California condors: virgin births discovered in endangered birds

US wildlife researchers found that two California condors, a critically endangered bird, gave birth without any male genetic DNA.

The discovery that condors are capable of virgin births – formally called parthenogenesis or asexual reproduction – surprised scientists.

Virgin births have been recorded in other bird species, as well as lizards, snakes, sharks, rays and other fish.

Only about 500 California condors remain in the southwestern United States and Mexico.

In the 1980s, fewer than two dozen birds remained in the wild, but conservation efforts have increased their numbers in recent years.

The peer-reviewed results from the San Diego Zoo Wildlife Alliance were published this week in Journal of Heredity of the American Genetic Association.

The researchers describe how routine genetic screening of captive birds led to the discovery that two male chicks born in 2001 and 2009 were related to their mothers and had not inherited DNA from any parent birds.

All 467 male condors in the breeding pool were tested. What makes the case even rarer is that it is the first time a bird species has had a virgin birth when males were present for breeding.

Parthenogenesis is an extremely rare event, but it has already been recorded in other species. It happens when a cell in a female acts like a sperm and fuses with an egg. It normally occurs in animal populations that have few or no breeding males.

“This is truly an amazing discovery,” Oliver Ryder, study co-author and director of conservation genetics at the San Diego Zoo Wildlife Alliance, said in a statement.

“We weren’t exactly looking for evidence of parthenogenesis, it just hit us in the face. We only confirmed it because of the normal genetic studies we do to prove kinship.”

Unfortunately, both chicks have died since then: one at the age of two in 2003 and the other in 2017 when she was seven.

Both condor mothers previously had chicks raised in the traditional way.

One had 11 chicks, while the other, who had been mated with a male for 20 years, had 23 chicks. She reproduced two more times after the virgin birth.