Restricted in the Neotropics to the mountains of extreme northern Baja, the massive California Condor is the largest North American vulture. One of the most endangered birds on the planet, it currently benefits from an ongoing reintroduction program throughout its range. In the 1980s, the last remaining wild California Condors were brought into captivity to take part in a captive-breeding program at the San Diego Zoo, which, through a collaboration of partners, has helped successfully reestablish the species in several locations in the western United States, including the site in northern Baja, Mexico. Condors take roughly 5-6 years to attain full adult head and plumage characters, with juveniles starting out darker and becoming progressively more colorful (head) and white (underwings) with each successive molt. Condors suffer mostly from indirect persecution in the form of lead poisoning, caused by foraging on carrion that has been shot with lead bullets.