Terrestrial Scavenging of Marine Mammals: Cross-Ecosystem Contaminant Transfer and Potential Risks to Endangered California Condors (Gymnogyps californianus)

The critically endangeredCalifornia condor (Gymnogyps californianus) has relied intermittently on dead-stranded marine mammalssince the Pleistocene, and this food source is considered important for their current recovery. However, contemporary marine mammalscontain persistent organic pollutantsthat could threaten condor health. We used stable carbon and nitrogen isotope, contaminant, and behavioral data in coastal versus noncoastal condors to quantify contaminant transfer from marine mammalsand created simulation models to predict the risk of reproductive impairment for condors from exposure to DDE (p,p′-DDE), a major metabolite of the chlorinated pesticide DDT. Coastal condors had higher whole bloodisotope values and mean concentrations of contaminants associated with marine mammals, including mercury ( whole blood), sum chlorinated pesticides (comprised of ∼95% DDE) (plasma), sum polychlorinated biphenyls(PCBs) (plasma), and sum polybrominated diphenyl ethers(PBDEs) (plasma), 12–100-fold greater ...