Dioxin Showing Up In Falcon Eggs
Dioxin Showing Up In Falcon Eggs
Jul. 26, 1989
GRANTS PASS, Ore. (AP) _ An alarming number of peregrine falcon eggs failed to hatch this year in southern Oregon and northern California, say scientists who fear chemical contamination is to blame.
Falcon eggs taken from the same area last year after they failed to hatch found deadly chemicals, including dioxin, said Joel ''Jeep'' Pagel, a U.S. Forest Service falcon specialist.
Tests on eggs laid this year are incomplete, but Pagel said Tuesday that he fears the chemicals are killing the embryos before they mature enough to hatch.
''At the beginning of the year, I had 28 aeries (falcon nests) I monitored,'' Pagel said from his office in Happy Camp, Calif. ''I had 22 of those 28 aeries fail this year, which is astronomical. It's a little above 78 percent.''
Pagel normally finds and bands 25 or 30 young falcons a nesting season. This year he found only 11. This year's jump in nesting mortality was the biggest Pagel has seen since he began watching the birds in 1983.
Damage to falcon eggs by the now-banned pesticide DDT reduced the population to just two pairs in California and none in Oregon by 1975. But since then, the population has recovered to the point California has 85 pairs and Oregon has 13 pairs.
Dioxin, a deadly chemical found in the Vietnam-era herbicide Agent Orange and used in industry, has been found in peregrine falcon eggs from the central coast of California the past couple of years. But Pagel thought northern California and southern Oregon birds were isolated enough to escape contamination.
''So much for our little haven,'' he said.
Pagel turned over seven of the eggs that failed to hatch this year to Wally Jarman, a graduate student at the University of California, Santa Cruz, for testing. Results are due in September.
Last year, Jarman's tests on failed eggs found dioxin and related chemicals, as well as a compound related to cancer-causing PCBs. PCBs, or polychlorinated biphenyls, come from a fire retardant that used to be added to the oil in electrical transformers.
Jarman has found the same chemicals in failed peregrine falcon eggs laid between 1983 and 1988 in nests in the Big Sur area on California's central coast.
In the Big Sur eggs, he also found DDE, which is formed in the tissues of animals exposed to DDT. DDT hasn't been used in this country since 1972, but it is extremely slow to break down in the environment, and it lingers in the animals who consume it.
''The big question was why such a pristine area would have high levels of pesticides, PCBs and dioxins,'' Jarman said.
Jarman said the poisons don't seem to be coming from any one source. Since the falcons are predators, they accumulate chemicals consumed by their varied prey, which ranges from small birds like the titmouse to larger ones like ducks and gulls.
Brian Walton, coordinator of the Predatory Bird Research Group at the University of California, Santa Cruz, theorized that the aging of the birds Pagel has been watching may account for their newfound nesting failure.
''It may be that after they are five or six years old they build up sufficient levels (of toxic chemicals) that they start failing,'' Walton said. ''They can breed while they're young, but when they get old, they fail.