Common birds have higher abundances in croplands with lower pesticide purchases.

Field studies on pesticide impacts often lack detailed use data, struggle to disentangle their effects from agricultural intensification, and overlook the diversity of substances. Using a newly released French database on pesticide purchases, we investigated their relationship with bird abundances. We first validated that purchase data reflects environmental contamination by comparison with independent data on pesticide residues in surface waters. We then related the local purchases of 242 active substances to the abundance of 64 common bird species in croplands. Pesticide quantities correlated negatively with the abundance of 84.4% of the species, while we accounted for other aspects of agricultural intensification. We obtained similar results with a more integrative pesticide metric, combining quantity, toxicity and degradability of the substances. This result suggests a widespread negative impact of environmental contamination, extending beyond farmland specialists to common bird species foraging in croplands, with potential cascading effects within and outside these landscapes.