Authors: Roilo, Stephanie; Cord, Anna;

Agri-environment schemes, ecological focus areas and organic farming are the main tools of the Common Agricultural Policy to counteract the dramatic decline of farmland biodiversity in Europe. However, their effectiveness seems to vary depending on the regional environmental and land-use context. Using ensemble species distribution models and field-level land-use information from the Integrated Administration and Control System, we investigated the effects of five groups of measures (buffer areas, cover crops, extensive grassland management, fallow land and organic farming) on the occurrences of 11 farmland bird species in three study regions in the Czech Republic, Germany and Spain. Despite differences in environmental conditions and land-use context among the three study regions, the majority of species were positively associated with all measures in all regions, except for the German case study, where organic farming had contrasting responses across species. Variable importance scores were low in all regions for all measures compared to climatic, topographic and land-cover variables; and the difference in modelled habitat suitability between scenarios with and without agri-environment measures was limited. We argue that the low uptake of these measures by farmers, despite their overall positive effects on habitat quality, compromises conservation efforts for farmland birds in European agroecosystems.