Understanding Sex-Link Hybrid Chickens

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By Don Schrider – At Backyard Poultry we get questions all the time asking for help identifying the breed of various chickens. Many times the chickens pictured are not purebred chickens at all but crossbreeds / hybrid chickens hatcheries produce for very specific purposes – such as egg production. Such poultry can be very productive and useful for the backyard fancier but cannot be considered a breed.

Terminology

Before we go too far in stating what “is” and what “is not” a breed, there are some terms we need to define. First, what does the word “breed” really mean? We can define “breed” as a group of animals with similar characteristics that, when bred together, will produce offspring with the same characteristics. In other words, a breed breeds true. The advantage of pure breeds is that each generation of offspring can be counted on to look and perform in the same way as the previous generation.

Breeds were often developed due to geographic isolation or for specific purposes. For instance, Rhode Island Red chickens were developed in Rhode Island and are brown egg layers. Each generation will be “red” in color and lay brown eggs, just as their parents did—and at much the same rate of production. Purebred Rhode Island Red chickens, when mated to purebred Rhode Island Red roosters, do not produce offspring barred in color or that lay green or white eggs.

Mongrels, crossbreeds, and hybrid chickens are all terms that mean the birds are not pure breeds. Each of these terms has some historic relevance worth knowing in order to help understand how they relate to pure breeds. The idea of purity in a genetic population has old roots, but was not widely applied to poultry until the 1800s. At this time there were only a few “breeds,” most flocks of chickens displayed a variety of color characteristics, sizes, rates of production, etc. Little thought was given to selective breeding. These flocks were referred to as “mongrels” or “mongrel poultry.”

History

At the time (circa 1850), more and more poultry from diverse parts of the globe became available in North America and Europe. Crossing of Asian and European stock formed the basis for many new “improved” breeds—such as American breeds like the Plymouth Rock or the Wyandotte—these “improved” breeds formed the basis for a burgeoning emphasis on poultry farming as a standalone farming enterprise.

The fact that purebred poultry could be relied upon to produce predictable results, generation after generation, and the fact that they were productive, by the standards of that time period, were the basis of profit that could be relied upon. Any chicken that was not a pure breed was referred to as a mongrel and the meaning was derogatory.

Crossing Breeds

A crossbred chicken (today often called the hybrid chicken) is simply the result of crossing two or more purebred chickens. There is nothing new about crossing breeds. I like to think that human curiosity—that desire to wonder, “what would you get”—led to many experiments. All throughout the late 1800s and early 1900s, some poultrymen would cross various pure breeds. This may have started as a curiosity, but a few of these crosses were found to produce faster growth, meatier bodies, or higher egg production.

During the early 1900s, poultrymen supplying chickens for meat found these crosses advantageous, but popular opinion had already been formed against chickens that were not purebred. Early promoters of these crossbred chickens knew they needed a new term for their poultry to disassociate them from the derogatory connotations of terms like “mongrel” or “crossbreed.” As they noticed some improvement in rate of maturity and growth, they stole a term from plant breeding—the term “hybrid.” And thus hybrid chickens became acceptable nomenclature.

Hybrid chickens could be relied upon to grow slightly faster and lay well. They also exhibited that same trait we find when we cross two breeds of almost any animal – vigor, a.k.a. hybrid vigor. Vigor and faster rates of growth in hybrid chickens were true advantages in meat production and eventually led to the birth of today’s 4-way cross industrial meat chickens. But for many decades the need to keep and produce breeding stock for two or more pure breeds in order to have stock to produce the hybrid chickens was of no advantage to the farmer/ poultryman; cost simply outweighed any advantage. Pure breeds were still the preference for the production of eggs.

Meat Production and Sex-links

Back to meat production for a moment: Probably the most famous cross to produce fast growth and meaty chickens for market was the cross of the Cornish breed to the Plymouth Rock breed. These hybrid chicken became known as CornRocks or Cornish crosses. CornRock pullets, however, were not very good layers and did have large appetites. But other crosses were also very important. For many years New Hampshire Reds were crossed with Barred Plymouth Rocks – producing fast-growing, meaty and tasty market poultry. From this cross, a few white spots were produced—and thus the Indian River or Delaware breed was born. Poultrymen noticed that these various crosses of breeds with different colors did produce pullets that laid very well. They also noticed something interesting—the chicks from these crosses often had easily noticed differences in down color, which made it easy to learn how to tell the sex of baby chicks for these crossbreeds. In other words, the color of the male and female offspring from these crosses were linked to the sex of the chick. And so the “sex-link” chicken was born.

Anyone that has wanted to purchase only female chicks to grow out for raising chickens for eggs can easily see the advantage of having chicks with down color being linked to sex—anyone can distinguish the males from the females at hatch. But the disadvantage comes in that flocks of each of the two parent breeds must be maintained in order to have birds with which to make the cross to produce the sex-link chicks. Sex-link crossbred/hybrid chickens can be mated and will produce offspring, but color, rate of growth, and egg laying ability will vary much from one offspring to another. This means that for those that wish to produce their own stock, sex-link chickens offer no advantage.

Are They a Breed?

