The Black Kite (Milvus migrans) is found in Europe, Asia, Africa and Australia.
The numbers in Europe and Africa are small but in South Asia it is an abundant bird.
There are five subspecies of the Black Kite.
The subspecies occurring in North Vietnam is Milvus migrans lineatus, sometimes also referred to as the Black-eared Kite.
There have been some suggestions that Milvus migrans lineatus should be elevated to a full species status.

La Han Bay, Cat Ba Island, Vietnam, 4 & 5 January 2024