Migration routes of Steppe Eagles between Asia and Africa: A study by means of satellite telemetry

Abstract

We trapped 16 Steppe Eagles (Aquila nipalensis) on migration and on their wintering grounds and fitted them with satellite transmitters, 15 of them in Saudi Arabia and one in South Africa. Seven of the 14 Steppe Eagles trapped in Arabia in autumn did not migrate to Africa but spent the winter in the Arabian Peninsula. One adult migrated to southern Africa. The other six wintered in northeastern Africa, in some cases north of Bab-el-Mandeb, the straits at the southeastern end of the Red Sea, which they had crossed to reach the African continent. On their spring migration all eagles wintering in Africa migrated via the Suez, Egypt-Eilat, Israel, area at the northern tip of the Red Sea. This loop migration around the Red Sea is probably caused by east winds that blow from October until April, making the return migration difficult via Bab-el-Mandeb. This finding should help to explain the difference in eagle numbers between spring and autumn at such migration bottlenecks as Eilat, Suez, and Bab-el-Mandeb. Unlike eagles coming from Sudan and Ethiopia, eagles wintering in southern Africa must make a considerable detour of over 1200 km to complete this loop. The increase in Steppe Eagles overwintering in Arabia has probably contributed to the decline in the number of birds passing through Eilat in spring during recent years.