Organochlorine and mercury residues in eggs of the lesser kestrel (Falco naumanni) from a long term study in the eastern Mediterranean

Organochlorine and mercury residues were analyzed in unhatched eggs of the lesser kestrel (Falco naumanni) (2002-2012) in central Greece. Concentrations graded as ∑DDTs > ∑PCBs > HCB > ∑HCHs > ∑Chlordanes. Temporal declines were found in the concentrations of ∑DDTs, ∑HCHs and ∑Chlordanes but not in Hg, HCB and ∑PCBs. TEQs of PCBs and their degree of metabolisation showed no time trend. The reproductive parameters showed neither a temporal trend nor a significant year effect. No relationships occurred between the reproductive parameters per year and nest type (natural, artificial) with any of the contaminants analyzed except HCB influenced by year and clutch size. Low pollutant concentrations suggest that either lesser kestrels ranged across the year in unpolluted areas or may be caused by their short food chain. The low concentrations seem improbable to have affected the reproduction of these birds, although critical levels are still to be defined.