The Publications Warehouse does not have links to digital versions of this publication at this time
Residues of DDE in wild black duck (Anas rubripes) wings or eggs are lower now than they were in the 1960s, and the mean shell thickness of eggs collected in 1978 has recovered to the pre-DDT use thickness. Mean DDE residues (ppm, wet wt) for eggs were: 1964, 2.93; 1971, 1.22; 1978, 0.65. Average DDE residues in wing pools were: 1965-66 and 1966-67 combined, 1.23; 1969-70, 1.42; 1972-73, 0.35 and 1976-77, 0.39. The threshold level of DDE in black duck foods for causing shell thinning is about 0.6 ppm, wet wt. Captive black ducks fed this dietary amount laid eggs with shells that were lighter in wt (-11.3%; P < 0.05) and with a reduced Thickness Index (-9.6%; P < 0.05) as compared with shells of untreated black ducks. Shell thinning-(-8.0%) was not lower (P > 0.05) for DDE-dosed birds, but this was caused by 1 unusually thin (0.283 mm) eggshell from a control hen. Our ad libitum diet, which equals the amount of DDE detected in some black duck foods, resulted in a mean DDE egg residue that was 4-6 ppm above the highest DDE residues detected in field-collected black duck eggs in 1964 (12.1 ppm) and 1971 (14.0). A comparison of documented effects of DDE in captive black ducks with DDE residues reported from wild black duck wing pools and eggs collected during 1964-78 suggests that reproductive success in wild black duck females was impaired in the 1960s and perhaps earlier.
Additional Publication Details
Black ducks and DDE: Review and status
Transactions of the Northeast Section of the Wildlife Society, Annual Fish and Wildlife Conference