Some virgin California condors are laying eggs — without help from males

Written by Danielle Chiriguayo, produced by Sarah Sweeney

California condors are getting more attention because it turns out that some of the females’ eggs can fertilize themselves — no male condors needed. The virgin birth phenomenon has been documented in other birds such as chicken and turkeys, and other creatures such as fish and reptiles. 

The phenomenon is called parthenogenesis, says Dr. Oliver Ryder. He’s the co-author of a new study on virgin condor births and the director of conservation genetics at the San Diego Zoo Wildlife Alliance. 

Typically, this type of behavior is seen when certain species don’t have access to a male plant or animal. Ryder says it’s still unclear why this behavior is taking place, but it will certainly be studied. 

“They would lay an egg and very occasionally, in several species, these eggs started to develop and then failed, or in very rare cases, a chick would be produced. And the ability to answer that question in detail about how it happened involves establishing very precise information about the genomes, the chromosomal makeup, the actual DNA sequence of the genome of contours,” Ryder tells KCRW. “And we're in the process of doing that now, but that hasn't been done for any other species of birds. And this is really the first case in which parthenogenesis in birds has been documented using genetic testing.”

He adds that the parthenogenesis might also be a result of small populations, but there isn’t enough evidence to make a decision.

Both chicks have since died, since the study was a retroactive study of parthenogenetic births, but Ryder says researchers are keeping their eyes peeled for more hatches. 

“We are keeping our eyes open to see if there are going to be any more because our monitoring of the California condor population, including [the] determination of the sex of chicks and determination of parentage, is ongoing,” Ryder says. 



  • Dr. Oliver Ryder - director of conservation genetics at the San Diego Zoo Wildlife Alliance