Discovering Dormice

I sometimes think that surveying for dormice is not all that it’s cracked up to be. Habitats generally considered to be dormouse-friendly are  distinctly not human-friendly. I spend far too many hours of my life fighting through the tangled branches of hedgerows and shrubby woodland undergrowth with a bag of survey equipment, trying to avoid the various armouries of nettles, bramble, blackthorn and gorse. And it is not only plants that seem out to get a dormouse surveyor; hornets are another hazard. They occasionally take up residence in a dormouse nest box and don’t take too kindly to being disturbed. Once, whilst scaling a hedgebank to reach a dormouse nest tube, I put my foot straight through a wasps’ nest. The wasps gave chase, but, as I made my escape, I dropped my rucksack and, luckily, the wasps focussed their attack on that, instead of me. On top of these things, I hardly ever see the animals I seek; dormice are rare and naturally occur at low densities, so I can go months on end without finding one.

I wasn’t raising my hopes, then, as I stuffed an old rag into the entrance hole of a nest box, lifted the lid and peeked inside. But, something stirred up the leaves inside. My heart began to beat a little faster, as I very gently shut the lid and lifted the box from the tree into an oversized plastic bag, so that I could examine it more closely. I remove the lid and a wood mouse peersout, whiskers working. It is always nice to see this delicate little rodent, but it is not the creature I’m looking for, so, I let it go, to scamper over the leaf litter.

The next few nest boxes are empty and I resign myself to the fact that it will probably be yet another dormouse-less survey day. Then, I come across a box filled to the brim with leaves. It is a characteristic dormouse nest, a woven ball of honeysuckle bark and leaves. But, the leaves are brown and the nest is cold. Its dormouse occupant has long gone.

A few boxes later, I find a perfectly formed dormouse nest, clad with fresh green leaves and my spirits lift at the knowledge that dormice must be close by. Dormouse nests are usually made of honeysuckle bark, leaves, grass and moss, but there are records of bluebell stems and bracken being used too. I have even seen strips of waxed paper bag incorporated into a nest. This nest, which includes a large wad of black and white badger hair, is unusual too. There is a badger sett within the woodland, but I wonder how the dormouse collected the hair. It is often stated that dormice are reluctant to descend to the ground, but surely it must have done to collect the badger hair? It has recently been shown that dormice cross open ground (busy dual carriageways in fact), so perhaps further research may show that dormice are more terrestrial than currently believed. 

As I approach the next box, a furry ginger streak races up the tree trunk to hang, squirrel-like, in the branches above. It stares at me with big black eyes, gripping one twig with its front feet and one with its back feet, its body swinging between them both. The dormouse must have heard me coming. Still, I take down the box to complete the check and when I lift the lid, I discover a nest with three juvenile dormice in it. They are active and orange-furred, so probably about 4 weeks old. They will stay with their mother for about another four weeks, accompanying her on nocturnal foraging excursions, then returning to the nest with her to sleep during the day.

I return the nest box to the tree and as I remove a thorn from my finger, I realise that getting a glimpse into the secret lives of these creatures might just be worth the scratches after all.

Now you do it

Why not take part in the PTES Great Nut Hunt this autumn (more details on the PTES website). Dormouse-nibbled hazel nuts are easily recognised. Dormice make a very neat circular hole, which almost always includes a part of the nut scar. This hole has a smooth inner edge and oblique tooth marks on the outer surface of the nut. Bank voles and wood mice leave ridges on the inner edge of the hole and squirrels are messier – breaking nuts into large, uneven pieces. Beware though – looking for dormouse nuts can be addictive and a walk in the woods may never be the same again!

Conservation status

Hazel dormouse is a UK BAP Priority Species that is legally protected under UK and European legislation. This means that you need a licence (e.g. from Natural England) if you want to carry out surveys for dormice and their nests. The hazel dormouse has been in a long-term decline, although there are signs that this decline is beginning to slow, which may be due to conservation efforts. However, wet summers are not good news for dormice and it may be that this year’s bad weather has an adverse effect on the UK population.