Neonicotinoids and decline in bird biodiversity in the United States

Neonicotinoid insecticides are being widely used and have raised concerns about negative impacts on non-target organisms. However, there has been no large-scale, generalizable study on their impact on biodiversity of avian species in the United States. Here we show, using a rich dataset on breeding birds and pesticide use in the United States, that the increase in neonicotinoid use led to statistically significant reductions in bird biodiversity between 2008 and 2014 relative to a counterfactual without neonicotinoid use, particularly for grassland and insectivorous birds, with average annual rates of reduction of 4% and 3%, respectively. The corresponding rates are even higher (12% and 5%, respectively) when the dynamic effects of bird population declines on future population growth are considered. The effects of neonicotinoids on non-grassland and non-insectivorous birds are also statistically significant but smaller, with an average annual rate of reduction of 2% over this period.