Research: Declines in insectivorous birds are associated with high neonicotinoid concentrations
July 9, 2014
Abstract:
Recent studies have shown that neonicotinoid insecticides have adverse
effects on non-target invertebrate species1–6. Invertebrates constitute
a substantial part of the diet of many bird species during the breeding
season and are indispensable for raising offspring7.We investigated
the hypothesis that the most widely used neonicotinoid insecticide,
imidacloprid, has a negative impact on insectivorous bird populations.
Here we show that, in the Netherlands, local population trends
were significantly more negative in areas with higher surface-water
concentrations of imidacloprid. At imidacloprid concentrations of
more than 20 nanograms per litre, bird populations tended to decline
by 3.5 per cent on average annually. Additional analyses revealed that
this spatial pattern of decline appeared only after the introduction
of imidacloprid to the Netherlands, in the mid-1990s. We further
show that the recent negative relationship remains after correcting
for spatial differences in land-use changes that are known to affect
bird populations in farmland. Our results suggest that the impact of
neonicotinoids on the natural environment is even more substantial
than has recently been reported and is reminiscent of the effects of
persistent insecticides in the past. Future legislation should take into account the potential cascading
effects of neonicotinoids on ecosystems.
