News / Science & Technology

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

    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

    UN Observes International Day of Peacekeepers

    The U.N. honors 3,400 peacekeepers killed since first mission in 1948

    Video Rolling Thunder Tribute to US Military Turns into a Trump Rally

    Half-million motorcycles are expected to rumble Sunday afternoon from Pentagon to Vietnam War Memorial for rally in event group calls Ride for Freedom

    The Struggle With Painkillers: Treating Pain Without Feeding Addiction

    'Wonder drug' pain medications have turned out to be major problem: not only do they run high risk of addicting the user, but they can actually make patients' chronic pain worse, US CDC says

    Featured Videos

    Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
    Chinese-Americans Heart Trump, Bucking National Trendi
    X
    May 27, 2016 5:57 AM
    A new study conducted by three Asian-American organizations shows there are three times as many Democrats as there are Republicans among Asian-American voters, and they favor Hillary Clinton over Donald Trump. But one group, called Chinese-Americans For Trump, is going against the tide and strongly supports the business tycoon. VOA’s Elizabeth Lee caught up with them at a Trump rally and reports from Anaheim, California.
    Video

    Video Chinese-Americans Heart Trump, Bucking National Trend

    A new study conducted by three Asian-American organizations shows there are three times as many Democrats as there are Republicans among Asian-American voters, and they favor Hillary Clinton over Donald Trump. But one group, called Chinese-Americans For Trump, is going against the tide and strongly supports the business tycoon. VOA’s Elizabeth Lee caught up with them at a Trump rally and reports from Anaheim, California.
    Video

    Video Reactions to Trump's Success Polarized Abroad

    What seemed impossible less than a year ago is now almost a certainty. New York real estate mogul Donald Trump has won the number of delegates needed to secure the Republican presidential nomination. The prospect has sparked as much controversy abroad as it has in the United States. Zlatica Hoke has more.
    Video

    Video Drawings by Children in Hiroshima Show Hope and Peace

    On Friday, President Barack Obama will visit Hiroshima, Japan, the first American president to do so while in office. In August 1945, the United States dropped an atomic bomb on the city to force Japan's surrender in World War II. Although their city lay in ruins, some Hiroshima schoolchildren drew pictures of hope and peace. The former students and their drawings are now part of a documentary called “Pictures from a Hiroshima Schoolyard.” VOA's Deborah Block has the story.
    Video

    Video Vietnamese Rapper Performs for Obama

    A prominent young Vietnamese artist told President Obama said she faced roadblocks as a woman rapper, and asked the president about government support for the arts. He asked her to rap, and he even offered to provide a base beat for her. Watch what happened.
    Video

    Video Roots Run Deep for Tunisia's Dwindling Jewish Community

    This week, hundreds of Jewish pilgrims are defying terrorist threats to celebrate an ancient religious festival on the Tunisian island of Djerba. The festivities cast a spotlight on North Africa's once-vibrant Jewish population that has all but died out in recent decades. Despite rising threats of militant Islam and the country's battered economy, one of the Arab world's last Jewish communities is staying put and nurturing a new generation. VOA’s Lisa Bryant reports.
    Video

    Video Meet Your New Co-Worker: The Robot

    Increasing numbers of robots are joining the workforce, as companies scale back and more processes become automated. The latest robots are flexible and collaborative, built to work alongside humans as opposed to replacing them. VOA’s Tina Trinh looks at the next generation of automated employees helping out their human colleagues.
    Video

    Video Wheelchair Technology in Tune With Times

    Technologies for the disabled, including wheelchair technology, are advancing just as quickly as everything else in the digital age. Two new advances in wheelchairs offer improved control and a more comfortable fit. VOA's George Putic reports.
    Video

    Video Baby Boxes Offer Safe Haven for Unwanted Children

    No one knows exactly how many babies are abandoned worldwide each year. The statistic is a difficult one to determine because it is illegal in most places. Therefore unwanted babies are often hidden and left to die. But as Erika Celeste reports from Woodburn, Indiana, a new program hopes to make surrendering infants safer for everyone.
    Video

    Video California Celebration Showcases Local Wines, Balloons

    Communities in the U.S. often hold festivals to show what makes them special. In California, for example, farmers near Fresno celebrate their figs and those around Gilmore showcase their garlic. Mike O'Sullivan reports that the wine-producing region of Temecula offers local vintages in an annual festival where rides on hot-air balloons add to the excitement.
    Video

    Video US Elementary School Offers Living Science Lessons

    Zero is not a good score on a test at school. But Discovery Elementary is proud of its “net zero” rating. Net zero describes a building in which the amount of energy provided by on-site renewable sources equals the amount of energy the building uses. As Faiza Elmasry tells us, the innovative features in the building turn the school into a teaching tool, where kids can't help but learn about science and sustainability. Faith Lapidus narrates.

    Special Report

    Adrift The Invisible African Diaspora