Pilots’ actions after the bird strike are an early focus of the investigation, according to people familiar with the probe.

The exact cause of the Jeju Air crash remains unclear, and the investigation is complicated because the black boxes stopped recording four minutes before impact.

South Korean officials investigating the fatal Jeju Air crash have published a preliminary report of the accident.

Authorities have suggested that migratory bird strikes were the cause of last month's deadly plane crash in South Korea, according to multiple reports.

The first report on last month’s Jeju Air crash in South Korea has confirmed traces of bird strikes in the plane’s engines, though officials haven’t determined the cause of the accident that killed all but two of the 181 people on board.

South Korean authorities have submitted a preliminary report on last month's fatal Jeju Air crash to the International Civil Aviation Organization. The ongoing investigation focuses on a 'bird impact' as well as examining the aircraft's engines and landing systems.

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.

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. Julian Satterthwaite reports.

Bird feathers and bloodstains were found in both engines of the Jeju Air plane that crashed in December, according to a preliminary investigation

The first report on last month’s Jeju Air crash in South Korea confirmed bird strikes in the plane's engines, though officials haven't determined

Bird feathers were found in the engines of crashed Jeju Air jet. Investigators claim they have found evidence of a bir