Ergebnisse des DDA-Monitoringprogramms, Teil II: Bestandsentwicklung von Waldvögeln in Deutschland (original) (raw)
The German Common Birds Census, which runs since 1989 and is based on territory mapping and point counts, provides reliable data (TRIM index curves) on the population changes of 52 German forest bird species. Despite free choice of plots and routes, only a quarter of these species shows significant differences in annual changes or overall trend of the index curves derived from the two different field methods. These differences could be successfully interpreted by analysis of sub-samples (post-hoc stratification). Concerning the annual population changes, 11 partly or short-distance migrants turned out to be sensible against severe winters, most pronounced in the Wren. Negative correlations between severe winters and the population changes of the long-distance migrant Wood Warbler are probably caused by delayed growth of the ground vegetation in spring. Positive responses to severe winters in 11 (optional) seed-feeding residents and partly migrants as well as four long-distance migra...
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