News / Science & Technology

Roosters' Dawn Crowing Set by Internal Clock, Not Rising Sun, Study Says

TEXT SIZE - +
VOA News
Japanese researchers say they have proof that an internal biological clock -- the so-called Circadian rhythm -- plays a role in letting roosters know when it's time for their morning crow.

The sound of a rooster's familiar morning greeting -- known to many as "cock-a-doodle-doo!" -- often occurs like clockwork as the rising sun lights up the eastern horizon at the start of a new day.

But how do roosters know when it's time to perform? Do they have an internal sense of the time of day, functioning like nature's alarm clocks, as some experts believe? Or are they just reacting to what's going on around them, prompted to crow by the sunlight or other environmental cues?

"'Cock-a-doodle-doo' symbolizes the break of dawn in many countries," says Takashi Yoshimura of Nagoya University. Writing in the journal Current Biology, Yoshimura added it's not clear whether crowing is under the control of a biological clock or is simply a response to external stimuli.

Yoshimura notes that roosters don't only crow at dawn, but also at other times of the day, which suggests that external factors, such as the stray glare of a car's headlights, or the sound of another rooster crowing nearby, can motivate the bird's vocalizations.

To find out the degree to which internal and external factors prompt the morning crowing, Yoshimura and his colleague Tsuyoshi Shimmura exposed a group of roosters to constant "dawn" light and then turned on their recorders so that they could watch and listen to them.

Kept under this steady simulated twilight, the roosters initially maintained their schedule of crowing just before dawn each morning, suggesting that the behavior is linked to a Circadian rhythm, a natural synchronization many plants and animals -- including humans -- have with the Earth's 24-hour day-night cycle.

The researchers noticed that while the roosters could be spurred to crow throughout the day by external factors, the intensity of their crowing was greatest at the dawn hour.

Over time, however, the daily crowing became more scattered, suggesting that the birds' Circadian rhythm was weakened by their regimen of perpetual twilight.

The researchers believe these behaviors indicate that the roosters' internal Circadian clock not only governs their morning crowing, but also moderates their response to external stimulation.

Yoshimura and Shimmura say that this study is just the beginning of their efforts to learn more about roosters' natural vocalizations, which they say are not learned like most other bird songs or human speech.

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

You May Like

Algerians Vote in Presidential Election

There were few media reports of protests and clashes around the country, but so far no significant violence More

Sharks More Evolved than Previously Thought

The discovery could “profoundly affect our understanding of evolutionary history” More

Pakistan Military Asked to Protect Polio Workers

Request comes as authorities say a Taliban ban on vaccinations in 2012 and deadly attacks on anti-polio teams have prevented thousands of children from getting inoculated More

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Google Buys Drone Companyi
|| 0:00:00
...
 
🔇
X
George Putic
April 15, 2014
In its latest purchase of high-tech companies, Google has acquired a manufacturer of solar-powered drones that can stay in the air almost indefinitely, relaying broadband Internet connection to remote areas. It is seen as yet another step in the U.S. based Web giant’s bid to bring Internet to the whole world. VOA’s George Putic reports.
Video

Video Google Buys Drone Company

In its latest purchase of high-tech companies, Google has acquired a manufacturer of solar-powered drones that can stay in the air almost indefinitely, relaying broadband Internet connection to remote areas. It is seen as yet another step in the U.S. based Web giant’s bid to bring Internet to the whole world. VOA’s George Putic reports.
Video

Video Ray Bonneville Sings the Blues and More on New CD

Singer/songwriter Ray Bonneville has released a new CD called “Easy Gone” with music that reflects his musical and personal journey from French-speaking Canada to his current home in Austin,Texas. The eclectic artist’s fan base extends from Texas to various parts of North America and Europe. VOA’s Greg Flakus reports from Austin.
Video

Video Millions Labor in Pakistan's Informal Economy

The World Bank says that in Pakistan, roughly 70 percent work in the so-called informal sector, a part of the economy that is unregulated and untaxed. VOA's Sharon Behn reports from Islamabad on how the informal sector impact's the Pakistani economy.
Video

Video Passover Celebrates Liberation from Bondage

Jewish people around the world are celebrating Passover, a commemoration of their liberation from slavery in Egypt more than 3,300 years ago. According to scripture, God helped the Jews, led by Moses, escape bondage in Egypt and cross the Red Sea into the desert. Zlatica Hoke reports that the story of the Jewish Exodus resonates with other people trying to escape slave-like conditions.
Video

Video Police Pursue Hate Crime Charges Against Kansas Shooting Suspect

Prosecutors are sifting through the evidence in the wake of Sunday’s shootings in a suburb of Kansas City, Missouri that left three people dead. A suspect in the shootings taken into custody is a white supremacist. As VOA’s Kane Farabaugh reports, he was well-known to law enforcement agencies and human rights groups alike.
Video

Video In Eastern Ukraine, Pro-unity Activists Emerge from Shadows

Amid the pro-Russian uprisings in eastern Ukraine, there is a large body of activists who support Ukrainian unity and reject Russian intervention. Their activities have remained largely underground, but they are preparing to take on their pro-Moscow opponents, as Henry Ridgwell reports from the eastern city of Donetsk.
Video

Video Basket Maker’s Skills Have World Reach

A prestigious craft show in the U.S. capital offers one-of-a-kind creations by more than 120 artists working in a variety of media. As VOA’s Julie Taboh reports from Washington, one artist lucky enough to be selected says sharing her skills with women overseas is just as significant.
Video

Video UN Report Urges Speedier Action to Avoid Climate Disaster

A new United Nations report says the world must switch from fossil fuels to cleaner energy sources to control the effects of climate change. The Intergovernmental Panel on Climate Change released the report (Sunday) following a meeting of scientists and government representatives in Berlin. The comprehensive review follows two recent IPCC reports that detail the certainty of climate change, its impacts and in this most recent report what to do about it. VOA’s Rosanne Skirble has the details.
AppleAndroid