Dormouse Nestbox Scheme
Wenlock Edge, the largest area of continuous ancient woodland in Shropshire, is a county stronghold for dormice. The Trust's woodland management, in particular the reversion of coniferous areas to broadleaved trees and coppicing, accounts for the thriving dormouse population. To encourage their success, we have a nestbox scheme that's been in place and monitored every year since 1999.
We started with 50 nestboxes, in clusters of five or six. Eighteen were placed among conifers to find out whether dormice would use them: we never found evidence of occupation, so we removed them and focused on monitoring other areas. The number of boxes fluctuated over the years, some falling into disrepair and others being removed when woodland was thinned.
We now have 27 dormouse boxes and check them twice a year. It’s like opening presents at Christmas – even if you don’t find a dormouse, there's nearly always something good. Surprised wood mice are most common and they quickly burrow down into their scruffy, leafy and often smelly nests. Yellow-necked mice have similar nests, but often leap out, bounding energetically over the branches. Blue tits manage to squeeze into the hidden opening and make a cosy nest of feathers and moss, and bumblebees can fill a box with exquisite hexagonal chambers.
Dormice typically make a neatly woven nest using stripped honeysuckle bark coated with fresh leaves. If you're lucky, they might pop their adorable heads out to see what all the fuss is about. As you can imagine, we've had some unusual finds and experiences: five years ago, a roost of brown long-eared bats were found crammed into two of the boxes. It seems that some dormice don’t read the manuals. Area Ranger Alistair Heath saw one run across the floor of a beech plantation (not a hazel in sight), in the daytime and in mid-January!
We monitor the nestboxes and our records go on our database and to the Shropshire Ecological Data Network (SEDN), helping to establish national population trends. It's hard to determine trends because populations and nestbox use depends on so many other things, including weather conditions and abundance of natural nest sites. However, dormouse records have been increasing nationally and our results have mirrored that.
In 2016, we found the highest number of dormouse signs ever in our nestboxes: 41% showed signs of use when normally we'd hope for 20%, with one box housing three dormice. This tells us that we're getting our woodland management right.
We've learned several useful things from this project. It's essential to have someone licensed to disturb dormice (either a committed volunteer or a member of staff) and important to map nestbox locations accurately to aid monitoring (difficult in dense woodland). We try to have boxes and volunteers ready to fit replacements as required. Finally, we check nearby bird boxes because dormice can often be found in them.