Date: August 8, 2016
Source: University of California - San Diego
Biologists have discovered high levels of pesticides and other contaminants from marine mammals in the tissues of endangered California condors living near the coast that they say could complicate recovery efforts for the largest land bird in North America.
"Even though marine mammals are a potentially abundant food source for condors, they might not be that safe to eat," said Carolyn Kurle, an assistant professor of biology at UC San Diego and one of the senior authors of a study published this week in the journal Environmental Science and Technology that found high levels of persistent contaminants in California condors inhabiting the Central California coast when compared to inland condors.
California condors, vultures that feed on the carcasses of dead animals, were driven to near extinction in the 1980s, but their population has grown to over 400 birds today due in large part to the California Condor Recovery Program's efforts. However, condors are not out of the woods yet. Research has demonstrated that lead poisoning from feeding on carcasses contaminated with lead-based ammunition is the principal threat preventing condor recovery.
Some California condors that were re-introduced into the wild in recent decades as part of recovery efforts supplement their diet with carcasses of marine mammals, which are less likely than land-based animals to contain lead in their tissues.
Because marine mammal carcasses can be an abundant food source for coastal scavengers and are thought to have helped prevent the extinction of California condors at the end of the last ice age, 11,700 years ago, biologists welcomed this type of ocean-front dining as a likely boon to the condors' recovery efforts.