Status and management of black grouse in the natural park of Mont Avic (Italian alps) | Statut et gestion du tetras lyre dans le parc naturel du Mont Avic (Alpes italiennes)

The study area includes the basin of the Chalamy torrent (Aosta Valley, Western Alps) covered mainly with forests of Pinus uncinata (mixed locally with Pinus sylvestris and Larix decidua) and heath (above all Rhododendron ferrugineum, Vaccinium myrtillus and Vaccinium vitis-idaea), separated by stony ground, moors and small areas of grazing land. Over the 1960 hectares actually occupied by the species, the displaying males in the spring seasons from 1986 to 2000 were counted. For the period from 1992 to 1999, data were collected with regard to reproductive success by controlling, in the late summer, at least 20 percent of the females estimated to be present in the entire study area. The winter shelter sites were methodically searched during the period 1995/97. The availability, throughout the area of study, of environments actively selected by the species enables quite a uniform dispersion of the black grouse throughout the entire area to be obtained in all seasons. This is reflected by the average size of the displaying groups, which, even during years characterised by a high density (at least 3.5 males per 100 ha), did not prove to be more than 3.1. The richest arena included from 3 to 10 males and 33 to 72 percent of the males were isolated. In winter, the slopes facing the North (conditions of thick snow suitable for the digging of igloos) and the slopes facing the South (conditions of little snow: the black grouse shelter among rhododendron bushes or at the foot of young pine trees) were both regularly occupied. The density of the males during the spring varied in the period considered from 3.1 per 100 ha in 1987 to a minimum of 2.2 per 100 ha in 1995 and to an absolute maximum of 4.1 per 100 ha in 1999. The sharp reduction recorded in the period 1993/95, and the equally sharp increase in the years 1996/99 are correlated to the pattern of reproductive success: in fact, the reproductive index (juveniles/adult females) proved to be between 0.12 and 0.45 in the period 1992/94. Since 1995, it has had an average value of 1.22, reaching a maximum of 1.60 in 1998. This fluctuation is probably due above all to climatic factors. During the period considered, no significant variation was recorded in the study area or its surroundings in relation to the density of potential predators or interference of man. As far as the environmental characteristics are concerned, even since the 70s there has been a regular, gradual closure of woody and shrubby areas that were once used for grazing, the influence of which may only be evaluated in the long term. In addition to the regular monitoring and recording of all observations made, the Park Management Organisation has taken a series of initiatives aimed at safeguarding the species in the protected area. These initiatives have been partially integrated in a project financed in part by the 1996 Life-Natura European programme concerning, among other things, the SIC ®Mont Avic Forests¯: Restoration of abandoned grazing land with a view to increasing the ecotonal zones; Inclusion of sparse woods gradually being closed among the areas to be used for grazing cattle as from mid July; Standards for effective control of sheepdogs; Channelling of flows of tourists into an adequately signposted path network; Identification of sites of top-priority interest with regard to conservation (in particular, areas occupied steady in the course of the years by displaying males or breeding females and areas in which igloos are frequently found).