beak
咮 centers on the beak of a bird, the hard projecting mouthpart.
咮 combines 口 (mouth) with 朱, which likely contributes the sound. The character is used specifically for a bird's beak.
The mouth radical 口 beside 朱 suggests a specialized mouthpart. Picture a bird's beak as a red (朱 can suggest vermilion) pointed mouth.
For トウ, imagine a toucan's beak: toucan -> トウ, and the beak is the bird's prominent mouth.