Dormouse Update - Autumn 2007

The Cheshire dormouse population has made great progress since they were re-introduced to the county back in 1996. Regular monitoring has allowed us to see how numbers have increased and they have gradually expanded into new areas of woodland. Over the years the regular counts have also revealed other aspects of dormouse behaviour, such as their use of conifer trees (unknown back in 1996) and how adult dormice will remain in a very small area for several years. For the last couple of years we have been learning more about their behaviour by micro-chipping the dormice, so we can follow the movements and life histories of individual animals.

The weather this year has been especially challenging for dormice. Dormice don’t like getting wet; their fur is not water-proof, so they quickly get water-logged and cold. To avoid this, on wet nights they may stay in their nests, which means they cannot forage. In most year by July all the female dormice will have young, but this year the rain in July and early August will have delayed the start of the breeding season greatly.
With this in mind we approached the autumn counts, in September and October, with some trepidation. We need not have worried; while there were fewer young animals than last year it was obvious they had bred successfully, and all the juveniles found were very healthy. The previous year was exceptionally good for our dormice, with record numbers of young animals. Populations of small mammals such as dormice do vary from year to year, in response to varying environmental conditions, so we do not worry unduly about differences in number between years, as long as the overall trend id positive. The way the dormice have coped with this year’s adverse weather conditions shows how well adapted they are to their habitat.

By October they were preparing for winter. To survive hibernating through the winter dormice have to accumulate a thick layer fat. Some of the animals were very podgy indeed, weighing twice as much as they did during the summer. This shows they are finding plenty of food in their wood, and have a very good chance of surviving the winter.

Originally printed in The Grebe, Winter 2007