Dormouse Update
Cheshire Dormouse project has been running since 1996, focussing on a re-introduced population of dormice in the Wych Valley. Over the years our dormice have done well, gradually increasing in numbers and the area they occupy. In 2005 the project expanded dramatically. Several new partners joined us, principally Chester Zoo, the Forestry Authority and CCW. We have started work at a new site (Bontuchel near Ruthin), and embraced a new technology (micro chipping) to give a more scientific approach to population monitoring.
What are micro chips?
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
What are the advantages of micro chipping?
It 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!
In the early days of the dormouse project individual animals were identified by tattoos in their ears. This was discontinued as it was time-consuming to do, and stressful for the animals, and the tattoos were difficult to read. But it did yield some very interesting information about animals movements, how long they lived and social behaviour.
The chipping is being done by vets from Chester Zoo, we are very grateful to them for energetically lugging the heavy anaesthetic equipment up and down the Wych Valley to do the job.
What have we achieved so far?
It will be several years before we have enough data to analyse longevity and reproductive success, but we made a great start and have some interesting initial results.
We made 5 visits to the Wych valleyeach in 2005, and 4 to Bontuchel. In the Wych Valley 47 Animals have been chipped, and 26% have been recaptured at least once. At Bontuchel 89 dormice have been chipped, and 36% 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. This box was in a group of beech trees which had obviously had a heavy mast crop the previous year. It will take several years of data to prove if these facts are connected.
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.
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 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.
What Now?
In 2006 we intend to carry out detailed botanical surveys of the area immediately surrounding every box at both sites, this will let us analyse their habitat preferences in detail. We want to micro chip more animals, especially young animals, so we can show how far they travel. We particularly look forward to finding some of the dormice already chipped.
Originally printed in The Grebe, Spring 2006 |
