Importance of nest boxes for breeding birds in forest areas - the Wielkopolski National Park case study

The study embraced 159 nest boxes placed in three different study plots in the Wielkopolski National Park in western Poland. In the first season, 64% of nest boxes were occupied by four species: great tit Pants major, blue tit Cyanistes caeriileus, Eurasian nuthatch Sitta europaea and European pied flycatcher Ficedula hypoleuca. The dominant species were great and blue tits. Over 80% of broods of great tits and blue tits were reared successfully. Birds preferred nest boxes located in plots with domination of oaks and Scots pine and with rich underbrush. Woodpeckers damaged entrances of 70% of the nest boxes, but did not cause any brood losses. In 13% of the boxes nests of hornets, bumblebees and wasps were found. Bumblebees chose boxes with a bird nest material, whereas wasps and hornets avoided sites occupied by the birds. In general, the insects had a small impact on breeding success of birds and caused failure of only 3% of all broods. Obtained results show that nest boxes in forests may increase density of the most common cavity nesters and secure their high breeding success.