Twenty condors were apparently poisoned with insecticide that has already killed two of the giant birds in the Chilean Andes cordillera, a veterinarian said Monday.
Condors have wingspans of up to 10 feet (3 meters) and can ride rising air currents for hours without stopping. But on Sunday they began crashing into the rocks high in the mountains near a hydroelectric plant.
Chilean officials and volunteers rescued 17 that were foaming from the beak and were too frail to fly. Another sick condor and two dead ones were found Monday. They were all taken to a veterinary clinic in the city of Los Andes, some 40 miles (70 kilometers) east of the capital, Santiago.
"The hypothesis is that they suffered organophosphate poisoning after they were exposed to insecticides used for agriculture," veterinarian Eric Savard, who has been treating them, told The Associated Press.
The 18 survivors are recovering with an antidote, antibiotics and saline solution, Savard said. They will remain under intensive care for 10 days.
The Andean condor is one of the largest flying birds in the world. Biologists estimate only a few thousand are in the wild.
Explore further: Blowfly protein key to terror poison antidote