Pesticide residues in wings of adult woodcock (Philohela minor) were used to monitor regional differences in a 1970-71 survey of DDT, DDE, TDE, dieldrin, mirex, and PCBs in Maine, New Hampshire, New York, New Jersey, Pennsylvania, North Carolina, South Carolina, Georgia, Lousiana, Michigan, and Wisconsin. In 1971-72, wings were sampled again to compare levels of organochlorine insecticide residues with those of the previous survey and to delineate differences in residue values between adult and immature woodcock. Three additional states, Massachusetts, Minnesota, and Vermont, and one additional organochlorine insecticide, heptachlor epoxide, were included in the second survey. Residue levels in the 1971-72 wings showed the same pattern as that observed in 1970-71: organochlorine insecticide residues were highest in wings collected in the southern states and in New Jersey; residues were lowest in samplings taken in the northern and midwestern states. Residues of DDT, TDE, and dieldrin in the 1971-72 wings were slightly lower than those found in 1970-71. DDE, PCB, and mirex residues were significantly lower (P<0.05, P<0.01, and P<0.01, respectively) in 1971-72. Wings of immature woodcock in Louisiana had significantly lower (P <0.05) mirex residues than did adult wings.
