Thrushes (Turdidae, Aves) of Northern Eurasia: Their abundance, distribution and population characteristics

The article presents the results of our research on the population size, distribution, and characteristics of thrushes in Northern Eurasia within the 1990 USSR boundaries. The study utilized data from the Zoological Monitoring Laboratory’s database, collected intermittently between 1880 and 2022 (primarily since 1960) during bird surveys conducted from May 16 to July 15 along routes with a total length of approximately 165,000 km. Based on factor classification, six types of thrush populations were identified, whose boundaries correlate with climatic and geographical environmental features. Additionally, seven subtypes of communities were distinguished, varying in boundaries depending on forest coverage and thermal conditions. It was found that thrush population density and species richness increased in southern and western regions, while thrushes are absent in polar deserts and Arctic tundras. The research methodology, including cluster analysis data processing and the introduction of null species to account for extreme habitats, enhanced the informativeness of the classifications. The study results can be applied in conservation activities and ecosystem health assessments.