Roosters don’t just crow at sunrise because the light wakes them up. They run on an internal alarm clock. Experiments show that even in total darkness, a rooster will still announce the morning on schedule, thanks to a built-in circadian rhythm. The call is not only a wake-up song but also a way to mark territory and tell other birds, “I’m in charge here.”

They are not alone in keeping time with nature. Songbirds begin their dawn chorus as the first rays hit the trees, wolves lift their heads to howl under a rising moon, and frogs start their twilight choirs. Across the animal kingdom, voices rise and fall with our world as it spins, reminding us that many creatures live by rhythms as old as the planet itself.