes once each month from May to October and recording the number of Dormice nests, adults and or young. This work has shown that since the original reintroduction, the population has increased and continues to spread through the woodland. 

Following on from the success at Freeholders’ Wood, the Wensleydale Dormouse Project was started in 2018 with the aim of creating a contiguous network of appropriately managed woodlands and hedgerows in the mid-Wensleydale area, to facilitate the expansion of the Dormouse population from the successful reintroduction site at Freeholders’ Wood.  The project is a partnership between the YDNPA and Peoples Trust for Endangered Species (PTES), with the help and support of local landowners and managers, the Bolton Estate, the Yorkshire Dales Millennium Trust and Natural England. The project has undertaken surveys and condition assessments of hedgerows and woodland, so that targeted management work can be undertaken to create a connected network of well managed habitat that will enable the Dormice to disperse into and thrive in mid-Wensleydale. 

As part of the project, a secondary reintroduction was undertaken in a nearby woodland in 2016.  Although it is still at an early stage, the initial signs are promising with Dormice found throughout the wood. 

People’s Trust for Endangered Species – Dormouse