Roosters are the Perfect Alarm Clocks: They Don't Need the Sun to Crow

Roosters may just be the perfect alarm clock. New research has found that these male birds really do know the exact time of day due to their precise, internal clocks.

Previously, researchers weren't sure whether it was a rooster's internal clock that made him crow, or a change of light. Stimuli throughout the day, such as car headlights, will often set off a rooster's crow. Because of this, it was certainly possible that the crow was merely a response to increasing light.

"'Cock-a-doodle-do' symbolizes the break of dawn in many countries," said Takashi Yoshimura, one of the researchers, in a press release. "But it wasn't clear whether crowing is under the control of the biological clock or simply a response to external stimuli."

The study, published in the journal Current Biology, examined 40 roosters under lab conditions. Researchers placed the birds under constant light conditions and then recorded exactly when they crowed. The constant light didn't thwart the roosters, though. Without fail, the birds crowed each morning just before dawn.

The findings show that the rooster's crow is linked to a circadian rhythm. Circadian rhythm has been widely observed in plants, animals, fungi and even cyanobacteria. It helps regulate an organism's biological processes and links them to a certain time of day. Essentially, this means that the birds are genetically programmed to crow at a certain time. The rising sun set their internal clocks, causing them to crow every 24 hours.

Yet these findings aren't just relevant for roosters and chickens. They could allow researchers to determine the genetic underpinnings of other animal sounds, such as a dog's bark or a cat's meow.

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

The team plans to conduct future research on these genetic underpinnings as a follow-up to their current study.