This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鸊 combines 辟 (likely phonetic) with 鳥 (bird). It is associated with a type of waterbird, but the exact historical development is uncertain.
The left side 辟 looks like a wall or enclosure, and the right side 鳥 is a bird. Picture a rare bird hiding behind a wall, its meaning unclear.
For ヘキ, imagine a bird making a 'heki' sound as it calls from behind the wall: heki -> ヘキ.