Chestnut-headed bird

The birds in Vietnam with a chestnut head could be:

1/ Chestnut-headed tesia (Cettia castaneocoronata)

The birds in Vietnam with a rufescent head (or a rufous head, or a reddish brown head, or a chestnut head, or a brown head) could be:

1/ Rufous-headed parrotbill (Paradoxornis bakeri), 
or greater rufous-headed parrotbill

2/ Short-tailed parrotbill (Suthora davidiana)

Both these two birds could have brownish head, rufous head or reddish brown head.

The difference between Rufous-headed Parrotbill and Short-tailed Parrotbill in Vietnam:

1/ Rufous-headed parrotbill (Paradoxornis bakeri), or greater rufous-headed parrotbill,

- Longer tail length per body;

- Whitish or beighe throat

2/ Short-tailed parrotbill (Suthora davidiana)

- Shorter tail length per body;

- Black throat