male mandarin duck
鴛 refers specifically to the male mandarin duck, a bird known for its striking plumage and strong pair bonds.
鴛 combines 夗 (likely a phonetic component) with 鳥 (bird) to denote a specific type of duck. The exact historical development of 夗 is uncertain.
The top part 夗 looks like a curled-up shape, and the bottom is 鳥 (bird). Imagine a male mandarin duck with its distinctive curled feathers on display.
For エン, picture a male mandarin duck floating peacefully at the end of a pond: end -> エン.