Scientists have unraveled a mystery about why rare condors in the coastal redwood forests of central California are having problems reproducing. The culprit appears to be the long-ago banned pesticide DDT that lingers in our environment.

 

The condors that scavenge on dead carcasses are getting DDT from the tissue of their food sources, the scientists say.

Kelly Sorenson, executive director of Ventana Wildlife Society and a co-author of a new study on condors told the AP Press in an exclusive interview: “In science, rarely is anything definitive but we’ve established a strong link between ... DDT and eggshell thinning in California condors.”

The first signs of eggshell thinning in a condor nest was discovered in 2006.

During the following six years, scientists noticed condors feasting on dead sea lions, followed by fewer condor hatchings.

The scientists knew DDT lingers in the environment, so they began testing condor eggs, finding that 8 out of 16 cases of thinning were the result of DDT, which is also a known human carcinogen.

The researchers then concluded the sea lions accumulated so much DDT from a chemical dump that occurred in the 1970’s that took place repeatedly by the Montrose Chemical Company.

The sea lions were likely exposed when they migrated to the central coast from southern California.

Condor numbers plummeted in the early 1980's and have barely escaped extinction. The birds are considered 'magnificent' by many and they can climb to 15,000 feet. Their wingspan is 10 feet and they can weigh up to 30 pounds.

The California condors still face many challenges, the most recent of which is from DDT, a pesticide banned decades ago that lingers to harm our wildlife and environment. 

Reference: http://www.digitaljournal.com/article/358532