Do you like the song "How High the Moon?" So did Charlie Parker. He wrote Ornithology using exactly the same changes as "How High the Moon." Parker's melody is completely different, and usually played at a blindingly fast bebop tempo.
The title of this song is tongue-in-cheek. Charlie Parker's nickname was "Bird" and ornithology is the study of birds.
The biggest challenge of this song is probably the tempo. This arrangement is set at 190, which is quick, but the song is often played at 220 or higher. The song form is a fairly convention 32-bar ABAB, although the B sections are not identical.
If you find it overwhelming to improvise these changes at this speed, don't despair, Just practice the head until you can play that at 190. Try practicing the improvisation on "How High the Moon". That will be easier because it is a more relaxed tempo. The commentary on "How High the Moon" includes tips useful for improvisation.