An Oregon Zoo Foundation-funded study has cracked the mystery of why some California condor eggs don’t hatch.
Forty-year-old underwater chemicals are to blame, the study’s authors found.
Sea lions have been feeding near a Superfund site in Southern California, and in the process ingesting the banned pesticide DDT, said the Ventana Wildlife Society’s Joe Burnett, co-author of the study. After the sea lions die, condors feed on their carcasses — and consume the chemical in the process. DDT has long been known to weaken bird eggshells.
“Marine mammals can act as vectors for a variety of contaminants,” Oregon Zoo deputy conservation manager David Shepherdson said in a statement.
In 2014, the zoo foundation plans to fund more research investigating how toxins in marine mammals affect birds.