shrike
鴃 refers specifically to a shrike, a type of bird known for impaling prey on thorns.
鴃 combines 鳥 (bird) with 夬, which likely contributes the sound. The exact historical development of the phonetic component is uncertain.
The bird radical 鳥 on the left tells you it's a bird, and the right side 夬 looks a bit like a thorny branch, reminding you of the shrike's habit of impaling prey.
For ケイ, imagine a shrike perched on a gate (門, ケイ in some compounds) singing a sharp call: gate -> ケイ, and the bird is a shrike.
barbarian jabbering