anthus, skylark
鷚 centers on a small, ground-dwelling songbird: the pipit (anthus) or skylark. The two given meanings are closely related bird species.
鷚 combines 鳥 (bird) with 翏, which likely contributes the sound. The character was created to name a specific type of bird, the pipit or skylark.
The left side 翏 looks like feathers and wings, and the right side 鳥 is a bird. Together they form a small songbird with distinctive plumage: a pipit or skylark.
For リュウ, imagine a skylark singing a long, flowing melody: the sound 'ryuu' (like a musical flow) cues リュウ, and the bird's song flows upward.