Field Sparrow plastic complex song

Each adult male Field Sparrow sings one simple song (the regular daytime, bouncing ball song) and one complex song, usually sung only at dawn (the complex song is occasionally heard during the day in aggressive interactions).
I obtained the following recording of a (presumed) young Field Sparrow practicing its dawn song in mid-morning earlier this week. The phrases are each different, typical of plastic song before it has become crystallized into the final version. At 63s and 68s there are two slightly different versions of the simple song.
(Mar, PA)

complex songs:

simple songs: