Bird populations are considered to be a good indicator of the broad state of wildlife because birds occupy a wide range of habitats, they tend to be near or at the top of food chains and there is considerable long-term data on changes in bird populations which helps in the interpretation of shorter term fluctuations. The latest population indices for breeding farmland birds in England are published today, showing population trends relative to 1966 levels.
Please see Wild bird populations: Farmland birds in England 2009 (PDF 200 KB)