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Detailed knowledge of the foraging behaviour of endangered species, especially in relation to available resources, may be useful in conservation management. I studied the year-round foraging behaviour of the White- backed Woodpecker in broadleaved, primeval Białowieża Forest (NE Poland), and investigated how foraging time was divided among various substrates and foraging techniques. Of the 13 tree species used for foraging, woodpeckers were most frequently recorded utilising the three most common tree species: hornbeam Carpinus betulus, lime Tilia cordata and spruce Picea abies (totalling 61-68% of observed time), and the proportional use of tree species did not change seasonally. Observations of birds foraging on snags increased and foraging on fallen trees decreased from spring to winter. Foraging was most frequently recorded on dead substrates (72-85%), usually those covered with bark. Mean time of foraging on an individual tree increased significantly from spring to winter. The foraging techniques most often used by woodpeckers were bark-pecking (29-11%) and superficial wood-pecking (12-27%). During winter, foraging techniques did not change significantly in relation to weather. These results suggest that forest stand composition is less important to this species than tree condition. Most broadleaved tree species and, under some conditions, spruce can be utilised for foraging by this woodpecker if they provide dead or dying substrates.
Woodpeckers are a very good indicators of forest naturalness. The fact that many species of these birds are in decline in central and western Europe resulted from changes in forest management (e.g. favouring coniferous forest, removal of dead trees). The aim of this research was to evaluate the importance of patches of deciduous species for the occurrence of some specialized woodpeckers in the conditions of Scots pine dominated stands. The study focused on species associated with deciduous forest, i.e. middle spotted woodpecker Leiopicus medius (L.), white−backed woodpecker Dendrocopos leucotos (Bechstein) and grey−headed woodpecker Picus canus (Gmelin). Statistical analyses were performed for the woodpeckers, which occurred in more than 10 territories. The studies were performed in 2015−2017 in the southern part of the Sandomierz Basin in three study areas (52,6−59 km²). Two plots were dominated by black alder Alnus glutinosa and oak Quercus sp., while the third one was characterized by the highest share of black alder, followed by silver birch Betula pendula and oak. Deciduous trees at the age over 80 years accounted for less than 2% of the total area of each plot. The most abundant bird species in patches of deciduous forest was the middle spotted woodpecker (25 territories), while the rarest was white−backed woodpecker (1 territory). Grey−headed woodpecker appeared in 12 territories. The density of woodpeckers in deciduous forest areas ranged from 0.45 territories/100 ha for grey−headed woodpecker to 1.54 territories/100 ha for the middle spotted woodpecker. In the alder patches we found all territories of grey−headed woodpecker, 24% territories of the middle spotted woodpecker and single territories of white−backed woodpecker. The patches dominated by oak accounted for about 76% of territories of middle spotted woodpecker. The average area of the patches with presence of middle spotted woodpecker and grey woodpecker was significantly higher than the patches where woodpeckers were absent. The middle spotted woodpecker occurred in the forest patches with the highest average age. Redundancy Analysis (RDA) demonstrated that the occurrence of middle spotted woodpecker was most strongly associated with the area of the patches over 10 ha, while the grey−headed woodpecker preferred mature forest stands of alder. These species abundance was negatively correlated with a patch area less than 10 ha.
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