This is a clone technique utilised by Itachi Uchiha.
A technique that produces a clone by projecting one's own chakra towards dozens of crows. Because it uses crows as a medium, it requires less chakra than the normal Shadow Clone Technique, while still being able to perform techniques. The dozens of crows then come together to form the body of a clone. The same crows of the dispersed clone can regroup and form a new clone immediately.
When the chakra projected by the user is severed, the crows disperse, though the user is still able to continue to speak through it. When the crow clone is defeated, the crows can regroup to form a new clone immediately, or failing that, can be used to blind the opponent, leaving them open to a counter-attack.
- Sha no Sho, page 242