call
鷕 centers on a bird's vocal call. The single given meaning 'call' is specifically the sound a bird makes.
鷕 combines 唯 (which likely provides the sound) with 鳥 (bird), suggesting a bird-related sound or call. The exact historical development is uncertain.
A bird (鳥) on top of a sound (唯) — imagine a bird opening its beak (口) to call out.
For ヨウ, picture a bird calling out 'Yo!' as a greeting: Yo -> ヨウ, and the bird's call echoes.