Factors influencing the white-backed woodpeckers' (Dendrocopos leucotos) choice of feeding trees in the Umeå region

Abstract: Saving the white-backed woodpecker (Dendrocopos leucotos) from extinction in Sweden has been an ongoing struggle for decades. Despite this, there have been remarkably few studies on the species ecology in Sweden, especially in the north. The aim of this study was to investigate if the white-backed woodpeckers living in the Umeå region show a preference regarding what kind of trees they use for foraging, based on the factors tree species, tree condition (dead/alive), and tree size. Data were gathered at three sites in the vicinity of the lower Umeå River region and was made up of holes left by the woodpeckers from excavating trees for food. By comparing the trees carrying these traces with a representative sample of remaining trees at the sites, a test for preference could be performed. The results from this study indicate that the local white-backed woodpeckers strongly favour trees of the Salix genus when deep-boring, and that they also have a preference for dead trees independent of species. No significant effect of tree size on foraging choice could be found, although this would ideally require further studies. These findings provide knowledge on the local behaviour of the white-backed woodpecker that could potentially be of importance for implementing precise conservation efforts for this area-demanding species.