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 of 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?
I guess I should point out something that may come as a bit of a surprise to many people. That white thing we call an egg is not, in fact, an egg. The egg is the inside. It is released into the chicken’s oviduct. Once there, the shell is created around it. Well, on occasion, a chicken will release two (or more) eggs into the oviduct and they will end up inside a single shell. These would be fraternal, not identical, twins. I’m not sure identical twins would be possible with chickens.
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. Check out this picture of one double and two single yolk eggs from Fresh Eggs Daily:
Not surprisingly, 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. 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.
Anyway, getting back to those multiple yolk egg shells, they 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.
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, these are the only two videos she’s ever posted. The first video 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:
The second video, Chapter 2, shows the chicks a few hours later, dry and fluffy, walking around. She then hatches 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 at least with the help of caring humans, twin chickens can survive birth, which is awesome!
The main picture above is cropped to HDTV size from Fresh Eggs Daily, which is a fantastic site for all things chicken. If this article made you more interested in chickens, you should go over there and learn from someone who really knows what she’s talking about.
In a private email, Lisa Steele said that “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.” So we have our answer. But it is clearly best if you have your very own shell!