Tag Archives: muscardinus avellenarius

Dormouse box cleaning March 2016

After the long, dull months of winter, it was a relief to get back out in the woods, checking dormouse boxes. We always start the dormousing year by cleaning out the boxes, ready for the dormice as they emerge from hibernation. This year we also had some new nest boxes to install, bringing my site up to 50 boxes.

It was cold and overcast when we met on Saturday morning, but the stroll from the car park to the site warmed me up a bit, and after that I was too absorbed by the task in hand to notice the chill. I had a good team of volunteers helping me, so we got the new boxes up efficiently. We’ll find out next month if my mapping is good enough to help me find the new boxes again.

A newly installed dormouse box (Chateau Dormouse, as the child who helped make it called it)
A newly installed dormouse box (Chateau Dormouse, as the child who helped make it called it)

Dormice aren’t usually up and about in March, but this winter has been unusually mild. I’d heard several reports of dormice being found at other sites in Surrey already, so we approached all the established boxes with care. This paid off when we found a shrew in an old nest. Some of the old nests had deteriorated over winter, and had got damp or were messy from other temporary box visitors. These we cleaned out. Other dormouse nests appear to have been improved since our previous visit in November. These we left. A couple of boxes were showing early signs of new birds nests being built, so we left these as well.

Even better, we found a torpid dormouse in one of last year’s nests! This was a real treat, as the earliest dormouse I found at my site last year was not til June. It was very tightly curled, which made it difficult to sex. But it was a very healthy post-hibernation weight: 18g. After the winter break it’s always nice to start off with an easy to handle torpid dormouse.

Torpid dormouse asleep in a nest box
Torpid dormouse asleep in a nest box


Torpid dormouse being weighed
Torpid dormouse being weighed

So, a good start to the dormousing year. Let’s hope it continues that way, and the dormice enjoy their new boxes.


How was 2014 for dormice in Surrey?

This article is adapted from one that I wrote for the spring/summer issue of the Surrey Dormouse Group (SDG) newsletter, and is reproduced here with their kind permission. It's based on data collected by dozens of volunteers across the county. If you would like to find out more about the work of SDG, visit their website

Last year SDG members checked a total of 7076 boxes from 18 sites. Data from each SDG box check gets reported to the National Dormouse Monitoring Programme, to feed into their national analyses – you can read about how 2014 was for dormice nationally in the Dormouse Monitor.  Here’s a summary of the data from Surrey.

How many dormice?

We saw a total of 487 dormice over 2014. That works out at a mean average of 3 dormice per 50 boxes checked, but there was quite a range of numbers seen at box checks: from 0 per 50 boxes to 27 per 50 boxes. At a third of box checks no dormice were found. The median number of dormice found per 50 boxes checked was 1, which is probably a representative average, given that a few large numbers are skewing the mean. Some sites that had quiet starts to the season saw large numbers later on. On average, we also found 2 empty dormouse nests per 50 boxes (ranging from 0 to 18).

Number of dormouse found per 50 boxes checked, Surrey, 2014
Number of dormouse found per 50 boxes checked, Surrey, 2014

When did we see them?

The earliest dormouse was a 20g torpid male, found on the 6th March, and the latest ones were 3 found at the beginning of December (that’s not to say others weren’t around earlier or later – just we weren’t checking so didn’t find them). As you can see from the graph above, average numbers were highest in August to October, and lowest in March and April.

How much did they weigh?

Females weighed slightly more on average than males (19g vs 18.7g), but this changed considerably over the course of the year, as you can see from the graph, with weights at their highest just before hibernation. The heaviest dormouse recorded was a 33g female found in October.

Average weight of dormouse found in Surrey, 2014
Average weight of dormouse found in Surrey, 2014

Other interesting features

Dormice with white tail tips were reported 36 times over the year, including a family of juveniles, all with white tail tips. There were 9 dormice with stubby tails.


The earliest pinkies were found on 20th July. (Pinky is a technical term describing baby dormice before they grow fur). On that same box check the earliest greys (babies that have their first coat of fur, which is much greyer than an adult) were also found. The latest pinkies were found on 25th September, and the latest greys were found on 20th October. Dormice born later in the year have more of a struggle to fatten up in time for hibernation, but those born too early in the year may struggle with their mother not being able to find enough food for herself.

The largest number of dormice found in one box was 8 (mother with young): boxes with 8 dormice were found at two sites.

Other box occupants

Apart from birds (which seem to take over a large number of boxes in spring at some sites) and invertebrates, the most common other occupant were wood mice (162 were seen, 21 of which were found in dormice nests) and yellow necked mice (29 were seen, only one of which was in a dormouse nest). There were also 12 unidentified apodemus mice (wood mice or yellow-necked mice). The rarest other box occupant was the pigmy shrew, with only 7 reported over the whole year (2 of which were in one box).

Dormice! Bouncy baby dormice!

