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Subject and Keywords:
nest-site selection ; riverine forests ; stand structure ; forest management ; nest-site convergence ; dzięcioł duży ; dzięcioł pstry większy ; Dendrocopos major ; Dendrocopos medius ; dzięcioł średni
The main goals of this study were to determine whether woodpeckers differ in nest-site selection between near-natural old-growth forests protected for ca. 50 years and managed forests. Great Spotted Woodpeckers preferred oaks as nest sites, but Middle Spotted Woodpeckers selected dead trees as well as live ashes and oaks. It was found that the degree of silviculture did not affect the preference for tree species between long-term protected and managed areas in either Dendrocopos species. However, the share of ashes as nesting trees for Middle Spotted Woodpeckers was distinctly smaller in managed stands. In primeval Quercus-Fraxinus-Ulmus riverine forests ashes are thought to have played an important role as a nest-site for this species. In unmanaged forests both woodpeckers nested in trees of a larger diameter, at a nearly twofold higher rate than in managed stands. Nest-height was influenced by tree diameter. However, these relationships varied between the two woodpecker species, in relation both to the type of management and to the tree species, and were the most pronounced in Middle Spotted Woodpeckers nesting in ashes in near-natural stands. The type of management did not affect the placements of nest-holes in relation to tree condition, state of tree stump and condition of the wood in either species. However, in comparison to the near-natural forests, both species excavated holes more frequently than expected in tree-trunks in the managed stands. The results of the present work suggest a convergence of some nest-site characteristics in managed forests.