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Résumé :
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Redshanks were counted daily at three sites at the Gulf of Gdansk. The dynamics of migration differed between studied seasons. However, in the majority of years the pattern showed a clear wave structure. It is known that two different populations ("northern" and "southern"), which differ in biometrics and the migration time, migrate through the Gulf of Gdansk. The differences in migration timing of these groups are probably the main purpose of the observed wave structure. Weather conditions both in breeding areas and on route, have probably a remarkable influence on the observed multimodal pattern. The analysis of recoveries of ringed birds showed that in the first two decades of August juvenile Redshanks from "southern" population passed through the study area. They migrated both over inland and along the seacoast and the majority of them stayed in Europe for wintering. Late August and September migrants, which form main migration peak of juveniles in the Gulf of Gdansk, followed exclusively the coasts of Baltic and of the North Sea. These birds apparently belong to the "northern" population and they cross Europe finishing migration in Africa. They carry larger fat reserves than earlier migrants and the majority of them probably flies directly to the Wadden Sea or even to the Mediterranean. The heaviest birds are able to reach northern Africa in one step.
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