This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鶕 combines 音 (sound) and 鳥 (bird), likely a phono-semantic compound where 音 suggests the reading and 鳥 indicates a bird-related meaning. The exact historical development is uncertain.
A bird (鳥) associated with sound (音), perhaps a songbird, but its exact meaning is unclear.
For アン, imagine an answering bird: answer -> アン, and the bird on the right chirps back.