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Résumé :
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In the Central European lowlands, the Black Grouse (Tetrao tetrix) is restricted to isolated remnant populations. Status reports have been published for some of them, but comparative analyses of Black Grouse dynamics across larger parts of the Central European range are missing. In this paper, we used published and unpublished historic information on local occurrences of Black Grouse in 37,000 km(2) of the German federal state of Lower Saxony to reconstruct changes in the species' distribution and abundance since the 1950s. We calculated population trends over 52 years (1955-2006) using software trends and indices in monitoring data (TRIM). Results showed two phases: an initial crash phase (1950s-1980s) when many local populations went extinct, and a recovery phase (1990s-2000s) for the remnants of the initial distribution. Differences in timing and extent of the crash were related at habitat type. Our study indicates that reconstructing population trends and distributions across larger geographic areas from historic data may enable comparative analyses of drivers of population dynamics across sites, and thus contribute to a better understanding of the causes of Black Grouse decline.
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