Pale-Legged Leaf Warbler 
(Chích chân xám, Phylloscopus tenellipes)

The pale-legged leaf warbler (Phylloscopus tenellipes) is a species of Old World warbler in the family Phylloscopidae. 

The name Phylloscopus combines the Ancient Greek phullon meaning "leaf" and skopos meaning "seeker" (from skopeo, "to watch").
tenellipes Latin tenellus delicate; pes foot.