The resurgence of the dormouse
Big predators can drastically impact surrounding ecosystems. But other species in the middle of the food chain can be important indicators of environmental success. And, local to us here in Cambridgeshire, the reintroduction of one small animal is teaching us about the quality of our woodland, and has been a big benefit for participating members of the community. Julia Ravey spoke to Gwen Hitchcock from the Wildlife trust for Bedfordshire, Cambridgeshire & Northamptonshire and went to Brampton Wood in Huntingdon to find out more from volunteers Roger and Sarah Orbell…
Julia - Ah... So is this a box waiting to go out?
Roger - Yeah, these are just some new boxes. We've got our local friendly shed group, like 'men in sheds' type groups.
Julia - Oh yeah.
Roger - This is the same sort of equivalent in Brampton on the RAF camp. And they've just set up in the last 12 months, mainly for mental health and people that wanted to do some things as well, some projects over the winter months, and they've been making these for us this year.
Julia - What I was being shown was a small wooden box. One of the many which are scattered throughout Brampton wood in Huntington, Cambridge, these boxes are designed to house a tiny rodent. The door mouth
Gwen - Dormice are really fascinating, small rodents. They are arboreal, so they live in trees. They do come down to the ground, but not very often during the summer months. They also are very fussy about what they like to eat. So they need to feed on very high energy food sources, things like nuts and berries, which people always associate them with. Because they rely on these very specific food sources, which aren't available over winter, that means they hibernate. Because of this lifestyle, they tend not to produce many young, so have quite small litter size. You tend to only get one, maybe two at most litters a year. Dormice are what we call an indicator species. So where you have dormice present, you know that you've got a really good quality woodland or hedgerow. So where we've been losing them, we know that's because the quality of the habitat has declined significantly.
Julia - Gwen Hitchcock, from the Wildlife Trust. Dormice numbers declined drastically at the beginning of the 20th century.
Gwen - So in Cambridgeshire, they went from being a species that was present and fairly common to being extinct in the wild. So a decline in the woodland management meant that a lot of woodlands got overgrown. The habitat became less suitable for dormice. We also have overmanagement of our hedgerows and hedgerows being ripped out completely during the intensification of our agriculture. And that also meant that there were less suitable habitats and also less connectivity for dormice to move around
Julia - In order to reverse this decline, an intervention was needed.
Gwen - Back in the early 1990s, the species recovery program decided to reintroduce dormice as a way to sort of facilitate getting them back into areas that they couldn't always reach. Cambridgeshire is the site of the first ever dormouse reintroduction in the UK. They got a small number, it was a mix of wild caught and captively bred dormice and released them into the Woodland over a couple of years. So in 1993, and in 1994. Following on from the reintroductions, they're all monitored. And that involves going and checking dormouse boxes every month during the summer and recording how they're doing.
Julia - And that's why I came to Brampton Wood, the site of that first dormouse reintroduction in Cambridgeshire, and met some of the volunteers who do these surveys.
Roger - I'm Roger Orbell and I'm the administrator for the Brampton Wood dormice project.
Sarah - I'm Sarah Orbell. I'm Roger's other Half. I just help with whatever I'm told <laugh> On this project.
Julia - <laugh> The boxes Roger was describing just before are crucial to monitoring the reintroduction. And they are designed specifically for dormice.
Roger - So basically instead of having the hole on the back next to the tree. We have the hole at the bottom.
Julia - Oh yeah. So it's different to the bare box where the hole will be on the front. Yeah. This one's underneath.
Roger - Yes. Yeah. So the dormouse goes and sits on the platform and then goes up through the hole in the bottom. And we sometimes have a wire mesh at the top or now we've just decided we've just changed this to perspex so that we can inspect the box without disturbing anything.
Julia - The presence of a dormouse or dormouse nest in these boxes indicate the species are living in the area surrounding it. Where these boxes live have shifted over the years to better understand how the reintroduction is going.
Roger - See that's the general outline of the wood. And they were all up in that 'Section A' originally. This is where they were released up here. We're now monitoring the whole wood, but just a single row of boxes down each side of each one of the rides. We now know that they're established in that original release site, but we just wanted to find out how far they traveled and to make sure that they are happy and dispersing in the whole area.
Julia - With many hundreds of boxes in the Woodland, it is important to note...
Sarah - They are not to be disturbed. We are only allowed to disturb them once a month on an official survey day. And we have licenses.
Julia - And while the boxes act as a good indicator that dormice are living in that area of the wood, they don't tell the whole story.
Sarah - I describe it as we're only seeing the tip of the iceberg. Hopefully, they should be in these natural underground areas and hiding in the stalls and the roots of the trees. Occasionally, some of them, you're lucky and you find it in a dormouse box, but it's a bit like geocaching, you know. You open the box and sometimes there's nothing in it. I think the best experience ever was opening one and seeing a mother and young. Okay. You're not allowed to disturb them and as soon as you realize that there are young in a box, the lid goes back on and you retreat. But just seeing it and if you've got young, you know that they're happy.
Julia - The dormice Roger and Sarah have seen seem to be very happy, but has the reintroduction been a success? Gwen Hitchcock.
Gwen - I think definitely, yeah. For long term success, you're looking for the dormice to be distributed throughout the woodland. So we reintroduce them into one small area and then we hope they move throughout the whole woodland. And also we then want to look at them moving beyond the wood to try and colonize new areas. And then at our site we've got both of these, we've got the dormice having moved all the way through the woodland. And we've also got them moving to the hedgerow through surrounding farmland.
Julia - But although the reintroduction of dormice in Cambridgeshire has been deemed a success story, we still need to protect these animals from human driven changes to our environment.
Gwen - So the big threat with climate change for our dormice is that our winters are getting warmer and wetter. And as an animal that hibernates, they need to put on an awful lot of weight to survive through the winter. Wintertime is the time of high mortality anyway. So between 40 and 70% of dormice don't make it over winter. And if your winters are warmer, they're gonna be waking up more. And if they wake up and there's no food there, that decreases their chances of survival through the winter. So we really need to do everything we can to try and make the habitat as best as it can be, to give them the best fighting chance to get through.