The North West Dormouse Partnership

Cheshire Dormouse project started in 1996, focussing on a re-introduced population of dormice in the Wych Valley. Over the years the dormice have done well, gradually increasing in numbers and the area they occupy. In 2005 we widened the scope of the project. This involved working at a new site and with several new partners, notably Chester Zoo, CCW and the Forestry Commission Wales. This became the North West Dormouse Partnership.

We wanted to collect more scientific information about our dormice, as there is still much unknown about dormouse biology. Most British dormice live in the south of the country; there are only a handful of populations north of Cheshire, in Cumbria and Yorkshire. It is likely that northern dormice are more challenged by climatic conditions than their cousins in the warmer south. We need to know more about their behaviour and requirements in the north if we are to conserve them effectively.

As part of this we have started monitoring dormice at a second wood, near Ruthin in north Wales. This wood, owned by the Forestry Commission, has a native population of dormice. Although it is less than 35 miles from the Wych Valley the conditions are very different, the vegetation is different and the wood is at a higher altitude. We hope to learn much by comparing these two populations.

With help from our new partners we are able to use a new technology, micro-chipping, to give a more scientific approach to population monitoring. This will enable us to identify individual animals, and so follow their progress over time.

Micro-Chipping
Micro-chips are a simple way of individually identifying animals. Many of you will have your dogs and cats micro chipped: if the animal gets lost anyone who finds it can have it scanned and you are more likely to be re-united with your pet. The micro-chips we use for the dormice are similar, but smaller, only 8mm long. The chip is inserted under the skin by a vet, while the animal is anaesthetised. The whole procedure takes just a couple of minutes, and the dormice recover very quickly from the anaesthesia. Micro-chipping has been used on captive dormice for some time.

Micro chip, showing small size

Micro-chipping means we can identify an animal every time we find it. Over time we can build up a database of information on each individual. We can find out how far they travel, how long they live, how far young animals disperse, and how many litters different females produce. There is still much that is unknown about dormouse ecology, and we are constantly discovering new things about them. One of our first observations of the Cheshire population was that they obviously hadn’t read the books!

Progress in 2005
In 2005 we micro-chipped 47 dormice in the Wych Valley, and 82 at Bontuchel. The latter is a much bigger site, and we soon realised it supports a very large numbers of dormice.

Of the 47 dormice chipped at Wych, 26% have been recaptured at least once, at Bontuchel 36% have been recaptured. At both sites most recaptures were close to the original capture site, and some were in the same nest box. This is very encouraging as it shows the dormice are not unduly disturbed by the chipping process.

We are also beginning to uncover aspects of dormouse social behaviour. At the Wych Valley some dormice have been found in male/female pairs. These pairs can stay together for several months, although they move between nest boxes.

At Bontuchel we found the animals often shared nest boxes, especially early in the year. In June we were astonished to find 6 curled up all together in a single box (usually we only find one or two adults in each box). This box was in a group of beech trees which had obviously had a heavy mast crop the previous year.

GIS
The locations of all the boxes at Bontuchel have been accurately mapped and entered into a GIS (Geographical Information System). This is a powerful system which enables us to see where the dormouse are, and compare this with habitat features, or other factors. It will also let us calculate the movements of individual dormice. We hope to map all the boxes in the Wych Valley early in 2006. We will also add information about the vegetation around each box, so we can see if this affects where they choose to live.

Like many other small mammals, dormice do better in some years than others. We think this is linked to climate, and the effect this has on vegetation, especially dormouse food plants. In both 2004 there was an above average crop of hazel nuts, hawthorn berries, sloes, and blackberries, all important late summer food sources. The dormice responded by breeding especially well that year, with many litters and 7 or more babies in each litter (the normal litter size is 4 or 5).

By contrast 2005 was not a great year for dormice, the cold spring meant they started breeding late, and the poor fruiting of hazel and other food sources in late summer further limited breeding. At Bontuchel we found only two breeding female the whole summer, and the Wych was only slightly better.
This is not anything to worry about, the long-term data from the Wych Valley shows dormouse numbers go up and down, but they quickly recover from a bad year.