Foraging activity of woodpeckers on various forms of artificially created deadwood

Abstract

Many woodpecker species rely on different forms of deadwood for nesting and foraging. However, the knowledge of the effect of enrichment of their habitat with different types on deadwood of this species group is lacking. Complex conservation-oriented management, including deadwood enrichment, was applied in a 20 ha even-aged oak-dominated woodland in Hungary. The foraging activities of woodpecker species were documented on selected treated trees over one, two and three years since these measures were implemented. The 109 individual oak trees examined represented five deadwood types: Damaged-, girdled-, felled trees, and low- and tall stumps. We analysed the relationships between three variables (depth of foraging work, type of deadwood, and year) and foraging activity. Our results illustrated the prompt responses of woodpeckers to the treated trees. The woodpeckers used the five deadwood types in very different ways, and foraging activity was found to vary greatly in terms of depth of foraging and between years. More activity was carried out on both low- and tall stumps than on any other type one year after the treatment, whilst work on girdled trees and tall stumps predominated two and three years after the treatment. The utilisation of felled- and damaged trees by woodpeckers proceeded at a markedly slower pace than that of girdled trees and stumps, but the utilisation increased gradually. Most of the foraging activity was found to be on the outer bark, however, work on the inner bark and in the sapwood increased between the three years. The measures to conserve the woodpecker species should include the permanent creation and maintenance of various forms of deadwood to provide diverse and continuous foraging sites for woodpeckers.