It's four A.M. You're tucked safely into a warm bed, savoring the last few hours of sleep before daybreak. And then, suddenly... a rooster crows.

It must be time to wake up, roll out of bed, and tend to the farm. Except it's four A.M., it's still dark out, and you're not a farmer.

It's that neighbor of yours, the one that for some unimaginable reason keeps a rooster as a pet. A rooster that flaunts the most basic rules of neighborhood etiquette by crowing every morning before sunrise. What gives?

Most people assume that roosters are programmed to crow at the first sign of sunlight to announce the dawning of a new day, or some such romantic notion.

Like all birds, roosters call in a daily cycle determined by circadian rhythms. That is, a rooster's internal clock allows it to anticipate the sunrise and prepare for another exciting day of looking for food.

But why must roosters crow as they prepare to start their day, and why do some roosters sound off before dawn? Roosters are territorial creatures and don't much like other roosters trespassing on their land.

They crow in order to establish their domain and warn other roosters to stay away or prepare to brawl. Because their internal clocks are sometimes set a bit early, some roosters begin crowing well before sunrise.

So what can you do if you live near a rooster, or have a pet rooster but don't want to be the neighborhood pariah? Short of castration, not much. Yes, castrating a rooster will curb its crowing, but that's a fairly drastic measure to stop a few cock-a-doodle-doos.