Sexing Chicks, by Science


I was on the fence about hatching chicks from our flock. I wanted to be able to sell the chicks and I had no idea how to sex them accurately. There are many people who swear by feather sexing, and some who practice enough to become accurate at vent sexing. I don’t have time to learn either of these techniques at the moment, and would have no confidence with my guesses.

But, lo and behold, I was finally persuaded to give hatching our eggs a go when I found out that we had a special combination of chicken breeds that would make everything very easy.

The eggs I wanted to hatch were from Barred Rock hens and a very handsome black Australorp rooster. Based on the chicks’ coloring and basic genetic inheritance, we are able to tell as soon as the chicks hatch if they are male or female.

A delightfully blurry photo of a feeding frenzy. Just to illustrate the coloration of the Barred Rock hens (foreground) and our black Australorp rooster (eating from my husband’s hands).

Here’s the magic:

The barring gene, the one that makes Barred Rocks have their unique black and grey coloring, is a sex-linked characteristic. Now dust off your old genetics books…

A sex-linked gene is a gene that hitches a ride on the sex chromosome instead of the regular chromosomes (humans have 46 chromosomes and only two of these are sex chromosomes). This means that a sex-linked characteristic is much more common, or occurs only in, one sex.

Birds’ sex chromosomes are not the X and Y we are so familiar with, but Z and W. And as you may know, in humans the male is XY and the female is XX. However, birds turn this on its head, as the males are ZZ and the females are ZW.

Now, barring is a sex-linked characteristic that’s attached to the Z sex chromosome. So if we breed an all black rooster to a barred hen…

Chicken Punnet Square

All of the males will have one copy of barring from their mother and one copy of black from their father. This results in a chick that resembles a pure Barred Rock, however when they grow up their barring will be less defined than it would be if they had two copies of the barring gene. Purebred male Barred Rocks, with two copies of barring, have much finer bars of coloring than the purebred females do, with only one copy.

All of the female chicks we hatched would have one copy of black from their father, but they all received the Z chromosome from their mother. So all they have to show is black.

My initial research claimed that we would be able to tell who was female as they would have black heads, whereas the males would have some white on their heads. We found this to be true, however we also found that the females had black beaks and most of their feet were black as well (except the tips of their toes). The males did have more white, especially on their chests and heads, and their beaks and feet were white as well.

With the male on the left and the female on the right, you can see the differences in coloring very easily.

From our first round of incubator we got three males and three females. I expected zero to hatch, so I’m quite pleased we have little chickies¬†running around. I did a few things wrong when I was storing the hatching eggs, so I’m hoping to hatch even more next time. Keep an eye on this page if you’re interested in getting some chicks of your own. We will definitely be hatching more in the future!

After about a week we noticed the females had longer feathers growing in on their wings and tails than the males did. It looked like they were a few days ahead of the boys, even though they all hatched on the same day. By two weeks old we could easily see the barring coloration on the males, while the females were still mostly black.

Males are on the left and females are on the right.

There are other breeds with colorations that are sex-linked, so this is not the only combination of breeds to choose from. This resource is very interesting if you want to know about some other breed combinations and more about feather sexing.

Have you hatched your own chicks? Was any of this information helpful? Comment below!

Author: Kaya

Kaya Diem has been farming on some scale since 2007, from rabbits to radishes and sheep to squash, she hopes to someday be as self-sufficient as possible. Kaya graduated from Oregon State University in 2014 with an Animal Sciences degree. She lives in Seaside, OR with her husband, dog, and various farm critters on about 5 acres.

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