Home Range Size of the White-Backed Woodpecker Dendrocopos leucotos in Relation to Resource Distribution, Forest Area, and Intraspecific Competition

We investigated variation in home range size of the White-backed Woodpecker Dendrocopos leucotos, a species dependent on old-growth structures, in Central European forests varying in management intensity. Specifically, we used data from woodpeckers radio-tracked between 2016 and 2019 to test predictions of three hypotheses proposed to explain variation in home range size. Mean (± SD) 95% home range size calculated with fixed kernel density estimation was 22 ± 11 ha (N = 27) in the breeding season (» April and May) and 47 ± 27 ha (N = 28) in the post-breeding season (» June and July). Home ranges of neighboring individuals overlapped neither in the breeding season nor in the post-breeding season, suggesting territoriality in both seasons. The resource distribution and intraspecific competition hypotheses were supported during the breeding season, whereas neither hypothesis explained post-breeding home range size. Breeding home range size decreased with both increasing forest area in the landscape and increasing proportion of resource-rich habitat (snag volume and trees with dead branches), the latter being particularly relevant when forest area was low. Moreover, breeding home range size decreased with increasing population density when the proportion of resource-rich habitat was high. The mechanisms determining breeding home range size thus varied with habitat quality in the landscape. In regions with low forest area and presumably generally low habitat quality, home range size appeared to be influenced by the distribution of resources. By contrast, in regions with high resource abundance and high population density, home range size seemed to be regulated by intraspecific competition. To improve habitat quality, deadwood and old trees should ideally be clumped within stands with little or no forest management. These resource-rich forests should constitute a high proportion of areas at least the size of a breeding home range and are particularly important in little-forested regions.