Grzegorz Zawadzki, Jan Paradysz, Aneta Kiec-Paradysz, Dorota Zawadzka
Characteristics of nesting trees of the white-tailed eagle in central Poland
Dendrobiology 2025, vol. 94: 139-149
https://doi.org/10.12657/denbio.094.010
Abstract:
The white-tailed eagle Haliaeetus albicilla is a large bird of prey that has increased its numbers in Poland and range rapidly in recent decades. It builds large nests on big branches of trees and has high requirements in terms of nest trees. The availability of suitable nesting trees may be a limiting factor for this bird species. In Poland, at the beginning of the 21st century, the Scots pine Pinus sylvestris has been the most common choice for the white-tailed eagle, accounting for 70% of nest trees. The aim was to assess the nest preferences of the white-tailed eagle colonising new areas in the fragmented forest complexes of part of the central European lowlands. We analyzed the white-tailed eagle’s nest trees in a newly colonised area of central Poland in the Mazovia Province. In 2023–2024, we collected data on about 90% of known eagle nest trees in Mazovia. It is an area of low forest cover and relatively young forest stand age. Measurements of nest trees and the immediate surroundings were taken. Of the 78 known trees, white-tailed eagles built 45% on the black alders Alnus glutinosa, 40% on the Scots pines and 15% on poplars Populus sp. Poplars and alders were selected much more frequently than would be expected based on their availability in the study area. The average age of the nest trees differed markedly between tree species. Pines were the oldest with an average age of 116, followed by alders at 84, and poplars about 70 years. The height of eagle nest placement was strongly correlated with tree height and age, while it was not related to the thickness of the tree. The poplars chosen by the white-tailed eagle was the youngest but thickest trees, providing a good support for the nest. Scots pine allowed the highest nest placement among species, and poplar the lowest. The main reason for nesting on poplars and alders is the limited availability of old, large Scots pines in Mazovian Lowland. The marked change in preference for nest tree species indicates the strong ecological plasticity of the white-tailed eagle.
Keywords: Haliaeetus albicilla, nesting tree, Pinus sylvestris, Alnus glutinosa, Populus alba