Putting the clock in 'cock-a-doodle-doo'

Mar 18, 2013
Credit: Current Biology, Shimmura et al.

Of course, roosters crow with the dawn. But are they simply reacting to the environment, or do they really know what time of day it is? Researchers reporting on March 18 in Current Biology have evidence that puts the clock in "cock-a-doodle-doo" (or "ko-ke-kok-koh," as they say in the research team's native Japan).

"'Cock-a-doodle-doo' symbolizes the break of dawn in many countries," says Takashi Yoshimura of Nagoya University. "But it wasn't clear whether crowing is under the control of a biological clock or is simply a response to ."

That's because other things—a car's , for instance—will set a rooster off, too, at any time of day. To find out whether the roosters' crowing is driven by an , Yoshimura and his colleague Tsuyoshi Shimmura placed birds under constant light conditions and turned on recorders to listen and watch.

Credit: Current Biology, Shimmura et al.

Under round-the-clock dim lighting, the roosters kept right on crowing each morning just before dawn, proof that the behavior is entrained to a circadian rhythm. The roosters' reactions to external events also varied over the course of the day.

In other words, predawn crowing and the crowing that roosters do in response to other cues both depend on a .

Credit: Current Biology, Shimmura et al.

The findings are just the start of the team's efforts to unravel the roosters' innate vocalizations, which aren't learned like songbird songs or human speech, the researchers say.

"We still do not know why a dog says 'bow-wow' and a cat says 'meow,' Yoshimura says. "We are interested in the mechanism of this genetically controlled behavior and believe that chickens provide an excellent model."

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More information: Current Biology, Shimmura et al.: "Circadian clock determines the timing of rooster crowing." dx.doi.org/10.1016/j.cub.2013.02.015

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ForFreeMinds
1 / 5 (4) Mar 19, 2013
I'm glad Japan is paying for this interesting research. I don't see that it has any practical benefit other than addressing curiosity as to when the rooster crows.