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La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	Development of populations of meadow waders breeding in Germany - results of a new monitoring approach for scarce bird species
Auteurs :	Hermann Hoetker, Auteur ; Heike Jeromin, Auteur ; Johannes Melter, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (128(2) 2007)
Article en page(s) :	49-65
Résumé :	A high proportion of bird species breeding in Germany has population sizes that are too small to be covered adequately by the monitoring of common bird species. On the other hand, many of these species are too common to be included in monitoring schemes for rare birds. In this paper we use \'meadow waders\' as an example to introduce a monitoring scheme particularly designed to fill the gap between the monitoring schemes for common and rare birds - a site-based monitoring scheme. The scheme is based on counts in previously defined sites. Both regular counts and occasional counts can be incorporated. Wherever possible the counting sites of already existing schemes (e. g. for waterbird counts or for Natura 2000 sites) are incorporated. The new monitoring scheme thus can make maximum use of already existing programmes, and the efforts for additional counts therefore can be reduced. Data are analysed by the software TRIM. In order to test the scheme we collected 26,258 data sets for Oystercatcher, Lapwing, Dunlin, Ruff, Snipe, Black-tailed Godwit, Curlew and Redshank breeding in Germany in 1960-2004. Altogether 2,177 counting sites were defined. Nearly all breeding sites of Dunlin, Ruff and Black-tailed Godwit and most breeding sites of Curlew and Redshank were included. Whenever possible, population indices and trends were calculated separately for different habitats/regions: Wadden Sea islands, North Sea coastal salt marshes, clay marshes on the North Sea coast,.Baltic coast, remaining inland sites. The data usually allowed to describe the population developments since 1990, occasionally earlier.The populations of Lapwing, Dunlin, Ruff, Snipe, Black-tailed Godwit und Curlew breeding in Germany significantly declined since 1990. Implying that the trends do not change, Dunlin and Ruff will stop breeding in Germany within the next years. Numbers of Black-tailed Godwit and Snipe dropped by more than half since 1990. The Oystercatcher population increased until 1996, but significantly decreased thereafter. The Redshank is the only species with a slightly positive trend. Trends differed between habitats and regions. On the Wadden Sea islands all five species increased their populations. On the mainland North Sea salt marshes two species each declined and increased. On the clay marshes most species had negative trends, and on the Baltic coast and in the rest of inland Germany all species declined. Population developments of Dunlin, Ruff and Black-tailed Godwit given in the paper match published data quite well. The analysis presented here shows that Curlew and Redshank were somewhat more common in Germany than hitherto estimated.

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