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Science & the Public

Lost to history: The “churk”

Chickens and turkeys weren't meant to cross

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More than a half-century ago, researchers at the Beltsville Agricultural Research Center outside Washington, D.C., engaged in some creative barnyard breeding. Their goal was the development of fatherless turkeys — virgin hens that would reproduce via parthenogenesis. Along the way, and ostensibly quite by accident, an interim stage of this work resulted in a rooster-fathered hybrid that the scientists termed a churk.

The creatures were literally twisted, with crooked legs and beaks and feathers exhibiting a strange torsion.

Adding insult to injury, the crosses were mentally retarded, possessing only about half of the intelligence of their parents, according to Marlow Olsen, who headed the fowl research project.

It would be tempting to call this bird an ugly chuckling or pathetic gobbler — except that the hybrid remained largely silent unless disturbed. Then it emitted a puny chickeny chirp.

But that didn’t prevent Science News from crowing about the animal as a “history making cross” in its November 5, 1960, cover story. The story billed it as "the first known hybrid of two families of birds."

The text also suggested why we’d hear little more of the animal. The hybrids were all male, so they couldn’t reproduce — except, I guess, by cloning (which wasn’t an option at the time). The offspring proved devilishly difficult to nurture, even just to hatching. The three Beltsville birds that lived to seven months of age were the sole survivors of 2,900 artificially-inseminated eggs.

Olsen was not the first to encounter trouble creating a chicken-turkey hybrid. A 1960 paper he authored in the Journal of Heredity cited a reference to 12 trials, none of which resulted in a single hatchling. Several additional reports claimed to produce a few live young, he says, but offered no details. Part of the problem likely traced to a dramatic mismatch in the parents’ genomes.

Chickens possess six pairs of chromosomes, turkeys have nine. Each offspring receives one-half of each pair from its mom and dad, which are supposed to then create new matched pairs. Except that the 15 chromosomes that each hybrid started with had no chance of pairing appropriately.

Mother Nature, however, has created what looks like a healthy chicken-turkey hybrid: the colorfully named Transylvanian Naked Neck bird. There are no turkeys in this animal’s ancestry, however. Once dubbed a Churkey or a Turken because of its hybrid appearance, this chicken developed its distinctive look from a complex genetic mutation.

And as their name implies, these chickens have featherless necks.

”We initially worked on identifying the mutation that causes the naked neck trait in chickens as we are interested in understanding how patterns arise during development,” explains Denis Headon of The Roslin Institute and University of Edinburgh’s Royal School of Veterinary Studies in Scotland. He says his team traced the trait to where “part of chromosome 1 had moved across to chromosome 3 and inserted there.” Followup studies, he adds, showed that the neck skin of birds “is generally primed to allow loss of feathering. His team described some of their findings, earlier this year, in PLoS Biology.

As for Transylvania as the birds’ ancestral home: “This seems quite unlikely,” Headon says. “Domestic animals often have geographically misleading names (the turkey itself being a great example).” Naked necked chickens occur around the world. In some parts of the Middle East, Africa and Asia, he ventures, “this may be partly because they are more tolerant of heat than are fully feathered chickens.”

Citations

M.W. Olsen. Turkey-chicken hybrids. Journal of Heredity, Vol. 51, March 1960, p. 69.

K. Harada and E. G. Buss. Turkey-chicken hybrids: a cytological study of early development. Journal of Heredity, Vol. 72, July 1981, p. 264. Abstract: [Go to]

C. Mou, . . . and D.Headon. Cryptic patterning of avian skin confers a developmental facility for loss of neck feathering. PLoS Biology, Vol. 9, March 15, 2011, p. e1001028. doi:10.1371/journal.pbio.1001028

Further Reading

History-Making "Churk", Science News Letter, Vol. 78, November 5, 1960, p. 291. Available to subscribers: [Go to]

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