Geographical and habitat differences in concentrations of copper, zinc and arsenic in eggshells of the Rook Corvus frugilegus in Poland

Abstract

Levels of copper, zinc, and arsenic were analyzed in the Rook Corvus frugilegus eggshells from 43 breeding colonies located in different parts of Poland. The average [95% confidence interval (CI)] level of copper was found to be 8.13 (0.64–15.62) ppm, of zinc 13.81 (7.99–19.62) ppm, and of arsenic 32.57 (25.60–39.54) ppm. The concentration levels of these metals varied widely in the surveyed shells, with the difference between extreme values being 90-fold for copper, 57-fold for zinc, and 36-fold for arsenic. General linear model (GLM) analysis revealed that the accumulation of copper in eggshells from urban rookeries was significantly higher than that in eggshells from rookeries in villages [average 19.31 (4.57–43.20) vs. 2.74 (2.36–3.12) ppm, respectively]. In comparison, the concentration of zinc in eggshells of urban colonies was only close to being significantly higher than that in eggshells of rural colonies (P = 0.07), and the arsenic levels in eggshells of rural and urban colonies were similar. No significant differences were found for any of the metals between rookeries located in the areas of intensive (western Poland) and extensive (eastern Poland) agriculture. Based on a comparison of our data with published data on arsenic contamination in different biota, including tissues and bird eggs of terrestrial and aquatic animals, the level of arsenic in Rook eggshells found in our study can be regarded as extremely high and is most likely due to the widespread use of pesticides containing arsenic.