Cock-A-Doodle-Doo! Roosters Really Do Know What Time It Is

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Roosters crow in the mornings because their internal clock tells them to, new research suggests. (Image credit: Current Biology, Shimmura et al.)

The rooster's morning cock-a-doodle-doo is driven by an internal clock, finds new research, suggesting the male chickens really know the time of day.

The study, detailed today (March 18) in the journal Current Biology, found that roosters put under constant light conditions will still crow at the crack of dawn.

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

Because stimuli throughout the day — such as car headlights — will set off a rooster's crow at any time, it was also possible that increasing light was the trigger for the cock's crows.

To find out Yoshimura and his colleagues put 40 roosters in a setting with constant light, then recorded when they crowed.

Sure enough, the chickens crowed at daybreak regardless of the light conditions. The roosters also crowed at other times of day and in response light and the crows of their fellow chickens, but those behaviors were much stronger at daybreak. The findings suggest that an internal circadian clock, rather than external conditions, drive the behavior.

As a follow-up, the team hopes to determine the genetic underpinnings of other animal sounds.

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

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Tia Ghose
Tia Ghose
Editor-in-Chief (Premium)

Tia is the editor-in-chief (premium) and was formerly managing editor and senior writer for Live Science. Her work has appeared in Scientific American, Wired.com, Science News and other outlets. She holds a master's degree in bioengineering from the University of Washington, a graduate certificate in science writing from UC Santa Cruz and a bachelor's degree in mechanical engineering from the University of Texas at Austin. Tia was part of a team at the Milwaukee Journal Sentinel that published the Empty Cradles series on preterm births, which won multiple awards, including the 2012 Casey Medal for Meritorious Journalism.