First i thought, there were more than two birds, they can't sleep and talking together, but it was only one, who makes that beautiful noises.
Have you ever heard a nightingale?
Two weeks ago, a nightingale moved into my tree in front of the window of my sleepingroom. Since then, the bird sings me to sleep. Very pretty, i tell you and i will miss it when the bird get's mute in june.
If you will listen: