Study: Roosters Crow Based On Internal Clock, Not Sunrise

CAMBRIDGE, Mass. (CBS Connecticut) – Researchers have learned that roosters are genetically programmed as to when to greet the morning with a “Cock-a-doodle-doo!”

The study, published in the journal Current Biology whose offices are located in Cambridge, Mass. as well as abroad, found that roosters know when to crow based on what is called a circadian clock – essentially, an internal clock that helps the birds know what time it is in a given day.

“Although external stimuli such as light and crowing by other individuals also induce roosters’ crowing, the magnitude of this induction is also regulated by a circadian clock,” an abstract summary of the study, published on the Current Biology website, additionally noted.

The study was conducted by researchers at Nagoya University in Japan, the website LiveScience learned.

“‘Cock-a-doodle-doo’ symbolizes the break of dawn in many countries,” study author Takashi Yoshimura was quoted as saying 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.”

In order to get an answer, 40 roosters were reportedly housed in a setting lit consistently to the same degree. Researchers then observed the times at which the roosters sounded off.

Even in the light-controlled room, the roosters were said to have crowed at the break of dawn.


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