This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鳹 combines 今 and 鳥, but the exact historical development and original meaning are uncertain.
The left side 今 (now) and right side 鳥 (bird) suggest a bird of the present moment, but the actual meaning is unclear.
For ケン, imagine a bird named Ken pecking at the ground: Ken -> ケン, and the bird shape 鳥 is on the right.