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Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	Seasonal occurrence and population trend of the Turtle Dove Streptopelia turtur at the German Bight
Auteurs :	Guenther Busche, Auteur ; Volker Dierschke, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (128(3) 2007)
Article en page(s) :	149-157
Résumé :	At the German Bight (SE North Sea), Turtle Doves occur much more often during spring migration (including summer migrants in July) than during autumn migration, the ratio of observed individuals is 2149:96 (i.e. 96:4, years 1972-2002) for Helgoland and 194:61 (i.e. 76:24, years 1963-2000) for the west coast of Schleswig-Holstein. The median dates of spring migration are 30(th) May (Helgoland) and 26(th) May (west coast), those of autumn migration are 13(th) September and 28(th) August, respectively. In average, 75 birds per year were observed on Helgoland, but only 8 birds per year at the west coast. In both areas, annual totals show a positive (but only at the coast significant) trend until the mid-1980s followed by a significant decline after 1986. Accordingly Turtle Doves observed at the breeding sites further inland in Schleswig-Holstein (Geest) did also significantly increase up to the mid-1980s and then significantly declined, leading to quite low numbers since the mid 1990s. With more than 30 years covered for each of the three sites, strong fluctuations in annual totals are obvious. However, there is no correlation between the annual totals of migrating Turtle Doves on Helgoland and at the west coast, but a significant correlation between breeding birds on the Geest and both Helgoland and west coast. The data failed to show any relationship to climate indices (NAO winter index, summer index).The much stronger occurrence during spring migration maybe due to birds with prolonged migration, whereas the weak autumn migration might be explained by the lack of potentially passing birds from northern Europe, where the species only very rarely breeds. The decreasing numbers of migrants since the mid-1980s are in line with declining breeding populations all over the northern half of Europe.

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