Foraging behaviour of White-backed Woodpeckers Dendrocopos leucotos in a primeval forest (Białowieża National Park, NE Poland): dependence on habitat resources and season

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 (29–41%) 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.