La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	What to do if the garbage runs out? 25-Year trend of gulls (Laridae) wintering in the Ruhr region
Auteurs :	Jochen Bellebaum, Auteur ; Andreas Buchheim, Auteur ; Joerg Nowakowski, Auteur ; Michael Sell, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (121(2-3) 2000)
Article en page(s) :	165-172
Résumé :	Since c. 1968 large numbers of gulls winter in the Ruhr district, a highly industrialized urban landscape, where gulls forage mainly on refuse dumps. While refuse production rose, January numbers of Herring Gulls exceeded 8,000 in 1989 - 1995. After 1992 several refuse dumps were closed, and roosts and flight lanes their importance, especially in the western part of the study area. The two major roosts in the eastern subregion held large numbers of gulls, and new relations between roots and feeding sites developed. A breakdown of refuse mass delivered at the remaining dumps since 1993 is expected to cause a decrease in numbers of gulls in the future. Until 1999 Herring Gulls compensated by utilizing other refuse dumps further from their roosts. Higher winter numbers in the study area were not associated with higher breeding numbers in the Wadden sea. Only a low proportion of organic waste delivered at the feeding sites was consumed by the gulls. Less than 5 % of organic waste fulfilled the energy requirements of the gulls at the largest roost at Kemnade reservoir.

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