The feathers and blood stains on both engines of the Jeju Air plane were from the Baikal teal, a type of migratory duck that flies in large flocks, according to a preliminary investigation report published on Monday.

A preliminary report published on Monday, Jan. 27, said feathers and blood stains were found in both engines of the Boeing 737-800 that crashed at Muan International Airport airport on Dec. 29, according to CNN and the BBC.

Bird feathers and bloodstains were found in both engines of the Jeju Air plane that crashed in December, according to a preliminary investigation released Monday. Both engines recovered from the crash site were inspected,