Ecology of the capercaillie (Tetrao urogallus) and forest management in relation to its protection in the West Carpathians

Abstract

Ecology of capercaillie (Tetrao urogallus) was studied in the mountains of Central Slovakia (West Carpathians) in 1981–2003. In the studied area, the capercaillie population inhabited especially old natural forests (100–250 years old) in the spruce-beech-fir (850–1,270 m a.s.l.) and spruce (1,250–1,530 m a.s.l.) vegetation zones. The overstorey stand age ranged between 80 and 250 years with the mean of 128 years. The understorey stand age ranged from 10 to 60 years. The overstorey tree density ranged between 200 and 1,050 stems per ha (mean 725). The understorey tree density ranged from 5 to 650 trees per ha (mean 290). Both males and females preferred old forests throughout the year. The results demonstrate a marked decrease (> 50%) in the numbers of cocks and hens on twelve monitored leks (28%) and a slight decrease (< 50%) on ten display grounds (24%). During the study period, capercaillie cocks became extinct on seven (16%) leks and in their surroundings. More or less constant numbers were found on twelve leks only (28%) and a slight increase occurred on two leks only (4%). A statistically highly significant correlation was found between the area of old-growth forest and the number of cocks attending a lek. In addition to forest deterioration predation appeared to be of major importance in limiting the numbers of capercaillies. Key points for forest management in relation to capercaillie protection are suggested.