19 March 2013

Finding Out The Reason Why Roosters Crow

Japanese researchers are studying the reasons why roosters crow. They believe that by trying to explain why cocks crow would also help in understanding other animal behavior such as the purring of a cat or the barking of a dog.

For most, a cock's crow symbolizes the breaking of a new dawn. Like an alarm clock, it symbolizes the early morning. Although roosters can crow at any time of the day, it is during daybreak and dusk that they become more active in crowing.

There are many reasons that come up as to why roosters crow. Some of these are:

1. To announce the breaking of a new dawn

2. To show dominance among the other roosters around

3. A muscle reflex after waking up similar to a yawn

Researchers in Japan are studying whether this action is based on environmental factors or is it because of a biological or psychological trigger.

Environment or Circadian Rhythm?

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, a Cell Press publication, 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 external stimuli."

Video: Why Do Roosters Crow?

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

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 circadian clock.

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."


Cell Press
Nagoya University
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