Settlement, habitat preference, reproduction, and genetic diversity in recovering the white-tailed eagle Haliaeetus albicilla population

The recovering population of white-tailed eagles Haliaeetus albicilla was studied in Lithuania, Central Europe. In the present study, we focused on (1) clarifying which theoretical distribution model better fits and describes the observed pattern of eagle settlement, (2) examining habitat preference at the level of nesting territory and its relationship with reproduction, (3) ascertaining the genetic diversity profile of the population using D-loop mtDNA. Between 1985 and 2011, the white-tailed eagle population recovered from 0 to 120 pairs and by the end of the period occupied a range of 34,000 km2. As indicated by a mean annual breeding success of 0.67, productivity 1.15, and brood size 1.73, the population reproduced well. The pattern of habitat settlement during the period of population expansion was not random as high-quality habitats were occupied first. Supporting the ideal free distribution model, reproduction was similar across nesting territories in three different habitat types, as well as between territories established in different years. The eagles preferred aquatic habitats, but these preferences were not adaptive in terms of breeding performance. Increased brood failures in later years possibly indicated the growing effect of density-dependent regulation. In total, six different haplotypes were identified in the sample of 45 individual birds. Haplotype diversity was 0.711. Phylogenetically, the Lithuanian population is most closely related to the populations of Sweden, Poland, and Germany, while similarity with Lapland, Kola, and Estonian populations was evident too. These findings indicate possible source populations directly or indirectly participating in the process of recovery of the formerly extinct Lithuanian population. Haplotypes distribution across the three habitat types in Lithuania was uneven.