Changing the fallow paradigm: A win-win strategy for the post-2020 Common Agricultural Policy to halt farmland bird declines

1. Farmland bird populations have declined sharply due to agricultural intensification. In Europe, these negative population trends have been linked to the loss of semi-natural vegetation types, particularly fallow land. The work of Sanz-Perez et al. (2019) has far-reaching implications for the conservation of farmland bio-diversity. We argue that it supports a new paradigm for the understanding and management of fallows that should be integrated into the forthcoming post-2020 Common Agricultural Policy (CAP). 2. Following the abolition of mandatory set-aside by the European Union in 2008, fallows declined steadily in Europe until 2015, when the CAP implemented greening measures. These restored the requirement to leave 5% of arable land as ecological focus areas (EFAs) to enhance biodiversity. While fallows are one of the most beneficial forms of EFA for farmland birds, farmers prefer the less conservation effective planting of nitrogen-fixing and catch crops (currently more than 70% of EFAs). CAP incentives have been insufficient to make unproductive EFAs such as fallows more attractive to farmers. 3. Sanz-Perez et al. (2019) evaluated the impact of different fallow land management practices on the abundance of specialist farmland birds. They concluded that extensive practices - such as tilling or shredding once or twice per year before the breeding season - were more beneficial to these declining species than leaving fallows unmanaged and recommended their incorporation into agri-environment schemes. But such schemes have had low uptake, and thus a limited potential to drive the widespread recovery of farmland birds at either national or European levels. The post-2020 CAP, currently under development, should integrate simple fallow management practices within new conditionalities or eco-schemes to address this problem. 4. Synthesis and applications. The loss of fallow land underlies the decline of farmland birds. The post-2020 CAP must overcome past mismatches between incentives to farmers and biodiversity benefits and increase farmers' uptake of the most beneficial options for biodiversity, including fallows. Promoting light management of fallow land within the new CAP eco-schemes is a win-win strategy because it would simultaneously allow farmers to continue extensive weed control and enhance habitat quality for farmland birds.