As every backyard chicken breeder knows, the biggest challenge with raising chickens is that you often end up with far more roosters than you need. It takes only a single rooster to cover a flock of twenty hens, yet fully half of all the chicks that hatch are males.  If the inconvenient surplus of male chickens is vexing to you, the backyard hobbyist, imagine its impact on a quickly industrializing world in the early 20th Century as nations clamored for more food and desperately sought to wring every efficiency from their farms, coops, and fields.

Although chickens have been domesticated for perhaps as long as 8,000 years, until recently it was impossible to easily distinguish male chicks from females until the birds were at least a month old.  Over the centuries myth and legend had grown around the subject of chick sexing.  It was believed, for example, that a long narrow egg held a male chick and a short round egg housed a female chick.  These tales offered little help to farmers intent on making a living.

A century ago, farmers could ill-afford to waste animal feed and labor growing unidentifiable and ultimately unmarketable male chicks. The problem was compounded with the development of the first large commercial electric incubators in the 1920s, and this new ability to reliably hatch millions of chicks carried with it the urgent necessity to sex chicks as soon as they hatched.

In the early 1920s a number of strategies were pursued around the globe to solve the difficult problem of sexing day-old chicks. The Japanese were the first to master vent sexing; a rapid examination of the internal sex organs of the chick. But, the British pursued an entirely different strategy championed by a restless genius, Dr. Reginald Punnett, a professor at Cambridge who essentially founded the study of genetics at that esteemed university.

Punnett hypothesized that the gene for barred color patterns acted differently in male and female chicks. The males received two barred genes and the females only one, so male chicks would be lighter in color and more barred than the females. He experimented and found that by crossing brown colored males with barred silver females (he favored the Plymouth Rock to supply the barring gene), the effect was accentuated, and chicks could be easily visually sexed by their color and down patterns on the day they hatched. Females tended to have clearly defined “chipmunk stripes” on their backs and males tended to have a silver sheen on their down with a light spot on the backs of their heads.

As his first “proof of concept” experiment, Punnett was able to cross a Campine rooster with a barred Plymouth Rock hen and produce a chick that was visually sexable immediately after hatching. Male chicks had the telltale white spot behind their heads and female chicks had well-defined stripes in the down on their backs. These powerful visual cues for the first time in history made sexing chicks a simple task. Punnett’s new creation, dubbed the Cambar, was shown for the first time at the 1930 World’s Poultry Congress at the Crystal Palace in London. The Cambar was the first intentionally created auto-sexing breed of chicken. It was nothing less than revolutionary.

After the Cambar proved Punnett’s theory about auto-sexing –the Cambar was a poor commercial bird and later became extinct– the professor departed on a more intricate path. The second breed produced by Punnett, and the one that reveals his quirky wit, was primarily a combination of three breeds: A high-producing Danish strain of brown Leghorn (for its legendary egg laying ability), the barred Plymouth Rock, and the exotic Araucana (for its blue egg laying ability and its jaunty feather crest) that by the late 1920s had made its way to Britain from the remote regions of Chile.  At some point in the creation of the Legbar Punnett also blended in genetics from other breeds like Hamburgs, Rhode Island Reds, and white Leghorns.  Punnett’s work yielded a shocking mix of the practical and the whimsical; an auto-sexing breed with flamboyant feathers that cranked out an enormous volume of sky-blue eggs. While Punnett would later go on to create more than a dozen auto-sexing breeds, it is this breed –the Legbar– that today is the most popular auto-sexing chicken breed in the world and still enjoys a place in the commercial flocks of Britain.

In 1929, Punnett and his colleagues began the initial breeding experiments that were to yield the Legbar, a breed that Punnett created in both a gold and cream variety. It took almost two decades to produce a bird that was genetically stable and exhibited the odd array of traits first envisioned by Punnett.   Although the Cream Legbar is the best known example of auto-sexing chickens, the auto-sexing class now spans a number of breeds that were developed in the UK: the Rhodebar, Wybar, Barnebar, Brussbar, and Welbar, among others.

Auto-sexing breeds also began to emerge in other countries. For example, the Bielefelder is an auto-sexing breed developed in Germany in the 1970s.  The Niederrheiner is an Austrian auto-sexer, and in the 1950s Father Martin Silverudd in Sweden developed a number of auto-sexing breeds that lay eggs in a variety of colors.  All told there are probably more than two dozen auto-sexing chicken breeds that emerged in the 20th Century, although some breeds had but a brief moment on the agricultural stage and later drifted into extinction.  And, auto-sexing chickens produced a rainbow of egg colors:  blue (Legbar), white (Fifty Five  Flowery Hen), dark brown (Welbar), tan (Rhodebar), cream (Niederrheiner), and green (Isbar, although their auto-sexing function is iffy).

Curiously, Americans showed little interest in auto-sexing breeds and ultimately chose a different path. In the United States, it is common to buy visually sexable day-old chicks that are sex-linked –as opposed to auto-sexing—chicks. It’s helpful to grasp the distinction between auto-sexing chicken breeds and sex-linked chickens. Both create a visually sexable chick, but there are major differences between the two approaches that have powerful implications for the backyard poultry hobbyist.

Traditionally, the American poultry industry has relied on the sex-linked function to create visually sexable chicks. If you go to your local feed store and want to buy visually sexable chicks in the spring, you are buying sex-linked –as opposed to auto-sexing– chicks. Sex-linked chicks are the first generation hybrids of two separate chicken breeds. They are produced by the hundreds of millions each year in large commercial hatcheries. If you allow the sex-linked chicks to reach adulthood and breed with one another they will not produce visually sexable chicks in the second generation. In other words, until recently if you wanted to buy visually sexable chicks in America, you’d be traveling to that feed store year after year to buy sex-linked birds produced by large commercial hatcheries. Your flock of sex-linked birds will not be a self-sustaining flock that can produce visually sexable chicks.

By contrast, auto-sexing chicken breeds produce visually sexable chicks generation after generation, and almost 100% of the chicks are visually sexable. For example, you can buy a pair of Bielefelders now, continue to breed their offspring with each other, and eventually your grandchildren can one day be breeding their progeny and still be producing 100% visually sexable chicks. In this sense auto-sexing chicks are like heirloom vegetables. They have a stable genome that always breeds true, and by saving a little seed stock with each generation you are ready to begin anew each year.

Auto-sexing breeds can help the small-scale chicken breeder to create a self-sustaining, visually sexable flock. This recent arrival in America of the genetics that support auto-sexing is nothing less than revolutionary for hobbyists and farmers who wish to build small-scale poultry operations. By making the choice to be a steward of auto-sexing chickens, you can play an important role in securing your food sovereignty and curating these remarkable chicken breeds.  Greenfire Farms is proud to have introduced a number of auto-sexing breeds to America including the cream Legbar, Rhodebar, Bielefelder, Fifty Five Flowery Hen, and Niederrheiner.

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