BIOLOGY, DAMAGE AND CONTROL OF THE EDIBLE DORMOUSE (Glis glis L.) IN CENTRAL ITALY

The remarkable increase in the number of colonies of edible dormouse (Glis glis L.) registered in the litoranean industrial cultivations of Pinus pinea L. in northern Tuscany over the last ten years and the grave damage to the production of pine-seeds consequent on it has created the necessity of studying systems which may reduce the dormouse menace. Going on what has previously been discovered about the habits of the species in this particular habitat, three different methods of control were experimented: direct capture in their nests, which were in this case cavities in the tree trunks which woodpeckers' activities had made accessible to the dormice; capture by means of specially built artificial nests; distribution of bait composed of pine seeds poisoned with chlorophacinone. All three systems the first two of which can be conveniently used together are worth further investigation and experiment, considering their results, to examine their individual advantages. INTRODUCTION The past ten years have seen a generalized and constant increase in the edible dormouse (Glis glis L.) populations in the ambit of certain coastal forests of Tuscany (central Italy). This arboricolous paleartic rodent is widely diffused in Italy and a common inhabitant of mixed latifoliae and conifer forests, but its presence has assumed the dimension of a plague in the ancient litoranean forest of Migliarino, near the town of Pisa. This forest covers a flat, almost rectangular area of about 3000 ha bounded by Ligurian Sea to the west, and a wide expanse of cultivated land on the other sides. At the present day the forest consists on the whole of umbrella pines (Pinus pinea L.) in close association with ilex (Quercus ilex L.) and oak-trees (Quercus peduncolata Ehrh.). It is largely the result of intense reafforestation carried out 150 years ago, in view of a later industrial exploitation of the pine seeds. In fact nearly 5000 tons of pine cones have been gathered there each year since the beginning of the Century, from which the pine kernels are mechanically extracted and the seeds removed, on the spot. These seeds are a product of high commercial value and are totally absorbed by the confectionary industry at home and abroad. The fact that the dormouse is overrunning this forest in particular has brought a grave situation in the production of umbrella pines so much so that opportune and drastic measures have had to be implemented to control their increasing number. In the period between 1969 and 1975 alone, the annual reduction in production attributed to the dormouse was 1550 tons of pine cones, for the total sum of 110 million liras (calculated in 1976). Since the Italian literature on the subject is scarce and vague (Zocchi, 1957; De Rosa, 1959; Bazzea, 1966), we considered it necessary to undertake a series of experiments using traditional old methods, already empirically employed locally, on a scientific basis, and at the same time perfecting some new ones. This experimental program was, of course, preceded and accompanied by observations on the biology and ethology of the species in this particular environment. BIOLOGICAL NOTES 1. Hibernation and Activity The edible dormouse is an animal which, at the onset of winter weather, goes into a long period of hibernation. This means that in the litoranean forests of Tuscany it is active on an average for about 186 days a year, from late Spring until well into the Autumn (see Table 1). 2. Natural Nests The edible dormouse is a species of pre-eminently crepuscular and nocturnal habits and passes the daylight hours in inactivity, inside various types of refuge. For the particular forest which we are interested in, its shelter is the cavity inside the trunk of the more ancient plants. The dormouse usually reaches them through holes pecked out by birds of the genera Picus and Dendrocopus. During the summer these cavities are occupied by single females (who give birth there and raise their young) and by whole groups of varying size and mixed sex. These refuges, in daytime, give shelter to practically the whole dormouse population. They do not seem to build a true nest or to remodel old ones of blackbirds (magpies or crows in this environment) as they do in younger forests where such cavities are infrequent. It can however be generally said that this animal has a marked tendency to occupy, and sometimes in large number, any sort of natural cavity (or even those artificially predisposed) as a permanent refuge.