Dr. Layla Al Musawi from the Kuwait Foundation for the Advancement of Science and Greater spotted eagle 6491 just before release at Al Jahra Reserve, Kuwait, 16 December 2021.
6491 was captured as a juvenile at Al Jahra on 16 December 2021 meaning it had been hatched during summer 2021. Since capture it has sent back 238,987 locations and travelled 78,142 km (Figure 1).
Although caught at Al Jahra Reserve, in recent years 6491 has spent most of the winter in moist areas surrounded by agricultural lands, mostly in Iran (south of Ahwaz and near Dezful; Figure 2). The apparent wandering of this bird seems to run counter to the winter-time fidelity shown by most eagles, however not when one considers the inexperience of this bird (it was about 6 months old when caught) and the fact that Al Jahra is a part of a larger wetland, the Mesopotamian Marshlands, which Greater spotted eagles would find attractive.
During its first summer after capture, 6491 moved in northern Kazakhstan and did not settle into a territory. In subsequent years it moved farther north and east and summered in southern Russia, north of the city of Omsk. The areas over which 6491 in southern Russia have become smaller over time, signalling, perhaps that it has occupied a territory and may attempt to breed (Figure 3).
Spring and autumn migration routes uses by 6491 passed south of the Caspian Sea (Figure 1). Spring migration commenced during 25 March – 12 April and ended 7 April – 7 May. The lateset arrival was in the spring after capture, and was expected because the eagle was immature and was not of breeding age. The average daily travel distance varied between 123 and 247 km. The longest distance covered in a single day during spring migration was 575 km. Overall, spring migration covered 2986 – 3585 km, the distance being accounted for by variance in routes, and different summer and winter range locations for this bird when young. Autumn migration started during 22 – 24 September and took 8 – 19 days to complete. 6491 arrived on the wintering grounds during 4 – 12 October. On average, 6491 travelled 187 – 363 km/day on autumn migration; maximum daily travel was 508 km. The distance covered during autumn migration was 2926 – 3521 km.
The movements by 6491 are interesting because they show changes related to the age of the eagle and perhaps its reproductive status. 6491 is still transmitting, and is expected to arrive on its wintering grounds in October.
