Effects of managed forests structure on woodpeckers (Picidae) in the Niraj valley (Romania): Woodpecker populations in managed forests

In this paper we present the abundance, distribution, nest-site characteristics and habitat analysis of woodpecker species in managed forests. The studied territory is part of a Special Protection Area for bird species. We found breeding evidence of six of the eight sedentary woodpecker species from Romania: Grey-headed-(Picus calms), Green- (Picus viridis), Great Spotted- (Dendrocopos major), Middle Spotted- (Dendrocopos medius), White-backed- (Dendrocopos leucotos) and Black Woodpecker (Dryocopus martius). The most abundant was the Middle Spotted Woodpecker. Middle Spotted-, Green- and Great Spotted Woodpeckers excavated nest-holes most commonly in oak (Quercus petraea), Black Woodpeckers in beech (Fagus sylvatica), Grey-headed Woodpeckers in aspen (Populus tremula). White-backed Woodpeckers used only oaks as nest-trees. Weak excavators selected large trees, dead trees or soft woods for nesting, but most of the species used primarily live trees for excavation. The average diameter of nesting tree, tree height, nest height and relative nest height did not increase with the body size of the woodpecker species. Nearest neighbor analysis indicated that the local distribution of woodpecker species in most forest fragments differs from randomness. Great Spotted Woodpeckers and Black Woodpeckers presented uniform distributions, while Middle Spotted Woodpeckers aggregated distribution. Tree diameter and diversity, relative abundance of oak and aspen but also altitude affected woodpecker abundance. Black Woodpecker and Middle Spotted Woodpecker presence depends on large trees and diversity of trees. The results will contribute to forest restoration operations.