You may be surprised to know that the number of hazel dormice (Muscardinus avellanarius) has declined by half since 2000 across many areas of Britain. The damage to, or complete loss of, woodland and hedgerows and the decline of coppicing are all responsible for a reduction in their population.

In addition, hazel dormice are being badly affected by unusual and extreme weather linked to climate change; warming winters are disrupting hibernation patterns resulting in them waking up when there is little food available.

Unfortunately, this trend has been observed across the BBOWT region, with woodlands once containing good populations of dormice having been reduced to much smaller numbers.

As a life-long small mammal fan, I was very excited to be able to attend a hazel dormouse ecology and surveying course, as part of my BBOWT ecology traineeship. During the course we undertook dormouse nest box checks under the guidance of a dormouse licence holder.

It was to my absolute delight that during the checks we found dormouse nests in several boxes and even a sleepy dormouse in one! This gave me great hope that when undertaking dormouse checks as part of my BBOWT ecology traineeship we might find some evidence of hazel dormice – it would prove not to be as easy as that!

Dormice are barely ever seen due to the fact they spend most of the day asleep. However, this can be used to an ecologist’s advantage when surveying for dormice. They readily make use of dormouse nest boxes (similar to a blue tit bird box but with the entrance hole positioned at the rear of the box).

Surveying using this technique, where you might encounter dormice or their nests must be undertaken by a dormouse licence holder and therefore is not a suitable technique for a trainee ecologist with no licence, like me.

Fortunately, dormice are very inquisitive and like to investigate new objects in their environment; therefore, a simple, non-invasive and cost-effective way to survey for presence or absence of hazel dormice is to make use to footprint tunnels; and it is this technique that my fellow ecology trainee, Dave, and I have been using this summer.

Footprint tunnel surveys are undertaken within BBOWT as part of a rolling programme to investigate sites with historic hazel dormice records, but where nest box surveys are impractical or have not given positive results. Also, there is some evidence to show that tunnels are more likely to pick up evidence of occupation than nest boxes.

Footprint tunnels are plastic tubes containing a sliding wooden insert. Thin white card is attached to the wooden insert and a strip of ‘ink’ painted at each end (the ink is actually a mix of olive oil and charcoal powder which is non-toxic to wildlife, although very fond of contaminating a trainee ecologist’s fingers, paperwork and clothing).

The tube and insert are attached to roughly horizontal branches in a woodland with strips of Velcro. Finding a suitable branch in a woodland is trickier than it sounds, and we had many debates about what would make a good place for a dormouse to hang out!

When dormice enter the tunnels, the ink is transferred to pads on their feet and the dormice leave their tracks on the card. Hazel dormice have very distinctive triangular-shaped pads on both their front and hind feet so if so if they have been through a tunnel you’d know about it, or at least that’s the theory!

Once footprint tunnels have been installed, they are left for a couple of weeks before being checked. This is the most difficult part of the survey – trying to find where you left the tunnels.

Despite our best efforts of taking notes, GPS references and making a map there always seems to be one or two tunnels that end up in a completely different place to where you think you remember you left them!

The other peculiar point to note about tunnel checking is that complete strips of the card can disappear - it turns out that snails have a penchant for it! When not eaten by snails, the card is inspected for prints.

On our first check at Bacombe Hill we were excited to find quite a lot of triangular-shaped prints on several cards and hopes were high, however when reviewed by our vastly more experienced BBOWT Ecology Team colleagues, we were disappointed to learn that the prints belonged to the non-native, edible dormouse (Glis glis). These dormice were introduced into a park to Hertfordshire in the early 1900’s and have established colonies within The Chilterns.

Sadly, subsequent checks revealed yet more edible dormouse prints and none belonging to hazel dormice. The tubes were removed from the wood where we first placed them and taken to a second woodland in the far west of The Chilterns, Warren Bank. Hot off the press – the tubes have just been checked and revealed yet more edible dormice prints.

Ecology is a wide field and I am not yet sure where it will take me, but hopefully I will find evidence of hazel dormice in Berkshire, Buckinghamshire or Oxfordshire in the not too distant future! Until then, the hunt goes on…

Samantha Darley, Ecology Trainee