In the film Chicken Run, the two rats, Nick and Fetcher, make a deal with Rocky for all his eggs, only later learning that they’ve been conned because, “It’s a lady thing, apparently.” But at one point, Nick asks how the egg is coming, and Rocky says, “This is a double yolker.”
That got me thinking. It isn’t that I’m unaware of double and even triple yolk eggs. I really like chickens and I used to care for a clutch of chickens. But my experience with a multiple volk was in the context of a frying pan. Rocky’s comment made me think, “What would happen if the eggs had been fertilized and allowed to hatch?
How Are Twin Chickens Created?
I guess I should point out something that may come as a bit of a surprise to some people. That hard casing that we call an egg is not, in fact, the egg. The egg is the inside.
It is released into the hen’s oviduct. Once there, the shell is created around it. On occasion, a hen will release two (or more) eggs into the oviduct. In that case, the shell will form around the eggs.
Can Twin Chickens Survive?
When I started researching this article, my big question is whether twin chickens survive in nature. As it is, there is very little room inside the shell for even a single chick. On the other hand, double yolk shells are larger than normal shells as you can see in this image.
There are two potential problems that make twin chickens unlikely. And strangely, they are both due to the size of the egg: both because it is too big and because it is too small.
Problem 1: Egg Too Big
Because twin eggs are large, hens occasionally become egg bound. This is more or less what it sounds like: the egg shell gets stuck in the hen’s oviduct. Egg size isn’t the only reason for this, however. It happens to very young hens, obese hens, those with too little calcium or too much protein.
Check the link above if you want more information. Lisa Steele, the woman behind Fresh Eggs Daily, has all the information — and helping a chicken from this fatal problem is actually a lot less complicated than you would think.
Problem 2: Egg Too Small
The second problem that limits the survival of twin chickens is that despite the larger shell, there is too little room for the two chicks. This doesn’t mean that twin chickens are doomed in the wild, however.
According to Steele in private correspondence, “A double-yolked egg can hatch on its own, but rarely do both chicks make it because there’s just not enough room inside the shell for both to develop correctly. But it can happen.”
Why Do Hens Create Twin Eggs
Multiple-yolk eggs are much more common among hens who are just starting their laying careers, and those who are at the end of them.
But in Asia, hens are bred to produce multiple yolk eggs because they are seen as a kind of delicacy. I’m not sure how nice that is to the chickens, but regardless, much worse is done to chickens in this country.
A Live Birth!
My sister pointed me to two videos of hatching twin chickens. They were created six years ago by a woman (Rebecca Bowers?) under the account NeedMoreChickens. Sadly, the channel has been closed. Thankfully, I found the first video again! It shows her carefully hatching a pair of twins. It is amazing, delicate work. And even though it is over ten minutes long, it’s almost impossible to stop watching. Or maybe it is just because I like chickens so much. Here it is:
There was a second video that showed the chicks a few hours later, dry and fluffy, walking around. She then hatched a second set of twins. One of them was dead. It apparently had been for a while, because it hadn’t developed eyes. That’s sad, but according to the video, all three of the ones that survived were doing great. So with the help of caring humans, twin chickens stand a very good chance of surviving birth, which is awesome!
Baby Chicken via Pxhere; it is in the public domain. Egg Comparison by Andrea Black; licensed under CC BY-SA 2.0.
Thanks for posting this. I often wondered if a double yolk egg can produce two chicks . I asked several people and no one could answer me. I have an older hen who lays double yolk eggs all the time. Some of the other chickens are broody and I wondered what would happen if I gave them one of the older hen eggs.
Yeah, the question’s been bothering me for while. Now I have another question: what about identical chicken twins?
A member of my family roasted a chicken a week ago and when they carved the breast, there was a very small, undeveloped chick actually incorporated in the breast meat! Would that have been a conjoined twin?
Wow! I don’t know. I would run in past the chicken expert I mentioned in the article. She seems to know everything!
I would imagine that, in the history of the world, there have been identical twin birds of some sort. Why not? It’s probably very rare, though.
Yeah, the only reason it wouldn’t be is because there is some reason why it couldn’t. And I doubt that’s the case.
To the best of my knowledge identical chickens (being from a single yolk) would be beyond rarer than hens teeth due to the fact the chick absorbs the yolk before it hatches. There are instances of conjoined twins as they both try to absorb the same yolk.
My sources indicate that in the wild, twin chicks would be extremely rare. But not as rare as hens with teeth, unless I’m mistaken about hen mouths.
I’m no expert. I just find it fascinating.
The yolk is the chick. It is the albumen/white that is absorbed as the chick develops.
My understanding is that the chick is actually inside the yolk. It is tiny at first. I’ve always assumed that the yolk provided nutrients to the chick fetus. And the white perhaps provides protection against shocks and other motion.
Feel free to update me. I love chickens, but I’m no expert!
Thanks for the blog. I just boiled a bunch of extra large eggs (they are *really* big) and as I was eating them, realized that about half of them had two yolks. I assumed that meant twin chickens were “a thing” but wanted to find out for sure.