Impacts of Toxins on the California Condor, Gymnogyps californianus: A Synthesis of Information.

Students at Dominican University of California are conducting a literature synthesis involving detrimental effects of known toxins on the California condor. The students are evaluating published literature to confirm a hypothesis; Condors feeding on dead terrestrial animals have toxic contaminant loads different from those of contaminants found in condors feeding on carcasses of marine animals. Terrestrial food items are generally dead grazers: low trophic level herbivores such as deer or cattle. In contrast marine carcasses, such as beached large fish and marine mammals, are high trophic level feeders, containing a greater content of biomagnified toxins. This presentation addresses toxins such as: lead, mercury, and pesticides, including rodenticides and polychlorinated biphenyls. The California condor was on the edge of extinction in the wild approximately fifty years ago. The US Fish and Wildlife Service listed it as an endangered species in 1967. Twenty years later the last remaining wild condors were captured. Protected chicks were reared and captive condor populations increased. Many captive condors were released into historic habitats in the wild where they are currently monitored, protected, and screened for toxins. These restoration efforts have resulted in increased numbers, but whether populations will continue to grow without continued intensive management is unknown. Condor health issues are due to many factors; Lead is the primary toxin affecting their long-term success. Documented impacts of toxins in condors include blood poisoning and eggshell thinning. Additional potential health problems associated with contaminants in condors include altered behavior, neurological pathologies, endocrinological disruptions, immunological damage, and anemia