Because sex-link chickens do not produce offspring that look and produce as well as they themselves do, they are not breeds. They simply do not fit the definition of a breed. So what are they? Since they are the result of crossing two (or more) breeds, they may only be termed crossbreeds.

So if you have a sex-link chicken and you wonder what breed it is—it is not a breed but a crossbreed.

Poultry Color 101

Before we talk about the various types of sex-links available, let us talk a little about poultry color genetics. In poultry, the males carry two full genes for color and the females carry the sex-determining gene and one gene for color. This is true in all avians and is the opposite of what we see in mammals (and people).

Different color genes are dominant or modify other color genes, for example; the barred color is the result of genes for black plus a gene for barring. Since the males have two genes for barring and the females only one, we can see that in barred breeds the males have finer barring than the females. When we breed a barred hen to a solid color male, her daughters do not receive the barring gene but her sons do get one dose of barring. As day-old chicks, males carrying a barring gene will have white on their heads while their sisters without will be solid black.

Breeds with white color or some white color often carry what we call the silver gene. This is a dominant or partially dominant gene—meaning it only takes one dose to express itself. When a female with the silver gene is crossed to a solid colored male, her sons will be white and her daughters will be the color of their father (though often with white undercolor). Male chicks will hatch with yellow down and females will be like their dad (usually buff or red tinted).

When we breed a barred male to solid color females, his daughters get a normal and full dose of barring and his sons get only one gene, or half the normal dose, of barring. If the hen used was black, all the chicks will be barred. If the hen carries the silver gene, then the daughters will be barred and the sons white or white with barring. As chicks, we would see yellow down on males and black down with white spots on females.

The Sex-links

So what are the various types, or kinds, of sex-link chickens? We can divide these as either red sex-links or black sex-links. Popular names under which they are marketed include: Cherry Eggers, Cinnamon Queens, Golden Buff and Golden Comets, Gold Sex-links, Red Sex-links, Red Stars, Shaver Brown, Babcock Brown, Bovans Brown, Dekalb Brown, Hisex Brown, Black Sex-links, Black Stars, Shaver Black, Bovans Black and California Whites.

Common Black Sex-link Crosses

Black sex-links are the result of crossing a Rhode Island Red or New Hampshire Red rooster over Barred Plymouth Rock females. Both sexes hatch out black, but the males have a white dot on their heads. Pullets feather out black with some red in neck feathers. Males feather out with the Barred Rock pattern along with a few red feathers. Black Sex-links are often referred to as Rock Reds.

Common Red Sex-link Crosses

Red sex-links are the result of crossing a Rhode Island Red or New Hampshire Red male over White Plymouth Rock, Rhode Island White, Silver Laced Wyandotte, or Delaware females.

Specific crosses: a New Hampshire male is crossed with White Rocks with the silver factor to produce the Golden Comet. New Hampshire males crossed with Silver Laced Wyandottes gives the Cinnamon Queen. Two other crosses are obtained with Rhode Island Red x Rhode Island White, and Production Red x Delaware. These two crosses are simply called Red Sex-links.

Generally, red sex-link males hatch out white and, depending on the cross, feather out to pure white or with some red or black feathering. Females hatch out buff or red also depending on cross, and they feather out in one of three ways: buff with white or tinted undercolor (such as Golden Comet, Rhode Island Red x Rhode Island White); red with white or tinted undercolor (Cinnamon Queen); red with red undercolor (Production Red x Delaware).

Other Sex-link Crosses

Bovans Goldline chickens are a European sex-link produced by crossing Rhode Island Red males with Light Sussex. This cross produces red hens and roosters largely white in color.

ISA Browns are another sex-link cross from stocks owned by the multinational poultry corporation ISA—Institut de Selection Animale. It is produced by crossing a Rhode Island Red type male with a commercial White Leghorn female.

The California Gray was developed around 1943 by famous poultryman Horace Dryden from his family’s lines of production White Leghorns and Barred Plymouth Rocks. He wanted a breed of fowl that would dress out at four pounds—a little larger than a Leghorn— but lay white eggs.

California Whites are the result of crossing a California Gray rooster to a White Leghorn hen. The sire carries the barring gene, and gives one barred gene to sons and one to daughters. The dam carries the dominant white gene and gives this only to sons. So, in theory, the sons are white and the daughters are white with black mottling or barred in color. As chicks, the sons’ down color should be clear yellow on the tops of their heads, the daughters should have black spots on their heads. (Both may have some black spots on bodies, but the males fewer and smaller spots.)

Conclusion

While you may have a nice flock of sex-link chickens, producing many wonderful eggs, a breed they are not. You can refer to these hybrid chickens as a “kind” or a “type” of chicken and be correct. But they will not breed true and that is the basic meaning of a breed. So be proud of your hens and enjoy the fruits of your labor!

Don Schrider is a nationally recognized poultry breeder and expert. He has written for publications such as Backyard Poultry, Countryside and Small Stock Journal, MOTHER EARTH NEWS, Poultry Press, and the newsletter and poultry resources of The  Livestock  Conservancy.

He is also the author of a revised edition of Storey’s Guide to Raising Turkeys.

Text © Don Schrider, 2013. All rights reserved.

Originally published in 2013 regularly vetted for accuracy.