Foraging behaviour of the Great Spotted Woodpecker Dendrocopos major in relation to sex in primeval stands of the Bialowieza National Park

The Great Spotted Woodpecker Dendrocopos mujor in spite of its broad food niche may prefer some trees or places on them during foraging. Different preferences for foraging sites can also be found in males and females, which may minimize competition for food between them. The main goal of our study was to define sex-specific use of foraging sites of the Great Spotted Woodpecker, in the primeval oak-hornbeam-lime forest of the Bialowieia National Park, E Poland. This forest has never been logged and is distinguished by the structure of great vertical and horizontal diversity, high amount of dead wood and trees which reach large dimensions. Therefore, there are a large number of potential foraging sites, and some trees, due to their species or condition, may be particularly preferred in this respect. Our study revealed that the foraging sessions of woodpeckers were longer on the dead parts of trees than on alive ones which were especially noticeable in the case of females. The longest foraging sessions were found on dead parts of Norway Spruce Picea abies for both sexes. The males foraged the longest at high altitudes (> 20 m above the ground) on thin parts of trees (diameter 5-10 cm) whereas females on sites above 15 m and on thicker parts of tree (diameter 10-20 cm). Moreover, the duration of foraging session of females increased with increasing of trunk diameter at breast height, which was not revealed in males.