Strategia di occupazione dello spazio cella marmotta alpina (Marmota marmota) in relazione a fattori ecologici. Space occupation by alpine marmots in the natural reserve of La Grande Sassière (Savoie, France) [Occupation de l'espace par les marmottes alpines dans la réserve naturelle de la Grande Sassière].

Résumé

The strategy of space occupation by Alpine Marmot (Marmota marmota) was studied at the population level in the Nature Reserve of La Grande Sassiere (Savoie, France). Along two main directions (a north-south axis and an east-west axis) 88 sampling areas of 0.25 hectare each (quadrats) were selected. Six ecological factors were recorded: sun-exposure, slope, plant cover, altitude, anthropic pressure and sun-shine duration. The occurence of marmots on quadrats was also recorded. Data were processed by use of a Logistic Linear Model. Results indicated that marmots were widely distributed in the reserve (67% of the quadrats). The ecological factors influencing the probability of settlement of marmots are sun-exposure, slope, plant cover and the interaction sun-exposure slope. The most propitious situation is represented by a southward exposure, a slope from 15 to 45 % and a rate of plant cover from 25 to 75%.