Book 31, Question 90
Why do roosters crow in the morning?
Roosters have an internal body clock.
In experiments, roosters kept in steady dim light still crowed at the same time each morning, about when the sun would be coming up. A crow also lets other roosters know where he is, and nearby roosters often answer. The loudest, highest-ranking rooster in a flock tends to crow first. Light and sounds from the rest of the farm can also set them off.