Will dormice travel along ropes in the canopy?

As one of only 29 species of dormice in the world, and as the UK’s only native species of dormouse, the Hazel dormouse (Muscardinus avellanarius) is rather special. The small nocturnal mammal is most commonly known for its iconic state of sleepiness; being both asleep in the day, and hibernating over the winter, finding a dormouse awake is a difficult task. Sadly, finding a dormouse in any state is hard enough.

Dormouse by Jacqueline Hartley

Dormouse by Jacqueline Hartley

Populations of dormice tend to be small: they breed only once or twice a year and are found in small numbers over large areas. In a 1 hectare home-range of optimal dormouse habitat, there might be only 4-6 adults. Habitat loss and fragmentation are also contributing to the fragility of dormice populations, as they are known to be mostly arboreal, and therefore need a connected woodland canopy to travel in search of suitable food as the seasons change.

As it is generally believed that dormice avoid crossing open spaces, creation of roads in woodland is a problem. Much debate has gone on over the cost and effectiveness of the dormouse ‘bridges’ that the Highways Agency suggest for mitigation. These can be a pole or rope stretched between trees, or a bigger structure such as a tunnel or tube. In 2012 dormice were found to be using Britain’s first wildlife land bridge over the A21 in Kent, however, beyond this, published scientific evidence that dormice actually use these structures is scarce.

At Brynna woods nature reserve, there is an abundance of hazel which has allowed nut identification and nest box surveys to confirm that there are dormice. The Wildlife Trust decided to carry out a project to see if it could be proven that dormice would actually use rope to travel in the tree canopies. Two types of rope: a thick 18.5 metre long natural rope, and a thinner 5 metre long rope made from sheep wool, were woven into the treetops of two trees.

To attract the dormice to the rope two flat willow platforms with a clay base were hung from the ropes in the trees at Brynna woods, and were bait with a small blob of peanut butter every week. Tied onto the trees branches opposite these feeding stations were motion sensitive cameras which would take a picture any time something landed on the platforms, or climbed on the rope.

Dormice Ropes

Dormice Rope

Within the first week there was an array of lovely, but non-target, animals visiting the ropes and feeding stations including squirrels, blue tits, great tits, and a blackbird. One photo however, taken at 4:41am captured a mouse on a branch near the ropes and feeding station. Despite the poor resolution of the photo this looks like a dormouse, as it appears to have the characteristic furry tail and large eyes.

After the mouse sighting the design of the feeding baskets was altered because of the large number of squirrels that were visiting. Dormice compete with squirrels in the wild for nuts and other food sources, and the squirrels were taking the peanut butter. The new basket design was a small flowerpot containing apple, secured into a woven ball of willow, with size limiting gaps.

Winter is upon us now, the dormice will soon be in hibernation, and as of yet the elusive dormouse has not since been seen on the cameras. But come the spring, the next stage of the project will be to try hazelnut butter as bait, and nest tubes on the rope.

Although this is a small project, it could potentially give us an insight into the movements of dormice at height on artificially introduced networks, and if successful, could help inform studies that might look at the effectiveness of dormouse bridges.