This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 鴘 is uncertain. It combines 鳥 (bird) with 弁, but the original semantic or phonetic role of 弁 in this character is unclear.
The kanji has 鳥 (bird) on the right and 弁 on the left, but without a clear meaning, it is hard to create a reliable mnemonic. Perhaps imagine a bird with a distinctive弁-shaped crest, but treat this as purely speculative.
For ヘン, picture a hen with a 弁-shaped comb: hen -> ヘン, and the bird shape ties it to the kanji.