Please excuse the excessive exclamation marks in the title of this post. I am just rather excited about the dormouse box check at my site this month. Having only found one dormouse at my site so far this year (and even that was months ago), this month we found a whole family of healthy, lively dormice.

I think word must have got round Surrey Dormouse Group that my site isn’t the best bet for seeing dormice, as my only ‘volunteer’ this month was the wonderful Dr C. I think he brings me good luck with dormice, as we found the previous dormouse on a check when he was my only helper. Anyway, hopefully now we’ve got a few more dormice at the site, we’ll have more regular success so volunteers can get some dormouse handling practice.

The occupied box had a lactating mother with three lively, eyes open young. It won’t be long before they will be able to leave the nest and live independently (hopefully in some of our nest boxes).

Bouncy dormice
Bouncy dormice

Dr C saw the mother’s nose peer out of the nest when he was checking the box. It’s the time of year when dormice are busy having babies, so we knew that there was a real possibility that there may be young in the nest. That was quickly confirmed – as soon as we had put the box in the rubble sack and taken off the lid, the bag was full of four dormice dashing round at incredible speed. Having so far only handled one, torpid, dormouse this year, trying to safely catch and bag each of them was an intimidating prospect at first. But, after taking a deep breath and picking a target, I got the first one, and it got easier from there.

Young dormice are harder to handle than adults – there’s less to get hold of,  and their paws seem stickier, allowing them to climb arms more easily (something you have to keep an eye on when you’re dealing with several at once – you don’t want any escaping up your arm while you try to catch a different one).

After catching, weighing and sexing each mouse we put them carefully back into the nest. Not all of them seemed very keen on going back in, but once in they stayed there.

There’s plenty of food around, so they should have time to gain enough weight to hibernate through the winter. And they all looked in good condition.

Apart from delight at seeing lovely dormice, this new find is also really encouraging as the nest was in a different part of the wood to where we’ve found the other dormice nests.  We also found another new (unoccupied) nest in another part of the site. At some sites you find most of the activity in a relatively small area, but, from this first year of monitoring, it looks like they’re present across most of the monitoring site. While four dormice (one family) isn’t a huge number compared to some other sites, it’s the highest we have had so far, and I am encouraged by it.

Dormouse ecology (or how I got back into wildlife)

I’ve always loved wildlife, and being out in nature. But during my first few years of adult life, as a student living in big towns, I didn’t really act on that love. I’d go for country walks, and spend my holidays back in the beauty of Devon. I was always pleased to see exciting wildlife, like birds of prey, reptiles or even just bunny rabbits. But that was as far as it went.

Then, in 2006, newly married and living in the outskirts of London, it all changed. I had signed up to become a member of my local wildlife trust. One day their ‘what’s on’ brochure landed on my doormat, and, lured by a cute picture, I signed up for a one-day dormouse ecology course (the first of many courses I’ve done, and the beginning of a love affair with dormice).

Why do a dormouse ecology course

torpid dormouse
Torpid dormouse

My reasons for doing the course were pretty feeble – I knew practically nothing about dormice, apart from how cute they looked. I thought it would be an interesting way of spending a day off. That’s about it.

I was right. It was an interesting way to spend a day off. I did get to see lots of cute pictures of dormice. I even got a go at handling a couple. And I had my first experience of checking dormouse boxes.

One of the things that really struck me from the course (apart from how adorable dormice are) was that normal people, like me, could help with wildlife conservation. That there was still so much scientists don’t know about British animals, and that amateurs could help to fill those gaps. That was a bit of a revelation for me.

Dormice are fascinating creatures (as well as being undeniably sweet). They’re arboreal and nocturnal, so you’re not likely to bump into them, and they are rare in the UK. Add to that the fact that they spend several months a year hibernating – you could easily live within a few metres of a dormice and never see one.

There are other, more practical reasons for doing a dormouse ecology course, besides curiosity and liking cute pictures. Dormice are protected by law, meaning you need a licence to disturb them in any way. Doing a dormouse ecology course is an essential step towards getting your license, so is useful for professional ecologists and keen volunteers who want to contribute to dormouse monitoring.

Surrey Dormouse Group Ecology Course: 22 August 2015

Surrey Dormouse Group are running a dormouse ecology course on 22 August in Guildford. It’s a full day with classroom work in the morning, followed by a box check in the afternoon. There will be a charge for the day and you’ll need to bring lunch. It does not include dormouse handling, this is a separate course, but hopefully should include seeing dormice during the box check. You will receive a certificate of attendance at the end of the afternoon. There are only 20 places on the course, going fast, so if you would like to find out more, or would like a registration form, please email info@surreydormousegroup.org.uk for full details.

The course will be led by David Williams, a dormouse expert with years of practical experience, and the man who first introduced me to the delights of these beautiful animals.

The dormouse course I did, almost ten years ago, was the start of me getting serious about wildlife – realising how much there is to learn, and that I could get involved with studying and protecting it. Who knows, this year’s course may be the start (or another step towards) something special for you.