Features of Migration of Young Greater Spotted Eagles from the European Part of Russia

Fifteen juvenile greater spotted eagles (Clanga clanga) in the central regions of European Russia and the Middle Volga region were tagged with GPS–GSM trackers, which made it possible to determine the length of migration routes (passing through arid regions and abroad) and the duration of autumn and spring migrations, to analyze the spatial distribution within these routes, to identify the locations and duration of migration stops, and to determine the mortality rate and also the dates of the beginning of departure. It has been established that the duration of migration, which varies greatly among individuals, depends on the distance of wintering areas from the birthplaces of the birds and on the presence and duration of migratory stops. The location of migration routes varies significantly not only among birds from the same population, but also among individuals born in the same nesting area, and even among chicks from the same brood. The most significant factors influencing the start dates of autumn migration are the transition of the average daily temperature through 10°C and a sharp decrease in night temperatures. First-year birds begin their migration later than birds older than one year old. The patterns of use of the territories where long-term migratory stops of the two individuals were recorded differed significantly. Mortality rates for the greater spotted eagles are highest during the first autumn migration.