The two condors were seen by a biologist Monday. The birds were displaying nesting behavior in a cavity in a large coastal redwood tree in Big Sur, the Salinas, Calif.-based, Ventana Wildlife Society announced.
"For the past 10 years when this sort of thing came up, it turned out to be just in my dreams,'' Kelly Sorenson, the group's executive director, told the San Jose (Calif.) Mercury News. "Now it is a reality.''
He said the last known condor egg in Northern California was collected in 1905.
Sorenson said the location of the nest is kept secret to make sure no one disturbs the birds.
Cousins of the turkey vulture, thousands of California condors once flew from British Columbia to Mexico, the Mercury News reported. The population dwindled to 27 birds during the 1980s.
Biologists captured all remaining wild condors in 1987 and began breeding them in zoos, the newspaper said.