Giant condors were successful and important components of the North American Pliocene and Pleistocene fauna, but began to decline about 13,000 years ago, with the Clovis culture and the decimation of mammoths, ground sloths, and other huge mammals. By 1985 a mere 27 California Condors (Gymnogyps californianus) remained, and the bold decision to take the entire population into captivity was made. The captive propagation program has been successful, increasing the population to more than 200 today. Nearly half of these birds have been released and live, semi-wild, in California and Arizona, including a wild-fledged bird from 2002. The species is still far from safe, though. The mortality rate, mostly from power-line collisions and lead bullet ingestion, still far exceeds wild births. Reintroduced condors show problematic behavior like extreme tameness, and because of lead poisoning, most of the Arizona birds had to be re-trapped for chelation therapy.