system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What the hell are birds doing screaming at 5am?
gpt
There are multiple theories but the most accepted one is that it allows the song to travel farther. The morning air is cooler and drier, meaning sound can travel at a higher range.

As for why they are singing it's likely male birds establishing their territory and warning other males away.