Franceschi, P.F. de, Sepulcri, A., Filacorda, S. & Piasentier, E. 1997: The dietary composition of black grouse Tetrao tetrix in the Italian Alps. - Wildl. Biol. 3: 272.
The contents of the crops and/or gizzards from 54 black grouse Tetrao tetrix shot in the Italian Alps during October-November 1993 were examined. The frequency of foods in the diet was calculated by considering both crops and gizzards (16 birds) and by considering crops and gizzards separately (11 birds with crops and 27 with gizzards); the percentage dry matter (DM) weight of foods was calculated for the contents of 27 crops. The most frequently found ingredients were shoots of Vaccinium myrtillus (VM 67%), buds and leaves of Rhododendron ferrugineum (RF 50%), shoots of Larix decidua (LD 43%), fruits of Sorbus spp. (S 44%), and stems, leaves, fruits, and seeds of herbaceous species (A 56%; Geum spp., Galium spp., Anemone spp.). The same foods were also the most abundant when considering dry matter percentage (VM 15%DM, RF 17%DM, LD 12%DM, A 19%DM). The frequency and DM weight proportions of VM shoots were correlated with those of RF buds and leaves and shoots of Calluna vulgaris, whereas those of Rhododendron hirsutum buds and leaves were correlated with those of shoots of Salix spp. and needles of Pinus mugo. Buds of Fagus sylvatica were negatively correlated with the presence of Vaccinium shoots and positively correlated with Sorbus fruits.
Key words: black grouse, correlations, crop content, dietary composition, gizzard content, Italian Alps, Tetrao tetrix
Paolo F. de Franceschi, Museo Civico di Storia Naturale di Verona, Via Lungadige, Porta Vittoria 9, 33127 Verona, Italy
Angela Sepulcri, Stefano Filacorda & Edi Piasentier, Dipartimento di Science della Produzione Animale, Universita degli Studi di Udine, Via S. Mauro 2, 33010 Pagnacco, Udine, Italy