the owl
鶹 refers specifically to the owl, a nocturnal bird of prey.
鶹 is a phono-semantic compound combining 鳥 (bird) with 留, which likely provides the sound リュウ and may suggest the owl's characteristic stillness or perching behavior.
The left side 留 can be thought of as a bird that stays still, like an owl perched quietly. The right side 鳥 confirms it's a bird. Together, 鶹 is the owl.
For リュウ, imagine an owl hooting a low, resonant 'ryuuu' sound in the night: ryuu -> リュウ.