Spatio-temporal distribution of migrating raptors: A comparison of ringing and satellite tracking

Abstract

We describe the migration performance of three long-distance migrating raptors, osprey Pandion haliaetus, honey buzzard Pernis apivorus and marsh harrier Circus aeruginosus, and one short-distance migrating raptor, common buzzard Buteo buteo based on Swedish ringing recoveries and satellite telemetry, respectively. Tracking by satellite can provide detailed information about the exact timing of migration, migration speed, migration directions, stopover sites, and detours, thereby overcoming many of the potential biases found in ring recoveries. Comparison of the results from these two methods revealed agreement in the geographical distribution of the studied Swedish raptor populations during autumn migration and the winter period. Satellite tracking, nevertheless, provided much more detailed information in Africa and revealed significantly faster migration progress than indicated by ring recoveries. The implications of our findings for interpretation of migratory connectivity and the understanding of migration are discussed. © 2009 J. Avian Biol.