Habitat-specific bird trends and their effect on the Farmland Bird Index

Farmland birds in Europe have declined in numbers from the last decades, as reflected in the Farmland Bird Index (FBI), a multi-species indicator of population trends adopted by the European Union. Some of these farmland bird species breed to a varying degree also in non-farmland habitats; however, the indicator is calculated using trends estimated from all birds counted of each species, irrespective of habitat. Consequently, when interpreting indicators of farmland birds, it is important to know the influence of including the trends of the populations in non-farmland habitats. We estimated national and regional bird–habitat relationships and population trends of 14 of the species included in the Swedish version of FBI. Bird data came from the Swedish Bird Survey (1996–2008) including 716 separate routes, and detailed habitat data came from the Swedish Board of Agriculture (1999–2008).