DDE DECREASES IN PLASMA OF SPRING MIGRANT PEREGRINE FALCONS, 1978-94

Mean p,p'-DDE (DDE) residues in plasma of combined adult and subadult female peregrine falcons (Falco peregrinus) decreased significantly in spring migrants captured at Padre Island, Texas, between 1978 and 197 9 (1.00 mu g/g wet wt), 1980 (0.57), 1984 (0.50), and 1994 (0.34). No other organochlorine pesticides were detected (detection limit, 0.02 m u g/g) in 1994. Mirex, oxychlordane, dieldrin, heptachlor epoxide, and the parent material DDT were routinely found in plasma samples in ear lier years. Polychlorinated biphenyls (PCBs) were found in 75% of the adult females in 1994, but PCB data collected in 1984 were not compara ble. The decrease in organochlorine pesticide residues was associated with peregrine population increases in the Arctic and elsewhere in Nor th America. The arctic peregrine (F. p. tundrius) was removed from the list of Threatened and Endangered Species by the U.S. Fish and Wildli fe Service in 1994. Satellite telemetry and plasma sampling provide ne w insight into continuing sources of DDE and PCBs. Chemicals that repl aced organochlorine pesticides require additional investigation in Nor th and South America.