Diet of the hazel grouse Tetrastes bonasia in the west of the Arkhangelsk oblast

Diet of the hazel grouse Tetrastes bonasia was studied by the analysis of 268 crops have been collected in the Ilexa river basin (west of the Arkhangelsk Oblast, Russia) in 1981-1986, 1988 during spring (IV-V, n = 87), summer (VI, VIII, n = 81), autumn (IX-XI, n = 96), and winter (XII, II, n = 4). The index of fresh weight (%) was used. Spring diet was composed mostly of birch Betula sp. - 37%, willow Salix sp. - 18%, and aspen Populus tremula - 18%. From winter to spring, using of the field-layer plants increased very gradually, up to about 40% in May. In summer, 75% of the diet was composed of 3 plants items: bilberry Vaccinium myrtillus - 31%, cowberry V. vitis-idaea - 25%, and aspen -19%. Aspen leaves were eaten only in early summer, bun do not recorded in the August crops. Maximum consumption of animal food (5-6%) was noted in summer. Birch (22%), cowberry (27%), and bilberry (22%) were the main autumn foods. Birch, aspen, alder Alnus incana and rowan Sorbus aucuparia were found in the small winter sample. From April to October, hazel grouse realized an oligophagous strategy: despite the long list of its foods (more than 60 items), only 5 items (birch, aspen, willow, bilberry, cowberry) formed the main part (64-92%) of the diet by weight.