Aspects of the ecology and behaviour of capercaillie Tetrao urogallus L. in two Scottish plantations
A field study of capercaillie (Tetrao urogallus) was undertaken largely in the plantations of Monaughty and Culbin in Morayshire between 1977 and 1980, with additional observations in these and other forests between 1976 and 1982. In the mixed and structurally diverse Scots pine-larch-spruce plantation of Monaughty higher population densities and a sex ratio favouring males were recorded compared to the more uniform pine plantation of Culbin. Comparisons were made of the habitat available with that in which capercaillie were recorded, especially in relation to the species composition and age of stands. Seasonal and sexual differences in habitat use were found. Drive counts with many observers and transects with a single observer were used to estimate abundance and it was concluded that both methods were worthwhile provided large enough areas could be effectively sampled. Transacts on tracks had advantages over transects off tracks and winter transects over summer ones. Scots pine and dwarf shrubs were important in the diet. A study was made of physical features and chemical composition of conifers fed on, which agreed with some predictions based on earlier work, but indicated that caporcaillie may have been selecting needles rich in crude fat. Nesting dispersion in relation to mating sites and nesting density is described. A detailed study of nesting habitat indicated that dwarf shrubs provide important cover. Important behaviour patterns and the behaviour at the lek are described and interpreted. Evolutionary costs and benefits of the patterns in mating behaviour observed at one lek which was intensively studied for several seasons are discussed. Approaches towards improved capercaillie management and conservation are suggested.