Wake up early enough and depending on where you live, you’ll likely hear a pleasant chorus of birds chirping their tiny hearts out. This a.m. avian arrangement is instinctual behavior for birds, but why? What prompts them to begin their bird bellowing in the morning?

According to WIRED, this early singing is known as the dawn chorus, and it can start as early as 4 a.m. and last for several hours. Birds do it to attract mates and warn other birds to avoid their turf. One theory as to why they opt for the wee hours to communicate these important messages is because the low visibility makes it hard to do other bird activities, like foraging. Keeping their activity level low, they opt to sing instead.

Another theory argues that birds use the morning vocals to project an image of strength. By singing with fervor, they’re letting other birds know they survived the night—no guarantee in nature—and would make for an excellent mate.

Like a good recording studio, the early morning hours also allow birds to transmit a clear tune thanks to the cooler, drier air. Because birds have distinctive chirps, that clarity helps them be more easily identified by birds within listening distance.

There used to be a prevailing theory that birds sang so much in the mornings because the sounds could travel farther due to less atmospheric turbulence, but that was debunked by researchers at the University of Western Ontario back in 2003. They played recordings of sparrows at dawn and midday. The songs didn’t move farther, but they were more consistent.

Because birds only have so much energy to belt one out, singing when they stand the best chance of being heard makes sense. For a bird, an early morning session is like having the perfect acoustic environment for their performance.

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