Hallelujah! Virgin births in birds

Love Jesus? Then you’ll love these virgin-birthed condors, too!

Happy Holidays, everyone! The year is coming to an end and many of us are gearing up for a festive season filled with great food, merriment and good company! If you are religious, you may know the story of Jesus, who was born from the then-Virgin Mary (who knows if she stayed a virgin throughout her adult life though)!

Today, I have something just as cool as the story of Jesus - the story of California Condors! The act of ‘virgin births’ have been recorded in this critically endangered bird species not just once, but in at least two separate occasions!

Image credit: Undark Magazine. A California Condor spreads its wings.

About 60 years ago, their numbers began crashing. The California Condor, like vultures, is a scavenger bird that mostly feeds on carrion - the decaying flesh of dead animals. Hunting is a big thing in the United States, and guns are armed with lead bullets. Lead poisoning was the leading cause for their decline: Condors were accidentally ingesting fragments of lead-based ammunition as they scavenged on carcasses of hunted animals.

Thankfully, the US government stepped in before it was too late for these birds, and a captive-breeding programme for the California Condor began.

By 1987, all remaining wild individuals were captured and put in zoos. There were only 27 individual birds, though, so it wasn’t like… a massively difficult thing to do…

These surviving birds were bred at the San Diego Wild Animal Park and the Los Angeles Zoo. Numbers rose through captive breeding, and beginning in 1991, condors were reintroduced into the wild. Since then, their population has grown, but the California Condor remains one of the world's rarest bird species. As of December 2020, there were 504 California condors living wild or in captivity.

Image credit: Aeon. Baby California Condors are fed through a ‘puppet mother’. Zookeepers hope to one day release any chicks born under their care into the wild, so raising them around humans, as other captive-bred animals are often raised, was out of the question. Like many birds, condor chicks imprint powerfully on their early caretakers, and no one wanted them to bond with humans.

So, any California Condor birth is a miracle in and of itself, but a virgin birth? A double miracle!!!

A Jesus-worthy miracle: virgin births in critically endangered birds

In 2021, US wildlife researchers were absolutely blown-away when they discovered that two California Condors gave birth without any male genetic DNA.

This act is colloquially called virgin birth, but in the world of science, it’s called parthenogenesis or asexual reproduction.

In reality, though, the two California Condors that gave birth to chicks asexually were not technically virgins - they had previously hatched other chicks in the traditional way. But also, birds don’t really actually have sex the way humans do (with, you know, a stick and a hole) anyway so can they really actually be considered virgins or not virgins, right?

But anyway, back to the California Condor: the discovery was made in two female California Condors that were kept in captivity in the San Diego Wild Animal Park.

Asexual reproduction in animals

The fact that condors are capable of virgin births - formally called parthenogenesis or asexual reproduction - surprised scientists. Parthenogenesis is definitely an extremely rare event among animals, but it has been recorded in other species before. It happens when a cell in a female behaves like a sperm and fuses with an egg.

Among plants and fungi, asexual reproduction is really nothing new.

Among smaller animals, mostly invertebrates, it’s also quite common: it’s been recorded in water fleas, rotifers, aphids, stick insects, some ants, bees and parasitic wasps and more.

Image credit: Business Insider. ‘Thelma’ the Reticulated Python, who lives at Louisville Zoo in Kentucky, had 6 babies in 2012 without ever coming in contact with a male python.

However, among vertebrates (the scientific word for ‘animals with a spine’), it is incredibly rare! The group of vertebrates include mammals such as us humans, birds, reptiles, amphibians, and fishes. Asexual reproduction has only been described in less than 0.1% of vertebrate species!!

The California Condor is part of that magical 0.1%.

Image credit: Audobon Field Guide

Why does asexual reproduction happen, and what are the pros and cons?

The answer to the first question is simple: like the very first Jurassic Park movie says, “Life finds a way.”

Asexual reproduction is a breeding hack that leads to a rapid and significant increase in the numbers of individuals, with little to no commitment to a mate needed. For plants such as weeds, this is great - weeds tends to reproduce asexually, and that’s probably why they seem to spring up out of nowhere and engulf entire lawns in mere weeks.

In animals (both vertebrates and invertebrates), asexual reproduction allows the animals to pass on their genes when times are especially rough, and when males aren’t present.

However, in terms of the pros and cons, it’s a little more complicated. The pros, are, obviously, that the species can go on living even when times are tough, like when the majority of males of the species have been wiped out. Another benefit is that the same genes get passed down from mother to child.

Since there’s no male bird involved, the offspring produced will share the characteristic of their parent identically - you can think of it as a genetic clone.

But, therein lies the problem! The disadvantage of asexual reproduction is that the offspring will be genetically identical to the parent. If the parent falls ill to a certain disease, chances are the child will be extremely susceptible to it, too.

If a colony of animals is made up of too many clones, with little to no genetic diversity, one single bad flu season can wipe out the whole group. Thus, genetically uniform populations are extremely at-risk.

A fun fact: one single variety of banana, called the Cavendish, currently monopolises the banana crop industry. Cavendish is produced as a result of asexual reproduction, not from seeds!

So, banana plantations are extremely susceptible to disease. The previous banana crop monopoly, called the Gros Michel, was, until the 1950s, the single most popular banana plant. That is, until it was ravaged by disease!! Many people believe it is only a matter of time before the Cavendish crop suffers a similar fate - Cavendish plantations are too genetically uniform.

Back to the California Condor!

As mentioned earlier, before we got sidetracked by bananas, asexual reproduction has only been described in less than 0.1% of vertebrate species. And it normally occurs in animal populations that have few or no breeding males (which is why females have to resort to asexual reproduction in the first place).

And that’s why the scientists studying the California Condors were so blown away: the two female Condors that reproduced asexually had been kept in enclosures with other males who were available for breeding!!

In 2021, researchers had been conducting routine genetic screenings of captive California Condors. They discovered that two chicks that hatched decades ago - in 2001 and 2009 - were genetic clones of their mothers and had not inherited DNA from any father bird.

The scientists were not looking for evidence of asexual reproduction; instead, they were doing normal genetic studies we do to track condor parentage when they discovered this miracle.

Plus, both mother condors previously had chicks that were bred in the traditional way.

Image credit: KALW. The goal of the California Condor Recovery Plan is to establish two geographically distinct self-sustaining populations, each with 150 birds in the wild and at least 15 breeding pairs, with a third population of condors retained in captivity.

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

Unfortunately, both of the virgin birthed-chicks have since died quite prematurely. The species can live for over 60 years, but one chick died at age two in 2003, and the other in 2017 when it was seven years old.

For the miracle that asexual reproduction is, I guess it’s not that great if the chicks died that young.

But hey, human males have life expectancies of like, 80 years, and Jesus died in his 30s, so I guess there’s that parallel for virgin births!

Hallelujah!