At least 20 condors have been poisoned mysteriously in the Chilean Andes mountains in recent weeks, and at least two of the endangered birds have died.
The birds were found foaming with the mouth and were too weak to fly, leading authorities to believe that they were poisoned with insecticide, Al Jazeera reports.
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Authorities suspect the birds were poisoned after eating the corpses of animals that had been intentionally poisoned in the area, according to the BBC, such as cattle or puma. Two foxes were also found dead.
"The hypothesis is that they suffered organophosphate poisoning after they were exposed to insecticides used for agriculture," said veterinarian Eric Savard to the Associated Press.
The eighteen surviving birds are being treated aggressively with a poison antidote, antibiotics and a saline solution, added the AP, and will be under intensive care for at least 10 more days.
The enormous Andean condor is among the planet's largest birds and among the heaviest that are capable of flight, weighing up to 33 pounds with a 10 foot-long wingspan, ideally suited for gliding through the windy heights of the Andes.
The birds tend to survive on large prey — either alive or deceased — and can live for as long as 75 years in captivity. Unlike many birds, they don't possess a larynx, meaning that they must communicate only in hisses, grunts, and clicks. BirdLife International estimates there is a surviving wild population of 6,500 individuals.
Here's a video of one of these enormous creatures: