California condors (in Big Sur) still at risk from DDT

Joel Pratt from the Extinction Countdown blog brings up an astonishing fact. More than four decades after DDT was banned, California condors in the Ventana/Big Sur area still struggle (with an unfortunate lack of success) to produce viable eggs. Pratt writes:

The Ventana Wildlife Society (VWS), which manages the California condor (Gymnogyps californianus) reintroduction program in the coastal Big Sur region, first began to suspect in 2006 that DDT was affecting the big birds. Two captive-born condors successfully nested in the wild then for the first time in that region. The birds mated and laid eggs, but they soon cracked and the nest failed. An examination revealed that the shells were so thin that they didn’t even resemble normal condor eggs.

Since that time many more eggs have been laid in the region but 12 out of 16 condor nest sites failed between 2007 and 2009. Fragments of shells—all visibly thin—were recovered from those sites. Meanwhile, the condors released 650 kilometers farther south have enjoyed a 70 to 80 percent hatching success rate.

Checked with Pratt: yes, the research says that it's only condors that feast on dead sea lions are are suffering this problem. So Ventura County condors need not fear that particular fate (although microtrash, lead poisoning, and reduced habitat remain huge issues, needless to say).

Great commons pic from Gregory Smith:

California-condor-Gregory-Smith

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