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Dormouse Monitoring Project at Dean Farm Trust 2022

Written by Katie Watkins


Hazel dormice, Muscardinus avellanarius, are the subject of one of the longest-running

monitoring programmes of any British mammal. The programme is now over thirty years old and currently includes counts of dormice at several hundred woodland sites each year across England and Wales. In Britain, dormice are found almost entirely south of a line between Shropshire and Suffolk. Counts of dormice in nest boxes since the mid-1990s show a steady decline.


Since 2000, the population has fallen by a half and dormice are classed as ‘Vulnerable’ to extinction under the red list criteria.

Alongside our wildlife rescue volunteer work this year I am proud to announce that we have been able to get involved with the National Dormouse Monitoring Programme run by the People’s Trust for Endangered Species (PTES).


Back in June we were undertaking a check of the few bat boxes that we have up in the woodlands near our flight cage when we noted the potential for dormouse in the woodlands and hedgerow in the area. With Dean Farm Trust backing I contacted PTES and we were able to secure 50 dormouse boxes through the box scheme that they run to assist the setting up of new dormouse monitoring sites. The woodlands where the boxes have been deployed has now been registered with the National Dormouse Monitoring Programme so any data we collect will be fed back into the programme.


Once the boxes arrived, we spent two Saturdays in August with our amazing volunteers where they learnt how to correctly deploy a dormouse box and to look for dormouse signs in the woodlands. These nest boxes are a particularly attractive substitute for natural tree holes and, where boxes are provided, a high proportion of the dormouse population may use them. The wooden nest boxes are similar to bird boxes but have the entrance hole facing the tree as dormice are an arboreal species they will climb up and down the main stem of a tree foraging for food where they potential could encounter one of our boxes and decided to build a nest.


We left the boxes to settle in for two months as sometimes they can remain empty for several years. Often the first signs will be nests rather than the animals themselves.

On Saturday the 29th of October we undertook our first check; To complete these checks you require a licenced person. The licence I carry allows me to survey hazel dormice by hand, including handling them in natural nests, nest tubes and nest boxes. Once biometric data has been collected you are required to release the dormouse back into their nest.

Dormice are not the only animals that will use the boxes however, so surveyors have to be aware when opening the boxes that they could come across other protected species such as bats, other small mammals such as woodmice and shrews or even bumblebees and occasionally hornets!


Rather unexpectedly as I never thought we would find a dormouse on our first check, in box 49 out of 50 we came across a beautiful male dormouse, who weighing 32 grams. He was definitely ready for winter! Within the centre of the box the dormouse had woven a structured nest from strips of honeysuckle and had surround the woven material with leaves collected from near by trees. Typically, the leaves are collected fresh and will be green or a faded grey in colour however this nest caught us a little by surprise with how many brown leaves had been added on a ‘roof’ making the initial look of the nest quite messy!

For a late October check this little chap was very active due to the warmer weather we have been experiencing, so after collecting his biometrics he was posted safety back into his nest inside the box.


I am really looking forward to all our future checks and would like to thank PTES again for there in support with their box scheme and Dean Farm Trust for allowing us to place the boxes into their woodland.

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