La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	[Only few birds return: Low stopover site fidelity of migrating landbirds on the North Sea island Helgoland.]
Auteurs :	Volker Dierschke, Auteur
Type de document :	Article
Dans :	Vogelwarte (41(3) September, 2002)
Article en page(s) :	190-195
Langues:	Allemand
Résumé :	Out of 84,827 landbirds (at most passerines) ringed on the small offshore island Helgoland (SE North Sea) during stopovers on spring and autumn migration from 1989 to 2000, only seven were recaptured in a later migration season (1 Sparrowhawk Accipiter nisus, 1 Robin Erithacus rubecula, 2 Redstarts Phoenicurus phoenicurus, 1 Song Thrush Turdus philomelos, 1 Garden Warbler Sylvia borin, 1 Common Whitethroat Sylvia communis). The resulting recapture rates for those species fell between 0.0001% and 0.0883% and were 0% in 19 other species. The probable reason for this low recurrence is that landbirds by chance interrupt their migration across the North Sea at Helgoland, because of either their diurnal rhythm or unfavourable weather conditions. Furthermore, recapture probability is low due to very short stopover lengths. As on the only small island (1.5 km2) resources are restricted and bird densities are often high, it seems to be more profitable to stopover in larger areas where more variation in habitat and food is available in combination with lower bird densities.

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