California condor No. 321 has taken an historic flight, flying across the United States and Mexico border Wednesday. The last documented sighting of a California condor in San Diego County was in 1910.

“The aim of the California Condor Recovery Program is to unite the southern region of the condor’s range in Mexico with the birds in California,” said Mike Wallace, Ph.D., Zoological Society of San Diego scientist and the California Condor Recovery Program team leader. “This first flight into San Diego County could be the beginning of the connection between these two populations.”

The female bird flew from the California condor release site in the Sierra San Pedro de Martír National Park in Baja California, Mexico along the Sierra Juarez mountain ridge Tuesday. She flew past the U.S. border along the Jucumbra Mountains Wednesday and was last documented in the Anza-Borrego area through GPS. Condor 321 was hatched at the San Diego Zoo’s Wild Animal Park and released in 2005.

The Zoological Society of San Diego, in cooperation with U.S. Fish and Wildlife Service and the Mexican government, began a reintroduction program in Baja California, Mexico in 2002 led by Dr. Wallace through the center for Conservation and Research for Endangered Species (CRES), the Zoological Society’s research division. With condor No. 321 now in the U.S., 10 condors are flying free in Mexico, with five birds waiting for release next month.

California condors disappeared from Mexico in 1937. The goal of the California Condor Recovery Program is to establish two independent populations of California condors. Condors released in Central California and the Baja California birds are expected to eventually become one population. To date, the Central California birds have flown as far south as the San Bernardino mountains. The second population of birds is being established in Arizona.

The public can help researchers if a sighting is made by e-mailing the location of the condor, its identifying tag number, and what the bird was doing to the Zoological Society at condors@sandiegozoo.org. However, it is important to note that the California condor is a critically endangered species and is protected by the federal government. The public should not interact with it or inhibit its actions. Human interaction can interfere with its return to San Diego’s wilderness.

On March 24, biologists in Mexico discovered another momentous milestone, the first California condor egg laid in Mexico since their reintroduction.