Sulphur-breasted Warbler 
(Chích ngực vàng, Phylloscopus ricketti)

The sulphur-breasted warbler (Phylloscopus ricketti) is a species of Old World warbler in the family Phylloscopidae. 
This bird breeds in China; it winters to Laos, Thailand and Cambodia.

Leaf warblers are small insectivorous passerine birds belonging to the genus Phylloscopus. 
Leaf warblers were formerly included in the Old World warbler family but are now considered to belong to the family Phylloscopidae, introduced in 2006.
The name Phylloscopus combines the Ancient Greek phullon meaning "leaf" and skopos meaning "seeker" (from skopeo, "to watch").