condors

Before the training was introduced, 66% of set-freed condors died of electrocution.

California condors are north America's largest birds, with wind-length of up to 3 meters.

California condors attract researchers' interest because they almost died out in the 1980s.

California condors attract researchers' interest because they had to be bred in the wild.

In the late 1980s, the last few condors were taken from the wild, and there are now more than 150 flying over California and nearby Arizona, Utah and Baja in Mexico.

Researchers have found electrical lines are big killers of California condors.

Rideout's team thinks that the California condors' average survival time in the wild is now just under eight years.

So condors with high levels of lead are sent to Los Angeles zoo, where they are treated with calcium edta, a chemical that removes lead from the blood over several days.

The annual death rate for adult condors has dropped from 38% in 2000 to 5%.

The average survival time of condors is satisfactory.

The passage shows that the efforts to protect condors have brought good results.

When condors eat dead bodies of other animals containing lead, they absorb large quantities of lead.