Owl Pellets and Bite Marks on Nuts: Take a Walk in the Forest and Help Researchers Track Dormice

It is small and it’s cute.

And according to biologist Zenia Henriksdottir Hansen, the hazel mouse could also hold a key to understanding climate changes and engage the public in nature conservation, giving an insight into the effects of climate change on biodiversity and ecosystems.

"The hazel dormouse acts as an indicator species in Danish forests, meaning its health reflects the overall health of these forests. That’s why we’re interested in finding out where it lives," says Zenia Henriksdottir Hansen, encouraging the public to lend a hand.

- We’re looking for dormouse ambassadors of all ages who would like to go for a forest walk and search for signs of the hazel dormouse. This is an ideal family activity at a time when outdoor activities may be in short supply. The hazel dormouse is quite shy and nocturnal, so spotting one is rare, but there are several tell-tale signs of its presence. We’d like people to report these findings, explains Zenia Henriksdottir Hansen, a PhD student leading the interdisciplinary project, a collaboration among the Naturama Museum of Natural History, the Department of Biology at SDU Odense, and the Department of Design, Media, and Educational Science at SDU Kolding.

Biologists know that the hazel dormouse lives in South Funen and Central and South Zealand and that one was spotted in Draved Forest near Løgumkloster over the summer.

- This was the first confirmed sighting in Jutland in 13 years, so it was breaking news!, says Zenia Henriksdottir Hansen.

In the past, hazel dormice were found in Southeast Jutland (around Vejle, Kolding, Aabenraa, and Sønderborg) and on Langeland (Hestehave/Tranekær). However, aside from the recent sighting in Draved Forest, there have been no recent confirmed sightings in Jutland or Langeland.

In South Funen, there is a known population near Svendborg and Faaborg, with potential sightings further north near Snarup Mose, just outside Kværndrup.

In Zealand, dormice have been seen in three areas: around Sorø-Slagelse, the Bidstrup Forests near Lejre, and around Borup and near Rønnede outside Faxe. The Danish Society for Nature Conservation is also investigating possible populations in other parts of the country.

There are three different signs to look for during a forest walk:

1. Nuts with Bite Marks: Search for fallen hazelnuts and acorns. If you find a nut with bite marks, holes, or other openings, take it home and examine whether it’s the work of a dormouse. Place the nuts in a bag along with the coordinates of where you found them and drop them off at one of the designated nut stations.
2. Owl Pellets: Hazel dormice are prey for owls and other birds of prey. If you come across owl pellets, put them in a bag with the coordinates and deposit them at a nut station.
3. Nests: The dormouse builds a very distinctive nest from grass and leaves, which it uses during the summer. If you are lucky enough to spot a nest—easier to see once the leaves have fallen—it’s important not to disturb it. Instead, take a photo, note the coordinates, and send the information to the researchers.

If you own woodland or a wildlife hedge and suspect dormice may live there, you can set up a nest box. Dormice will happily use a nest box in the summer and fall, and you can check in winter to see if you’ve had visitors.