A rooster crows because he has an internal clock that helps him anticipate sunrise. Like all birds, roosters sing – or crow – in a daily cycle. Almost all animals have daily cycles of activity known as circadian rhythms that roughly follow the cycle of day and night. Roosters anticipate sunrise to get a head start on their daily hunt for food and defense of territory.
But if one rooster in the neighbor has an internal clock that’s set a little early, he can stimulate other roosters to crow early, too. The rooster’s sunrise song is actually a way of establishing his territory. When a rooster crows, he’s sending a signal to other roosters that if they trespass, they’re asking for a fight.
A rooster will often crow from a vantage point above his territory so he can make others more aware of his presence and so that his songs travel farther. Even though roosters are the most famous crooners of the chicken world, hens aren’t exactly silent, either. When a hen spots a hawk, she’ll let out a harsh scream to send her chicks into hiding. But if she sees a less-threatening human, she might just cackle.