Agricultural policies and biodiversity: impact of the CAP greening on bird abundance and diversity in France

In 2013, the European Union Common Agricultural Policy introduced a set of compulsory greening measures in its subsidies scheme in order to achieve environmental goals. We analyse the impact of this reform, and particularly the definition of Ecological Focus Areas (EFA), on bird diversity in France. We match bird observations from the French Breeding Bird Survey (BBS) to parcel level information on agricultural land use and type of crops. We exploit the heterogeneous exposure of bird observation sites to the reform depending on their ex-ante extent of arable area in a continuous difference-in-differences approach. We find evidence of an increase in overall bird abundance after 2015 in sites with a higher ex-ante proportion of arable land, driven by a small number of generalist species, and no impact on species richness and phylogenetic diversity. A decomposition by diet type suggests that vertebrate eaters were positively impacted by the reform. By contrast, cropland species experienced the most dramatic decline after 2015 in sites with a higher share of arable area. Estimations of the dynamic effects of the reform suggest that the observed positive effects on bird abundance were limited to the first two years after its implementation. Based on observational data, our findings confirm previous concerns regarding the effectiveness of the 2013 reform in preserving biodiversity.