In three species of waterbirds nesting along the Hudson River, 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. In contrast, PCB toxic equivalents (TEQs) were higher in tree swallows than in either belted kingfishers or spotted sandpipers. 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.
Custer, C.M., T.W. Custer, and P.M. Dummer. 2010. Patterns of organic contaminants in eggs of an insectivorous, omnivorous, and piscivorous bird nesting on the Hudson River, NY, USA. Environ. Toxicol. Chem. 29:2286-2296. "Any opinions presented are those of the principal investigators and not the position of the United States or the Hudson River Trustees."