By Jack Kim SEOUL (Reuters) -Both engines of the Jeju Air plane that crashed last month contained duck remains, according to a preliminary report on Monday, with authorities still trying to determine what caused the deadliest air disaster on South Korean soil.

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

Feathers and blood stains discovered on both engines of the Boeing 737-800 were identified as coming from a Baikal teal, a type of migratory duck, according to a preliminary investigation report released on Monday.