FACTORS INFLUENCING THE DYNAMICS OF OCCURRENCE OF THE HAZEL GROUSE INA FINE-GRAINED MANAGED LANDSCAPE

The objective of this study was to test whether the pattern and dynami cs of occurrence of Hazel Grouse (Bonasa bonasia) in a fine-grained la ndscape mosaic could be predicted from the results of a study in a mor e intensively managed course-grained landscape with much less suitable habitat and a different matrix. Twenty-one years of regular inventori es of Hazel Grouse during spring, summer, and autumn and a vegetation map of suitable Hazel Grouse habitat were used to analyze the extincti on an d(re)colonization of Hazel Grouse in different patches in relati on to the size and isolation of the patch and the vegetation surroundi ng it. As predicted, patch area was the most important variable determ ining Hazel Grouse occupancy, (re)colonization, and local extinction. Also as predicted, the proportion of open habitat surrounding the habi tat (i.e., and isolation effect) was also important. The isolation eff ect occurred at a smaller scale in the fine-grained habitat than the i ntensively managed landscape. This was apparently related to the type of matrix open land in the fine-grained landscape and unsuitable, but forested, habitat in the coarse-grained landscape. The Hazel Grouse ap pears to be usually sensitive to habitat fragmentation, but the mechan ism causing the isolation effect differed between landscapes, probably because of the amount of suitable habitat left and the type of matrix in the landscape.