Researchers at Nagoya University found that roosters crow ahead of dawn because of an internal body clock, and that in a flock the top-ranking bird gets the first word. Keeping a few hens yourself? There is a rule to know too.
AI-generated image, not a photograph of a real person or place.
CROWS FIRST the top bird
A clock, not the sun
Rank sets the order
Register your flock
The science of the dawn crow
THE SHORT ANSWER
Roosters keep their own time.
The dawn crow is set by a body clock. In a flock, rank decides who goes first.
BODY CLOCK
Crowing before the light
Under 12 hours of light and 12 of dim light, roosters began crowing 2 to 3 hours before the lights came on. In constant dim light they kept a rhythm of about 23.7 hours.
A 2015 study found the top-ranking rooster always crowed first, then the others in descending order of rank. Remove him and the second-ranking bird took over.
Pick a situation to see what the GOV.UK guidance for England and Wales says. The bar shows how firmly the registration rule applies.
Based on GOV.UK guidance from Defra and the Animal and Plant Health Agency (APHA). Scotland has separate guidance. General information, not legal advice.
TWO NUMBERS WORTH KNOWING
A clock that runs close to a day.
From the 2013 Nagoya University study published in Current Biology.
2–3 hours
How early roosters started crowing
With 12 hours of light and 12 hours of dim light, crowing was observed 2 to 3 hours before the lights came on, so the birds were anticipating the day rather than reacting to it.
BEFORE DAWN
23.7 hours
Crowing rhythm in constant dim light
Kept in dim light all the time, roosters still crowed in a cycle of about 23.7 hours, a sign of an internal circadian clock.
FREE-RUNNING
Source: Nagoya University research highlight, Cock-a-doodle-doo: No Need for an Alarm Clock (2013).
FOR BACKYARD KEEPERS
A few hens, a few duties.
GOV.UK guidance sets out what keepers in England and Wales need to do, whatever the size of the flock.
Register within a month
Register within one month of keeping poultry. Without a CPH number you can register online, which GOV.UK says takes about 10 minutes.
Confirm every 12 months
After registering, confirm your details and the details of your birds to APHA every 12 months.
Report changes in 30 days
Tell APHA within 30 days if your contact details, species, purpose or numbers change, or if you stop keeping birds.
Think about neighbours
Noise from premises can be a statutory nuisance in England. Councils must investigate complaints and can serve an abatement notice.
AI-generated image, not a photograph of a real person or place.
THE PECKING ORDER
The boss bird speaks first.
AI-generated image, not a photograph of a real person or place.
Chickens form a linear and fixed hierarchy in small groups. In a 2015 study in Scientific Reports, the top-ranking rooster set the timing of the predawn crow, and the presence of a dominant rooster reduced how often subordinates crowed before dawn.
The lower-ranking birds could still crow: crows set off by outside sounds or light did not depend on rank. The researchers concluded that subordinates wait for the top bird's first crow every morning, compromising their own body clock for social reasons.
Questions
Questions people ask
Why do cockerels crow before dawn?
Research from Nagoya University, published in Current Biology in 2013, showed that the dawn crow is driven by the rooster's circadian clock. Under a 12-hour light and dim-light cycle, roosters began crowing 2 to 3 hours before the lights came on.
Do roosters crow when they hear other sounds?
Yes. The Nagoya University team found roosters crowed when given light or sound at various times of day, and concluded that crowing set off by outside stimuli is also regulated by the body clock.
Which rooster crows first in a flock?
A 2015 study in Scientific Reports found the top-ranking rooster always crowed first, followed by the others in descending order of social rank. When he was removed, the second-ranking rooster started the crowing.
Do I need to register a few pet hens?
In England and Wales, yes. GOV.UK says you must register within one month of keeping poultry or other captive birds at any premises, including birds you keep as pets. Scotland has its own guidance.
Why does registering matter?
GOV.UK says registered keepers are contacted by the Animal and Plant Health Agency with updates and guidance if there is a disease outbreak, such as bird flu, in their area.
