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The California Condor
The California condor has a wingspan of nearly ten feet - The largest of any North American bird. With a weight of up to 25 pounds, it is second only to the trumpeter swan as the heaviest bird on the continent. Lifting up their large bodies by flapping their wings requires a lot of energy, so California condors prefer to soar instead. When they land, they prefer cliffs, which makes takeoff easy. There are often thermal columns of rising air near cliffs that help them gain altitude.
Extinction for the California condor once seemed inevitable. By 1987 there were only 22 birds left in the world. Through captive breeding programs, the population has rebounded to over 400.
Decline of the California Condor
The California condor once roamed over much of North America. It is a scavenger, and once fed on the megafauna of North America. As humans entered the continent and hunted to extinction much of the megafauna, condor numbers began to fall By 1800, its range was restricted to the southwest and the west coast. The Lewis and Clark expedition sighted one in present day Oregon.
As humans began to settle the areas where the California condor lived, its numbers began to fall due to loss of habitat and hunting. Another factor affecting the condor population was DDT. Swiss chemist Paul Hermann Müller discovered DDT was an excellent insecticide in 1939. Soon it was widely used to control mosquitoes and and therefore malaria. Müller was awarded a Nobel Prize in 1948 for his discovery. Unfortunately, it was later discovered that DDT tended to concentrate in raptors and waterfowl, and caused their eggs to be thinner than normal. This lead to egg breakage and a lower rate of successful reproduction.
Another major factor affecting California condors is ingestion of lead shot. In its scavenging, it often consumes animals that have been hit by hunters, swallowing the lead shot, resulting in lead poisoning. California condors are more susceptible to lead poisoning than other vultures because of the very strong digestive juices in their stomachs. In 2007, California passed a law prohibiting lead ammunition in areas where condors reside. In 2013, the state passed a law to phase out lead ammunition by 2019.
Captive Breeding of the California Condor
It was decided that the only way to save the California condor from extinction was through captive breeding. By early 1987, all 22 wild birds had been captured. The breeding program was spearheaded by the Los Angeles and San Diego zoos.
Normally, condors only lay one egg and raise a single chick. Captive breeders were able to exploit the fact that if they removed the egg from the nest immediately after it was laid, the breeding pair would lay another. The condors would raise the second chick, while humans would have to raise the first chick. To make sure these chicks knew they were condors and not humans, they were fed by puppets which were made to look like condors.
Re-introduction of the California Condor
Before California condors were re-introduced into the wild, some re-introduction tests were done with female Andean condors, which are native to South America. This was a dry run for the later release of California condors. It was intended to uncover any problems with the re-introduction process without risking any of the very rare California condors. The tests were successful, and all the Andean condors were re-captured.
The original plan was to establish two wild populations, one in California and one in Arizona. Each population would have at least 150 condors and 15 breeding pairs. Condors were released into California in 1991-1992 and into Arizona in 1996. As the captive population grew, additional release sites were identified. These include two more sites in California and one in Mexico's Baja California. In 2014 a pair nested in Utah's Zion National Park. By late 2014 there were over 400 California condors, roughly evenly split between wild and captive birds.