This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鵔 is a phono-semantic compound combining 鳥 (bird) with 夋, which likely provides the sound. The exact historical development is uncertain.
The left side is 鳥 (bird) and the right side is 夋. Since the meaning is unclear, you can think of it as a mysterious bird with an unusual shape.
For シュン, imagine a bird that makes a 'shun' sound as it flies away quickly: shun -> シュン.