Movement patterns of juvenile and immature eastern imperial eagles from Bulgaria

Abstract

Eastern Imperial Eagle (Aquila heliaca) populations in Central Europe and Balkans are non-migratory while most of those in the eastern part of the range are migratory. However, the juveniles from the non-migratory populations disperse over a large area. We studied the movement pattern of juvenile and immature Eastern Imperial Eagle from Southeast of Bulgaria using satellite telemetry. In total, 23 juvenile Eastern Imperial Eagles have been fitted with Argos/GPS transmitters in their nests in Bulgaria in 2008–2013 and seven eagles were tagged with GPS/GSM transmitters in 2021–2022. Dispersal distance varies significantly as some birds reached Israel, Syria, Saudi Arabia, and Africa while others wintered on the Balkan Peninsula and in Turkey. Majority of the birds spent their first winter outside Europe in Anatolia, Middle East, and Africa while three birds wintered in the Southeastern Balkans and one in the island of Crete. In the spring all eagles moved from the wintering areas to Bulgaria, close to their natal areas. Long distance nomadic movements northward during the spring and summer to Central Europe, Ukraine, Belarus and northernmost to Latvia and Russia have been recorded as well. The results indicate that international collaboration should be part of the conservation strategies for the Bulgarian Eastern Imperial Eagle population with Turkey as a key country for conservation interventions.