Nesting habitat, clutch size and nest failure of Capercaillie Tetrao urogallus in Scotland

摘要

Within Britain, the Capercaillie is amongst the redlisted Birds of Conservation Concern (Gibbons et al. 1996) because of its large reduction in range between the two breeding atlases (Sharrock 1976, G, ibbons et al. 1993). Hunting records indicate that the main period of the recent decline in Scotland took place since the mid-1970s (Moss 1994). A number of factors have been implicated in the loss of range and decline in population size: changes in silviculture, increased predation, overshooting, overgrazing by Red Deer Cervus elaphus and collisions with fences (Moss 1994, Catt et al. 1994). In recent years, breeding success has been low, indicating either poor clutch or brood survival (Moss et al. 2000). We examined temporal changes in clutch size and nest failure, to test if the decline was caused by poor nesting success. We also present descriptions of nest sites in different woodland types.