Of course, I watched birds in Viet Nam too. We went to Cuc Phuong national park, which is three hours drive from Hanoi. We didn't have neither a guide nor a vietnamese birds guidebook. But Thai birds' book was really useful.
One of the most common birds in Cuc Phuong. We kept saying that "No more Black-crested Bulbul nor Red-whiskered Bulbul!" Because there were so many of them. But once back in Japan, I want to see them again...