In recent decades, many of Germany's animal populations in agricultural landscapes have experienced sharp declines, both in terms of the number of species and the number of individuals. Fallow land is considered an effective measure to slow this decline. Researchers from the Thünen Institute, the University of Göttingen and the Dachverband Deutscher Avifaunisten (DDA) have investigated the correlation between the proportion of fallow land and the number and abundance of farmland birds over a nine-year study period.