Nest tree characteristics of the Lesser Spotted Woodpecker (Dendrocopos minor) in boreal forest landscapes

Tree cavities, and especially cavities made by woodpeckers, are important microhabitats in forest ecosystems. However, the properties of woodpecker nest trees and cavities are poorly known even in boreal areas where most tree cavities are made by woodpeckers. We studied the nest tree characteristics of the Lesser Spotted Woodpecker (Dendrocopos minor) in a 170-km2 forest-dominated area in southern Finland during 1987–2018. The data included 97 nest trees with 106 nest cavities in five deciduous tree species. During the study period, more than one nest cavity (2–3) was excavated in 7% of all cavity trees. Nests were found in three forest types, but the proportions of nest tree species differed between them. Birch (Betula spp.) was the most common nest tree species with 40% of nests. Nest trees were either dead (79%) or decaying (21%), and the majority (69%) had a broken top.