Organochlorine residues and autopsy data from bald eagles 1966-68

Sixty-nine bald eagles found moribund or dead in 25 States during 1966-68 were analyzed for pesticide residues. Residues of polychlorinated biphenyls and DDE were detected in all samples of eagle carcasses; residues of dieldrin were detected in 68 and residues of DDD in 64; DDT, heptachlor epoxide, and DCBP were detected less frequently. Eight specimens had levels of dieldrin in the brain within the lethal range, and another probably died of DDT poisoning. Autopsy revealed that illegal shooting was the most frequent cause of mortality of these eagles; electrocution, impact injuries, probable lead poisoning, and infectious avian diseases were other causes of mortality.