My two Delaware Roosters usually start soon after 3:30am, but I think that may be because I get up at 3:30am, and they probably see the light from the house. I read in a few articles that said scientists really don't know why roosters seem to crow more as the sun is about to come up.
But, according to a GRIT Magazine article:
Turns out the answer is simpler than you might think. First, roosters crow all the time. The connection with the sun coming up is a misconception. “They might, on occasion, crow right at dawn. But it’s just a coincidence,” Pete Alcorn (
TransitionsAbroad.com) says. “Roosters crow whenever they feel like it: morning, noon and night, not to mention afternoon, evening and the parts of the day that don’t have names.”
Roosters crow because they hear other roosters crowing, to show that a certain place in the barnyard is their turf, to try and assert their authority over another rooster, or even to gloat when a hen cackles after laying an egg. Joe Faust, the Accidental Farmer (
JoeCliffordFaust.com/chickens), says, “I think the general rule for this is that a rooster crows any time it wants to – or feels the need. For all I know, mine may crow on and off all night, but I just hear them in the morning.”
As a diurnal animal (one that is active during the day), the rooster starts his daily doings when the sun comes up. If you think about early morning, it’s almost always associated with bird song. Most birds seem to spend time shouting their messages to the world in the morning, and chickens are no different.
David Feldman addresses this question in When Do Fish Sleep? He quotes Janet Hinshaw of the Wilson Ornithological Society who says, “Most of the crowing takes place in the morning, as does most singing, because that is when the birds are most active, and most of the territorial advertising takes place then. Many of the other vocalizations heard throughout the day are for other types of communication, including flocking calls, which serve to keep members of a flock together and in touch if they are out of sight from one another.”
The reason that we associate a rooster’s crow with the dawn is most likely because that’s when it’s most noticeable to our sleepy selves. When the relative quiet of night is disturbed by the local rooster, we sit up, take notice, and maybe grumble a little on the way to the barn.