Bernd-U. Meyburg & Christiane Meyburg
World Working Group on Birds of Prey
Wangenheimstr. 32, D-14193 Berlin, Germany

INTRODUCTION Many species of birds of prey (Falconiformes) spend over half of the year outside their breeding territory, on migration and in their winter quarters. Whereas their behaviour during the breeding season is often closely studied, our knowledge of the remaining part of the year is very slight. For the past few years satellite telemetry has provided a new aid towards an intimate study of long-distance migrations.

METHODS During the period July 1992 till October 1996 we have fitted 57 raptors of ten different species , including 15 Steppe Eagles Aquila nipalensis, 14 Lesser Spotted Eagles A. pomarina, 7 Imperial Eagles A. heliaca, 7 Greater Spotted Eagles A. clanga and 7 Ospreys Pandion haliaetus, with satellite transmitters (PTTs) ranging in weight from 30 to 95 grams. 19 of the PTTs used, mainly since 1995, were solar-powered, the others had conventional batteries. After the early phase of the study, when more easily accessible nestlings were equipped, we moved to trap and study adult and immature individuals, which have the advantage of a higher survival rate.

RESULTS For the first time ever in ornithology it has been possible to track the full year-round migration movements in several species, e.g. in the Lesser Spotted Eagle, Imperial Eagle, Wahlberg’s Eagle and Osprey. The most impressive migration tracked so far was that of an adult male Lesser Spotted Eagle between its breeding grounds in northern Germany and its wintering quarters in Zambia, over a total distance of over 19000 kilometres. Some unknown migration routes have been discovered, such as the intracontinental trans-equatorial migration of the Wahlberg’s Eagle in Africa, the loop migration of the Steppe Eagle around the Red Sea, the crossing of the Osprey over the widest part of the Mediterranean Sea, the to-and-fro east-west migration of the Imperial Eagle between China and Saudi Arabia and the long-distance migration of the Greater Spotted Eagle south beyond the Equator. Through the introduction of solar-powered PTTs it has become possible not only to document the migration routes much more precisely than with PTTs with conventional battery supply, but also to study aspects such as migration speed, daily migration pattern, roosting behaviour etc.