High toxic levels found in condors
The rebound of the California condor, back from near-extinction but still endangered, could be imperiled by the stubborn remnants of a banned pesticide in the coastal environment, according to new research by a team of San Diego researchers.
Condors in coastal California had seven times more contaminants in their blood than their inland counterparts, according to the researchers. The finding could be linked to the recent discovery of thousands of barrels of DDT that had been in the ocean off the coast of Los Angeles. The analysis was done by a team of researchers with San Diego State University and the San Diego Zoo Wildlife Alliance
who found a broad set of DDT-related compounds in the blood of condor fledglings and marine mammal blubber.
“It’s not great news for California birds,” said Christopher Tubbs, associate director of reproductive sciences for San Diego Zoo Wildlife Alliance.
Yet the study found the Gulf of California in Mexico could be a more hospitable environment for these majestic birds, the largest in North America with wing spans nearing 10 feet.
Marine mammals, a key food source for these iconic scavengers, had nearly 150 times less of one specific chemical linked to DDT production in their blubber in Baja compared with coastal California samples, Tubbs said. Contaminants overall were three-tofour times lower in dolphins, sea lions and other marine mammal carcasses washed ashore in Baja compared with southern California.
Tubbs said the data could help shape policies for where wildlife biologists reintroduce condor fledglings in the wild.
DDT was banned in the 1970s amid mounting evidence the pesticide was deadly to wildlife and harmful to people, but its chemical compounds have remained in the environment. Among other harms, it can cause the egg shells of birds to become thin.
DDT has been blamed for the dramatic decline in bird populations decades ago, condors among them.
The number of condors had plummeted to just 22 in the 1980s but has risen to more than 500 with persistent support of breeding and reintroduction programs from Northern California to Baja California.
This year, members of the Yurok Tribe released four condors into the wild in Humboldt County in a bid to reestablish
the birds in Northern California, where they have not flown free for more than a century.
Before they were reintroduced, researchers tested the blood of marine mammal carcasses along Humboldt County beaches to determine whether there were significant levels of DDT in the environment.
Researchers found those remnant chemicals associated with the pesticide to be low compared with other areas where the birds were being reintroduced.