Why do birds chirp when the sun comes up?

Question

Any ideas?

Answer 1

Usually because they're territorial and trying to attract mates. The phrase "early bird gets the worm" also rings true; those that start singing earlier are more successful at attracting mates. It's also too hot later in the day.

Answer 2

They want everybody to know that they are still there, and they have the same territory as yesterday. They will notice if any same-species birds don't check in, and may move into the missing birds territory which is now vacant.