Patterns of organic contaminants in eggs of an insectivorous, an omnivorous, and a piscivorous bird nesting on the Hudson River, New York, USA.

Belted kingfisher (Ceryle alcyon), spotted sandpiper (Actitus macularia), and tree swallow (Tachycineta bicolor) eggs were collected in 2004 from the upper Hudson River, New York, USA. This area is one of the most polychlorinated biphenyl (PCB)-contaminated locations in North America. Multivariate analyses indicated among species differences in the concentration and composition of PCB congeners, polychlorinated dibenzo-p-dioxin (PCDD), and dibenzofuran (PCDF, PCDD-F when combined with PCDDs) congeners, and chlorinated pesticides. Total PCB concentrations followed the typical food chain biomagnification paradigm of higher concentrations in piscivorous bird eggs and lower concentrations in eggs of species that feed at lower trophic levels. Concentrations in the insectivorous swallows (geometric mean = 6.8 µg/g wet wt) were approximately half the concentrations present in the piscivorous kingfisher (11.7 µg/g) or omnivorous sandpiper (12.6 µg/g). In contrast, PCB toxic equivalents (TEQs) were higher in swallows (1,790 pg/g wet wt) than in either kingfishers (776 pg/g) or sandpipers (881 pg/g). This difference can be mainly attributed to higher PCB77 concentrations in swallows relative to the other two species. Also contrary to the accepted food-chain paradigm, the sum of PCDD-F concentrations and the sum of their TEQs were higher in swallows than in either sandpipers or kingfishers. Metabolic pathway differences in the respective food chains of the three species probably accounted for the differences observed in PCB TEQ, total PCDD-F, and PCDD-F TEQ concentrations among species.