p,p'-DDE, polychlorinated biphenyls, and endrin in oldsquaws in North America, 1969-73.

Organochlorinated compounds were monitored in oldsquaws (Clangula hyemalis) and their food from Lake Michigan between October and May, 1969-72; in adult oldsquaws, eggs, young, and food from northwest Hudson Bay in 1971; and in oldquaws from five wintering areas other than Lake Michigan in 1971-73. Analyses were conducted on 300 carcasses, 14 wings, 29 gullet samples, and 11 clutches. Average residues in carcasses from Lake Michigan ranged from 4 to 107 ppm PCBs, 2 to 42 ppm DDE, and less than 0.1 to 0.7 ppm endrin. Differences in DDE levels occurred between several sex and age classes during December on Lake Michigan; these differences were not apparent in the spring. Increases in DDE and PCB residues for oldsquaws occurred on Lake Michigan between December and May. DDE residues in the wing and carcass were significantly correlated. Residues were relatively low in oldsquaw foods from Lake Michigan; concentration factors between the food and the ducks varied between 1X and 22X, depending on the date and compound. Organochlorinated residues were lower in Arctic than in Lake Michigan food samples. DDE in paired male and female oldsquaws was highly correlated, as was DDE in females and clutches. Eggshell thickness had declined 4.5% compared with eggs collected before 1947. Residues were higher in oldsquaws wintering on the Great Lakes and lowest in oldsquaws from coastal areas.