'Cock-a-Doodle-Doo' in Roosters Controlled by Internal Clock: Study

How do roosters know that they have to crow at dawn? Researchers believe that the internal clock in roosters is the reason behind them going "cock-a-doodle-doo" every morning.

The study was conducted by researchers from Nagoya University, Japan, who have found that genes control the crowing of roosters and that the sounds aren't the roosters' way of responding to environmental signals. Roosters don't just crow only at dawn, sometimes, even strong light can get them crowing at other times of the day. What sets off this crowing was a mystery until now.

"'Cock-a-doodle-doo' symbolizes the break of dawn in many countries. But it wasn't clear whether crowing is under the control of a biological clock or is simply a response to external stimuli," said Takashi Yoshimura of Nagoya University, in a news release. In Japan, the crowing of roosters is " ko-ke-kok-koh" while in German it is "ki-ke-ri-ki".

For the study, researchers kept roosters in a dim-lit room. They found that roosters began crowing just before dawn every day.

Researchers say that roosters crowing before dawn and crowing in response to external stimuli is controlled by a biological clock.

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

The study is published in the journal Current Biology.