Kenku

The Kenku have no language. They communicate through telepathy. Little is known about their communication except that can use mental imagery to convey complicated ideas in an instant. As their language is one of the mind, it has no spoken or verbal elements. It cannot be learned by any who do possess the facility for telepathy. It is rumored, however, that they can use this "language" to communicate with any sentient being.

Language Group
The Tribal and Unclassifiable Languages
Written Form
None
Commonly Spoken In
The Flocks of the Shi-Loft Mountains