Why roosters crow at dawn
Bird has in-built ‘clock’ and light conditions make no difference
[attach id="242686" size="medium"]Roosters have very good time-keeping abilities. Photo: PA[/attach]
Roosters have a built-in alarm clock that ensures they crow at dawn, a study has found.
Scientists in Japan placed birds in continuously dimly lit conditions and discovered it made no difference to their timekeeping.
They kept on crowing each morning just before dawn, showing that the behaviour is not triggered by darkness giving way to daylight.
Cockerels are known to perform at other times of day besides the morning, giving rise to uncertainty about how crowing is controlled.
“Cock-a-doodle-doo symbolises the break of dawn in many countries,” said study leader Takashi Yoshimura, from 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.”
The new research suggests that it is primarily governed by an internal ‘circadian’ clock.
Light intensity increased the number of crows in a dose-dependent manner, according to the findings published in the journal Current Biology.
Crowing is believed to be a territorial warning signal aimed at other males that might pose a potential threat. Roosters crow more when there are other cockerels around.
Crowing is believed to be a territorial warning signal aimed at other males that might pose a potential threat
The study is part of an ongoing investigation of rooster vocalisations, which are not learned like bird song or human speech.
“We still do not know why a dog says bow-wow and a cat says meow,” said Yoshimura. “We are interested in the mechanism of this genetically controlled behaviour and believe that chickens provide an excellent model.”