The estimate of distribution and population size of black grouse (Tetrao tetrix) in Poland in the 1990 and principles of active protection project

The aim of the study was to describe changes in the occurrence of the black grouse (Tetrao tetrix) in Poland and to analyze reasons for these changes. The study was carried out in the whole country in the years 1993-95. Collected material was compared with the data from hunters' reports for the years 1982-94. On the basis of the results of the study and review of the available literature on black grouse, principles of active protection project for this species in Poland were elaborated. In the years 1982-94 the area of black grouse occurrence decreased by 45 percent and in 1994 it covered 6 percent of the territory of Poland, mainly in the north-eastern regions. Changes in the area of occurrence were correlated with changes in the population size, which decreased by 73 percent in the same period. In the late 1990 the decrease was continued. The number of black grouses was estimated to be 5.4 thousands individuals in 1994, and decreased to about 2 thousands in 1999. The main reason of this decline was draining and next agricultural or forestry management of moors, wet meadows and wastelands in river valleys and forests. It resulted in the loss of habitats preferred by the black grouse as well as in the decrease in availability of shelters and food resources in occupied habitats. The cover and food resources were further deteriorated by ageing of forests created by the afforestation of disused agricultural lands in 1950 and 1960. Habitat changes were accompanied by the increase in the numbers of predators, particularly red foxes and martens, which probably resulted in the increased of nesting losses and mortality rate. The most important task of the black grouse protection project in Poland would be an increase in the proportion of preferred habitats in areas of black grouse occurrence (renaturalization of moors, afforestation of disused agricultural lands, mowing of overgrown leking grounds) and other activities intend to improve nesting success (predator control, mowing of heathlands, conservation of areas with blueberries, changes in agricultural utilization of meadows, and limiting tourism, berry collecting or military training during breeding season of the black grouse).