Before alarm clocks jolted us awake to an abrupt start to our day, roosters let us know the day had begun. How do roosters know it’s time to perform their daily duty? Researchers at Nagoya University discovered that it isn’t the light that triggers their crowing. They found that rooster’s internal clocks take precedence over external cues. If there are multiple roosters, the highest ranked rooster is the one who makes the initial crow. Once he signals that the day has begun, the other roosters follow with their own round of crows.