Distribution and number of black grouse, Tetrao tetrix in southwestern Poland and the potential impact of predators upon nesting success of the species

During the winter period 2006/2007, research was carried out on the distribution and number of black grouse in coniferous lowland forest, Bory Dolnoslaskie and the Karkonosze Mountains in southwest Poland. During 27 workshops, more than 800 members of various hunting clubs and representatives of the local State Forest Service presented information about place, i.e., forest compartments, and date when black grouse was seen. Then, this information was put on forest maps. Birds that could be seen twice or more were arbitrarily excluded by time-space analysis. In Bory Dolnoslaskie, a declining black grouse population was present in 12 hunting districts covering 50.5 thousands ha of forest. The estimate of this species was 60 birds, i.e., 1.18 birds per 1,000 ha. In the Karkonosze Mountains, increasing black grouse population occurred in 8 hunting districts within a forest area of 30.1 thousands ha. The black grouse number was estimated to 169 birds, i.e., 5.61 birds per 1,000 ha. In the heather-land of Bory Dolnoslaskie, 200 artificial nests were distributed on transect lines between the habitat (A) where black grouse is still present and the one (B) where it disappeared, and 14 movable digital cameras with movement detector triggered by infrared sensor were temporarily located at randomly selected nests that were destroyed by predators. The picture analysis showed that raven (Corvus corax) destroyed 93.9% and red fox (Vulpes vulpes) 6.1% of the nests. All the nests were damaged within 7 days. The rate of nest damage was faster in habitat B. Population dynamics of lowland and mountain black grouse population is analysed and discussed.