bird resembling the crane
鵾 refers to a specific bird that resembles a crane, likely a large wading bird with similar long legs and neck.
鵾 combines 昆 (phonetic component) with 鳥 (bird), indicating a bird whose name sounds like 昆. The exact historical development is uncertain.
The left side 昆 suggests a group or swarm, and the right side 鳥 is a bird. Imagine a flock of crane-like birds gathering together.
For ウン, picture a crane-like bird letting out a deep 'un' sound as it calls across the marsh: 'un' -> ウン.