kind of hawk
鶗 refers to a specific kind of hawk. The meaning is narrow and does not extend to broader bird-of-prey concepts.
鶗 combines 是 (likely a phonetic component) with 鳥 (bird), forming a character for a specific bird of prey. The exact historical development is uncertain.
The left side 是 looks like a perch, and the right side 鳥 is a bird. Picture a hawk perched on a branch, watching for prey.
For テイ, imagine a hawk taking off from a table (テーブル): the first syllable テー cues テイ, and the hawk launches into the air.