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Conservation dormouse monitoring

The Hazel Dormouse (Muscardinus avellanarius) is one of our rarest and most endearing native mammals. It has become locally extinct in several counties in the UK within the last hundred years.

The demise of dormouse populations is mainly due to loss of habitat and changes in silvicultural practice, such as large scale reduction of traditional hazel coppicing

Roadford Lake

Recent surveys have revealed that Roadford Lake hosts a healthy population of Hazel Dormice and evidence suggests that dormice were present at Roadford pre 1989 before the valley was flooded and that remnant fragmented dormouse populations occur at various locations onsite.

In 2005 a study was initiated to identify whether dormice were still present at Roadford. Two study sites were chosen within the Local Nature Reserve. Southweek Wood Study Area 1 is dominated by hazel stands, with beech, sweet chestnut, sycamore and ash. The area also hosts abundant honeysuckle. This part of the woodland is probably of ancient origin, an indicator of which is the associated rich ground flora.

Southweek Wood Study Area 2 is dominated by planted hazel, beech, ash and sweet chestnut and has no noticeable honeysuckle. This part of the woodland was planted when the reservoir was completed. An unclassified road that links the A30 trunk road to the village of Germansweek separates the two areas and effectively creates an artificial barrier to dormouse immigration and emigration.

Fifty dormouse nesting-tubes were erected in the study areas to ascertain the presence or absence of dormice. The survey revealed that dormice were present, with nests consisting of strips of honeysuckle bark and fresh hazel leaves in a ‘ball-shaped' construction, being found in April 2005. Fifty Dormouse nest-boxes were then erected in May 2005 to replace the nest-tubes and most nest-tubes removed. Where a nest tube contained nesting material, a box was erected next to it and the tube left in-situ.

Eight boxes (16%) where used by dormice at some point during the entire eight-month study. Six boxes (12%) were occupied by dormice on the monthly survey dates. Dormice bred in one box and had successfully raised four, possibly five, young. All dormice occupying boxes were active and none were recorded as being torpid (asleep) during the survey. A total of 10 - 12 dormice were recorded.

The only other species recorded nesting in the dormouse nest-boxes was wood mouse (Apodemus sylvaticus). Five boxes (10%) were used and these were all in Study Area 2.

Surveying at Roadford Lake continues and each year the existing boxes are checked in May and September in accordance with the National Dormouse Monitoring Scheme. In early 2007 a further 50 nest boxes were placed in Slew Woods based on past records however despite regular checking these boxes were not used and March 2009 were moved to Coombepark Wood based on dormouse records in bat boxes!

All three areas plus an additional set of boxes in Goodacre Wood were checked in May and September 2012. The surveys once again gave positive results showing Roadford Lake as a stonghold for dormice.

Other Sites

In 2008 we commenced surveying at Wimbleball with 50 nest-tubes placed in Hurscombe Nature Reserve, West Hill Wood and the Eastern coppice.

To date dormice have not been recorded in Hurscombe or West Hill but the makings of a nest were found in the Eastern coppice. Therefore 30 nest boxes have been placed in this area and they are surveyed annually.

Surveys using nest-tubes at Trenchford Reservoir, Lopwell Dam, Burrator Reservoir and College Lake have been carried out but as yet presence has not been established at these sites. We do know from other records that dormice are present at Kennick Reservoir. 

Updated November 2012


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