Wybiórczość siedlisk leśnych przez głuszce (Tetrao urogallus) w polskiej części Karpat Zachodnich

The objective of this paper is to analyse the forest habitat selection by Capercaillie in Polish part of the Western Carpathians. The study was carried out in the Ujsoły Forest District located in the Beskid Żywiecki Mountains in years 2002−2004. Habitats were investigated with regard to the forest types, age classes of the main tree species, canopy closure and altitude. We established 28 linear transects of the total length of 221 km. Data regarding Capercaillie occurrence (n=141) i.e., bird observations, tracks, feathers and droppings were collected twice during spring, summer, autumn and winter. Average index of Capercaillie density based only on birds seen amounted to 0.055/km of the transect and was the highest during spring (0,090/km). Availability and usage by Capercaillie, as well as preference index were calculated for distinguished habitat groups. As shown by Bailey's test, mountain mixed coniferous forest and mountain coniferous forest sites were preferred by Caperacillie, while mountain deciduous forest was avoided. The birds preferred spruce and beech stands of age ranging from 80 to 120 years. Moreover, stands with open and broken canopy and habitats located 800−1200 m a.s.l. turned to be highly preferred by Capercaillie. The obtained results were analyzed in relation to potential food resources, predator pressure and human disturbance. The following forest management measures in mountain refuges of Capercaillie were suggested: (1) maintaining open or broken canopy closure of stands, (2) policyclic timber harvesting system with a long period of regeneration, (3) patchy distribution of understory vegetation with cover below 50% of area, (4) maintaining in the ground flora at least 30% cover of bilberry, and (5) leaving seed trees and old−growth forest patches in clear−cuts as well as promotion of natural regeneration. This activities together with control of predation and reduction of human pressure allows to protect Capercaillie population in the Beskid Żywiecki Mountains.