This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鶎 combines 宗 and 鳥, but its exact historical development is uncertain. It may be a kokuji created in Japan for a specific bird name.
The kanji visually contains 宗 (sect, religion) and 鳥 (bird), but no clear meaning emerges from these parts alone. Its meaning is uncertain.
For キクイ, imagine a rare bird named Kikui that belongs to a secret sect (宗): Kikui -> キクイ, and the bird (鳥) is its symbol.