If you’re a bird, particularly a male bird, you try your hardest to impress the ladies of your species and intimidate the other males. If it’s too dark to go looking for your breakfast, you may as well sing! And if you can sing a louder, sweeter song than your rival males, then all the better.
Singing also helps everyone to understand who’s around the neighborhood and what area is their territory (their home). Each bird has their own version of the song they sing that makes it unique to them. It’s how the birds know who is around! One bird might sing, “trill tweet tweet trill,” but another may sing, “tree tweet tweet tree.”
Think of it like driving down your street and seeing your friend’s house. You know it is their house because you live in that neighborhood and recognize the way your friend’s family decorates.
So why do the birds sing a dawn chorus every day? To stay in touch!
The louder your song the better your chances of letting everyone else know you’re around. A bird’s song is like a signature to them and it is just as unique as the sound of each of our own human voices.