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La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	[Strong decline in the winter numbers of the Hooded Crow (Corvus corone cornix) in western Schleswig-Holstein/NW-Germany.]
Auteurs :	Guenther Busche, Auteur
Type de document :	Article
Dans :	Vogelwarte (41(1) Oktober, 2001)
Article en page(s) :	18-30
Langues:	Allemand
Résumé :	The winter numbers of the Hooded Crow in western Schleswig-Holstein have declined dramatically since 1965. A combination of methods (counts at roosts and sub-roosts, line transects, counts in study plots, a study of historical data) led to the following overview of Hooded Crow numbers in western Schleswig-Holstein: In the region close to the North Sea coast the numbers have declined to 10-12% of its size in 1965. The Hooded Crow is no longer a characteristic bird of the North Sea coastal region of Schleswig-Holstein. The density in other landscape types is extremely low. The high proportion of Hooded Crows that occurred on the sandy upland parts of Schleswig-Holstein was counted at roosts and sub-roosts. Estimates of winter numbers in the period 1965-1999 are presented. The small breeding population (only mixed pairs of C. c. cornix with C. c. corone and hybrids) is declining. According to ringing data, most of the Hooded Crows wintering in Schleswig-Holstein are breeding birds from Sweden and Finland. The decline in the Schleswig-Holstein winter population is due to changes in the migratory behaviour of Fenno-scandian Hooded Crows which have shortened their migration route and partly remain in their breeding areas. This development towards a non-migratory status is due to improved food availability in urban areas and to the improved breeding success of birds that winter in the breeding area. Climatic changes are, according to recent findings, of little significance in this development.

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