Today, the California condor is regarded as one of the rarest birds in the world. In Pleistocene times, condors ranged from Canada to Mexico, across the southern United States to Florida, and north on the east coast to New York. During that period, condors were a common resident of the Grand Canyon judging by bones, feathers and eggshells found in caves where they once nested. A dramatic range reduction occurred about 10,000 years ago, coinciding with the late Pleistocene extinction of large mammals such as mastodons, giant ground sloths, camels, and sabre tooth cats that condors fed on.
By the time Europeans arrived in western North America, condors had retreated to a stronghold along the Pacific coast from British Columbia to Baja California. The birds managed to maintain a strong population until shooting, egg collecting, poisoning by cyanide traps set for coyotes, power line collisions, general habitat degradation, and especially lead poisoning began to take a heavy toll. Lead poisoning from ingesting fragments of lead ammunition in the carcasses and gut piles they feed on remains the greatest threat to California condors today.
From the 1880s to 1924, there were scattered reports of condors in Arizona. But by the late 1930s, no condors remained outside of California and by 1982, the total population had dwindled to just 22 birds. Extinction loomed.
The California condor was placed on the federal endangered species list in 1967. Critical habitat was identified and mortality factors were studied. The U.S. Fish and Wildlife Service began a captive breeding program in 1983.