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Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	Migration patterns of Common Gulls Larus canus ringed in the non-breeding season in Copenhagen and the surrounding area
Auteurs :	K. T. Pedersen, Auteur ; E. B. Fritze, Auteur ; S. P. Kharitonov, Auteur
Type de document :	Article
Dans :	Ringing & Migration (20(2) November, 2000)
Article en page(s) :	97-106
Résumé :	In the greater Copenhagen area (54degree59'-56degree07'N, 11degree55'12degree40'E) 4899 Common Gulls were ringed from September to April in 1976 to 1993. Up to 31 December 1993, 11,824 ring-recoveries from 2,388 gulls (49% of the total number ringed) had been received. Copenhagen lies on the Common Gull migration route from northeastern to western Europe. The directions of migration are southwest in autumn and northeast in spring. The autumn migration in some years lasts up to mid-January, possibly longer. Older birds migrate farther from the wintering grounds and further north than younger ones. The data suggest that annual mortality rate for second-year and older birds has not increased during the last two or three decades. Common Gull mortality rate steadily decreases with age at least up to maturity. Common Gulls, ringed in any part of the Copenhagen area, have almost equal likelihood of being found in any part of the recovery range. Gulls from different breeding localities or from different wintering grounds fly across the Copenhagen area in different days. The dates of movements of these groups vary from year to year and, possibly, depend on the particular year conditions. There are almost no recoveries from some regions in northern Europe of the birds ringed in the Copenhagen area, but the number of recoveries in the Copenhagen area from those regions is very large. At the same time, there are quite a few recoveries from northeastern Europe and central Russia. Since the numbers of Common Gulls in central Russia are currently increasing, one of the possible explanations of those facts is that young Common Gulls that were in some areas of northern Europe never return to breed. They hatched to breed southeast of their natal area, some in areas southeast of the White Sea. We suggest that a redistribution process within the European Common Gull breeding population is taking place but this problem needs further investigation.

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