Maize fields as post-breeding habitat for songbirds: Influence of landscape composition, field margins, and weed infestation

Agricultural landscapes cover nearly half of Europe’s habitable land surface and play a central role in biodiversity restoration under the recently adopted EU Nature Restoration Law. Maize ( Zea mays ) cultivation has expanded rapidly worldwide and is generally considered of low value for birds during the breeding season. However, maize fields may provide critical resources for songbirds in late summer and autumn. Evidence for this remains limited because most existing studies are small in scale and short in duration. To identify factors shaping songbird presence in maize fields during late summer and autumn, we conducted a large-scale, long-term study (2016–2024) across 77 maize fields in Germany. We assessed bird abundance and species richness using mist-net captures and analysed their relationships with distance to field margins, surrounding habitat composition at multiple spatial scales, and levels of weed infestation. Bird abundance and species richness declined with increasing maize cover at the landscape scale. The influence of forest cover and woody structures varied substantially among species but had an overall positive effect on richness. At the field scale, higher weed infestation and proximity to field margins consistently enhanced bird numbers and richness. Our findings indicate that promoting heterogeneous landscapes, reducing distances to field edges, e.g., by farming small or narrow fields, and allowing moderate weed presence can increase bird abundance and richness in maize-dominated landscapes. These results provide farmers and policymakers with evidence-based guidance for aligning agricultural practices with the legally binding biodiversity restoration goals under the EU Nature Restoration Law.