all the sounds of earth are like music

i noticed the songs of the birds outside my window have begun to change.
i used to hear only a shrill chirp that bordered on a screech. sometimes as soon as 3 am. lately i've heard a much more melodic and cheerful song (each song being improvised on the spot and unique from every song before and every song that will ever be sung.)
i like to say the birds have begun to change their songs.
alex pointed out that it's probably the bird population that's changing.
i still like to say the birds have begun to change their songs. collectively. like a choir when the altos take the melody from the sopranos.