Past and present nest-site requirements of the Lesser Spotted Eagle (Aquila pomarina C.L.Brehm) and their possible conflicts with timber harvesting.

摘要

Recently, the growing demand for raw timber has resulted in the intensification of forest use in the Baltic countries. The aim of this study was to examine whether the increased timber harvesting during the last decade has influenced the requirements of the Lesser Spotted Eagle (Aquila pomarina) for their nest sites in Lithuania forests. In 2004, a total of 7% of checked Lesser Spotted Eagle territories were disturbed by forestry operations. The general tendency was that the characteristics of stands used for nesting differed from the average forest stand characteristics in the landscape less than a decade ago. Eagles were found to nest in 19 different forest types, while previously just 13 of such forest types had been recorded. Less productive forests (2nd site class) and normally irrigated stands were not avoided nowadays. The average age of nest stands decreased by 16 years. Though oak [Quercus] remained one of the most preferred nest-trees (20% of all cases), spruce [Picea] became the most common one (48%). This leads to the assumption, that the eagles are less selective nowadays than in the past. The increased timber harvesting during the last decade might explain why eagles switched to nest in stands, more similar to the surrounding forest landscape than in the past, and why some nest-site preferences remained and others disappeared. It is likely that during the next 30 years forest operations will be one of the most important factors having an effect on the Lesser Spotted Eagle population in Lithuania..