Geographic variation is confused. Clements recognizes seven subspecies while HBW and IOC recognize six and HBW suggests that more than one species may be involved.
Based on published ranges, this is Pycnonotus goiavier jambu which occurs from s Burma to s Indochina. This race is said to be darker and more tawny than Pycnonotus goiavier personatus (analis is a synonym) which replaces it on the Maylayan Peninsuala to the south. Comparison with photos of presumed personatus/analis from Maylasia and Singapore show those birds to be somewhat whiter and less dingy on their underparts than our bird.
This bird is an adult. Juveniles have a less distinct head pattern. Although reported to be common and increasing throughout its range, we only encountered this bird a few times on our visit.
The name Yellow-vented Bulbul is also sometimes applied to a different species the White-spectacled Bulbul. (Pycnonotus xanthopygos) of the Middle East.
Digiscoped with Panasonic DMC-LX5 | Nikon FieldScope III | 30XWA |hand-held (no adapter).