What are the Long-Legged and Upland Buzzards: Taxonomic Status, Hybridization, and Distribution

Previously, hybrids between the Long-legged Buzzard (LLB) (Buteo rufinus) and the Upland Buzzard (UB) (B. hemilasius) were not recognized as such; therefore, existing maps depicting extensive zones of sympatry do not correctly reflect the distribution of these forms. In this study, the tarsi of 555 buzzard individuals from 441 localities were analysed; their occurrence points were classified according to a newly developed morphological scale and plotted on a map. On this basis, a distribution map of the LLB, UB and their hybrids in Central Asia was created. A complete series of transitional forms extending over approximately 1,000 km excludes the possibility of drawing a boundary between the LLB and the UB either on morphological grounds or geographically. The proportion of UB features in hybrids increases from south-west to north-east and from lowlands towards mountains. In connection with climate warming and landscape aridization, a general shift of the breeding ranges of both species towards the north-east is observed. The authors propose to change the systematic position of LLB and UB in such a way that it is clear to the researcher that buzzards cannot breed sympatrically and that at each particular locality only one form may breed.