Birdsong by a Mystery Bird-So Beautiful

Last week I was outside early and this was what I heard.

I can recognize the Western scrub jay's screeching and the crow cawing, but I do not know what bird has the very long complicated birdsong starting at about 20 seconds on the video. Even looking with my binoculars I could not see the bird who was serenading me on this autumn morning.

If anyone knows who the mystery bird is, please leave me a comment or email me with your ideas.

Barb-Harmony Art Mom