Chlidonias, often known as the marsh terns, is a genus of birds in family Laridae. 
The birds are found in freshwater marshes, rather than coastal locations. 
The genus name Chlidonias is from Ancient Greek khelidonios, "swallow-like", from khelidon, "swallow".

1/ Whiskered tern (Nhàn đen, Chlidonias hybrida)
The specific hybridus is Latin for hybrid.

2/ White-winged tern, or white-winged black tern (Nhàn xám, Chlidonias leucopterus or Chlidonias leucoptera)