Inter-colony differences in hepatic element concentrations of European flagship farmland bird, the Rook Corvus frugilegus, breeding in rural habitats in East Poland

Concentration of 12 trace elements (Cd, Cr, Cu, Hg, Mg, Mn, Ni, Pb, Se, Sr, V, Zn) in livers of 29 adult Rooks Corvus frugilegus breeding in agriculture landscape in the Lublin Voivodship (South-East Poland) were determined. The presented study aimed to compare elements concentration between colonies and sexes, as well as to determine common sources of metals and elements. Analyses for particular elements revealed exclusively one significant effect of colony location on hepatic concentration of cadmium. No sex differences were found what may be explained by the lack of diet differences and/or low sequestration of the surplus of non-essential elements in females to the eggs during their formation. Bioaccumulation of Cd appears to be strongly site-dependent. The highest concentrations of this element were recorded in rookeries located in big size farms with large monocultural cultivated areas with intensive use of fertilizers. Cluster analysis suggests that fertilizers and other agrochemicals, are likely sources of tissues contamination in species foraging on soil invertebrates. The intense agriculture production with regular use of agrochemicals, promoted nowadays may lead to pronounced absorption of toxic elements by species associated with farmland.