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Transylvanian naked neck chickens.

Transylvanian naked neck chickens' vampire-friendly look is in the genes, a new study says.

Photograph courtesy University of Edinburgh

Christine Dell'Amore

National Geographic News

Published March 15, 2011

Scientists have cracked why the Transylvanian naked neck chicken has a featherless neck—and it isn't to give vampires easier access.

The Transylvanian bird's naked neck results from a random genetic mutation that causes the overproduction of a feather-blocking molecule called BMP12, a new DNA study shows. (Get the basics on genetics.)

The mutation first arose in domestic chickens in northern Romania hundreds of years ago. The naked neck chicken—also dubbed the churkey or turken—has a chicken-like body but a turkey-like head atop a long, deep-red neck.

Surprisingly, when scientists treated standard-breed chicken embryos with BMP12 in the lab, the young chickens developed no feathers on their necks—suggesting the neck is more sensitive to the molecule, according to study leader Denis Headon, a developmental biologist at the University of Edinburgh's Roslin Institute.

To find out why, Headon and his team did a further analysis, which revealed an acid derived from Vitamin A is produced on the chicken's neck skin. The acid essentially enhances the BMP molecule's effects, making the birds' necks bare, they found.

(See "Half-Male, Half-Female Chicken Mystery Solved.")

Naked-Necked Birds Can Handle the Heat

Unlike most genetic mutations, which are generally bad for an animal, the naked-neck tweak has increased naked necks' popularity worldwide.

That's because bare-necked birds are more resistant to heat and thus produce better meat and eggs—especially crucial for poultry producers in hot climates such as Mexico's, Headon said.

And naked necks aren't alone: "We think all birds have this priming or readiness to lose neck feathers first," he noted.

"Once you have a mutation that increases BMP12 in skin, the neck is the region that's ready to lose its feathers—it's already more sensitive."

In the wild, for instance, it's likely that ostriches and storks have lost their neck feathers to stay cool, though it's unclear whether BMP12 played any role. (See National Geographic's collection of bird pictures.)

"Evolution has always found it easy to lose neck feathers whenever it gets hot and the bird gets big."

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