Nationwide residues of organochlorine compounds in wings of adult mallards and black ducks, 1976-77.

Organochlorine residues in wings of adult mallards and black ducks were monitored nationwide during the 1976-77 hunting season. DDE was found in all samples. Levels were unchanged since the 1972-73 collections in all migratory routes except the Pacific Flyway, in which residue levels declined significantly. Dieldrin levels had not changed in any flyway and residues remained low. PCB levels declined significantly in the Atlantic Flyway but remained stable in other flyways. Heptachlor epoxide, mirex, endrin, hexachlorobenzene, and chlordane isomers were detected in low amounts in some samples.