Fig 1.
Change in NN application and change in farmland bird abundance for the UK between 1970 and 2014.
Bars: Pesticide Usage Survey data for annual weight (kg) of NN applied, moderated by a toxicity equivalency factor (TEF) to account for differences in the acute (Fig 1A) or chronic (Fig 1B) toxicity of each NN compound to birds (see Methods for details) [9]. Lines: breeding bird index for farmland birds based on 19 farmland indicator species (solid: unsmoothed trend; dotted: smoothed trend), reproduced from the Defra report ‘Wild bird populations in the UK, 1970 to 2014: Annual statistical release’ (Fig 2) [12]. NN: neonicotinoid.
Fig 2.
Overview of the manipulation process used to combine independent data sources to build the final model data frame.
AgC: EDiNA agcensus; BBS: breeding bird survey; BTO: British Trust for Ornithology; CTD: clothianidin; IMI: imidacloprid; JSA: June Survey of Agriculture; NN: neonicotinoid; PUS: Pesticide Usage Survey; TEF: toxicity equivalency factor (used to adjust for the differences in toxicity of each compound to birds); THX: thiamethoxam.
Table 1.
Availability of EDINA agcensus data for each crop type in England.
Table 2.
Reported concentrations of NN residues in avian dietary components.
Table 3.
Relative quantity of high-level residue food items in species diet and dietary exposure groups assigned to each species.
Fig 3.
Model estimates plus standard error bars for change in species population per unit (TEF-adjusted kg) of NN applied for each species included in the analysis.
Species are split by dietary exposure group and are ordered in each plot by rate of overall population change (‘BBS Trend’) according to BTO BBS data for England between 1995 and 2016 [37] with the largest population increase at the top and the largest decline at the bottom of each plot (see S1 Table for values). Species marked with (*) indicate significant (p<0.05) estimates of change in population per unit NN applied. BBS: breeding bird survey; BTO: British Trust for Ornithology; NN: neonicotinoid; TEF: toxicity equivalency factor.
Fig 4.
Distribution of β1 values (change in species population growth per unit [TEF-adjusted kg] of NN applied) obtained for each species across dietary exposure groups. The mean is represented by the black lines through the centre of each bar, the upper and lower quartiles are contained within the box and the range is represented by the whiskers. The estimate for turtle dove (Streptopelia turtur) is displayed as an outlier (represented by the single point) for the high exposure group. TEF: toxicity equivalence factor.