Movements and hibernaculum site in the fat dormouse (Glis glis).

Abstract

The fat dormouse (Glis glis) was introduced to Britain in 1902 (Corbet & Harris, 1991), but apart from distribution surveys (Thompson, 1953; Jones-Walters, pers. comm.) and reviews of damage done to forestry interests (e.g. Platt & Rowe, 1964), no detailed study has been made of its ecology. In some places, Glis has become a household pest, but it is not clear to what extent the animals which cause problems in houses also forage in surrounding woodland. Nothing is known about nocturnal movements, home range or normal foraging behaviour of the fat dormouse in Britain, nor is it known where the animals hibernate between September and May the following year.
Between July and October 1989 a pilot study of the fat dormouse was carried out by the authors at Wendover Woods, Buckinghamshire. This is a Forestry Commission site covering an area of approximately 3.5 square kilometres. The habitat is dominated by beech trees (Fagus sylvatica), with an understorey of elder (Sambucus nigra) forming localized thickets. There are also plantations of conifers, especially larch (Larix decidua) and spruce (Picea abies).
Two adult Glis (male and female) were caught in Monarch traps baited with sweet apple, and were fitted with radio-collars weighing 5 g each (Biotrack, Wareham, Dorset). They were trapped in an outbuilding located at the edge of the woods, where they nested behind a wall panel. They were studied to discover the extent to which they remained in the building, entered the adjacent house or foraged in the woods outside. They were tracked for 13 complete nights during early August, with position fixes recorded at approximately 30-minute intervals throughout each night. They were then monitored periodically to locate their daytime nests and later to find their hibernacula.
Once it became clear that they left the outbuilding to forage in the woods, a grid (covering an area of approximately 4.1 ha) was marked out, with the points at 15-metre intervals to aid position fixing. This allowed fixes to be recorded to the nearest 5 metres, using x, y map co-ordinates. Total distances travelled were calculated as the sum of straight line distances between successive position fixes. Whenever possible, the animals were observed by using a headlamp fitted with a red filter.