Valuing the agro-ecosystem services of birds can quantify the economic contribution of biodiversity and inform agricultural and conservation policies. Yet, no large-scale, generalizable study has assessed the contribution of birds to crop yields. Using county-level panel data for breeding birds in the United States over 1997-2014, we estimate the effects of grassland bird, insectivorous bird, and endangered bird biodiversity on corn and soybean yields in the presence of neonicotinoid use. We find that the yield effects vary by bird group: grassland birds contribute positively to corn and soybean yields, insectivorous birds contribute negatively, and endangered birds show no statistically significant effect. Neonicotinoid use diminishes both the beneficial and detrimental influences of birds on crop yields. When evaluated at sample means, grassland birds contribute to 11.52% of corn yield (an economic value of $9.3 billion per year), while their contribution to soybean yield is statistically insignificant. Neonicotinoid use contributes to 3.82% of corn yield and 7.02% of soybean yield, corresponding to annual economic values of $3.1 billion and $4.1 billion, respectively. Were grassland birds to become extinct, neonicotinoid use would need to increase by 219.43% to maintain current corn yield. Conversely, if neonicotinoid use were banned, then a 32.93% increase in grassland bird population could offset the resulting reduction in corn yield.
