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2014-07-17 Hallmann, C.A. (Radboud University); Foppen, R. P. B. (Sovon, Dutch Centre for Field Ornithology); Turnhout, C. A. M. van (Sovon, Dutch Centre for Field Ornithology); Kroon, H. de (Radboud University); Jongejans, E. (Radboud University) 10.17026/dans-x9b-azy5
In our paper ‘Declines in insectivorous birds are associated with high neonicotinoid concentrations’ (Nature 511:341-343, July 2014) we analyze the spatial distribution of population trends (over the period 2003-2010) of 15 insectivorous bird species that occur in agricultural areas in the Netherlands. We related the trends of 1459 populations with interpolated concentrations of the pesticide imidacloprid in surface waters (with a maximum distance of 5 km between the location of the bird population trend and the nearest location of an imidacloprid concentration measurement), and found a strongly negative correlation.
In this repository we provide a detailed R-script (‘analyses.R’) with these statistical analyses. We also archive the bird population trend data underlying the analyses in the paper. The data can be found in three different files:
- ‘Lamdas2003_2010.csv’ contains the data for the main analyses in which the bird population trends are related to imidacloprid concentrations and to other changes in the agricultural landscape;
- ‘Lamdas2003_2010_distance.csv’ contains a larger set of bird population trends over the same time period and includes distance data to the nearest imidacloprid measurement (these data are used for the robustness check used to confirm that our conclusions are not influenced by the choice of maximum distance [varying between 1 and 25 km]); and
- ‘Lamdas2Periods.csv’ which contains the subset of bird population trends for which we could compare the trends between the period 2003-2010 and 1984-1995 to confirm that the observed spatial distribution of bird population trends did not exist already before the introduction of imidacloprid.
The following variables are included in these data records of the species-plot-specific population trends: English and scientific species names, intrinsic population growth rates (logLamda), the mean density of birds in the plot, spatial coordinates (X, Y; Dutch RD coordinate system), natural logarithm of interpolated imidacloprid concentrations, distance to the nearest imidacloprid measurement, and eight additional landscape variables. These landscape variables were the municipality-specific changes in areas of fallow land, winter cereals, maize, greenhouses, bulbs, natural habitat (e.g. marshes, reed beds, heathlands, forests) and urban areas, for which we calculated the difference in proportional surface coverage between two successive time periods (1995/1996 and 2006/2007). The eighth landscape variable was the change in the application of Nitrogen fertilization (N in kg/ha).
All computations were carried out in the R environment for statistical computing (R Core Team, 2013. R: A Language and Environment for Statistical Computing. R Foundation for Statistical Computing, Vienna, Austria. http://www.R-project.org/.) with the aid of packages gstat (Pebesma, E.J., and C.G. Wesseling. 1998. Gstat: a program for geostatistical modelling, prediction and simulation. Computers & Geosciences 24:17–31.) and nlme (Pinheiro, J., D. Bates, S. DebRoy, D. Sarkar, and R Core Team, 2013. nlme: Linear and Nonlinear Mixed Effects Models.).