During the winter of each year the Peregrine Fund staff in Northern Arizona attemps to capture every one of the wild condors in their area and test them for lead poisoning. The capture pen is located at the top of a cliff where the wild condors flock to catch updrafts. Once tested, the Condors that are free of lead poisoning are gathered in a holding area until all the captured birds have been tested. Once separated, healthy from afflicted, the healthy are released back into the wild. The gates of the jail are opened, and the birds rush to freedom.