There were still many articles out there linking Javan Myna with White-vented myna. Most of the new version of field guides have actually differentiated the two birds. One of the ways to determine the differences between the 2 morphs is to look at its crest. Javan Myna has a shorter crest while the latter has more fluffy and longer crest. Then one might also want to compare Javan Myna with Crested Myna. Crested Myna has a shorter crest quite similar as a Javan but Crested Myna has a slaty-black undertail-coverts and a bill which is a pale whitish yellow almost to ivory color as compared to yellow bill and a clean white vent of a Javan . One could also mistakenly id Javan Myna as a Jungle myna. From field observations, one of the easiest way to diffentiate the two birds is to look at its bills - a jungle myna has an orange bill with bluish base while a Javan myna and White-vented myna have yellow bills.
However recently (2012) i met with a seasoned birder named Yang Chong and some experience birders like Aun Tiah and Mr Rafi who informed me that the bluish tinge at the base of Jungle Myna may not always be there. So the other way to differentiate between Javan and Jungle i guess is to see the back feathers whereby Javan has slaty black while jungle has brown back.
This is the first pair (above image) which i would label as "Bird A"
2nd pair as per images below ("Bird B")
They (Bird A & B) were actually different birds
This one has a white color mouth roof (Bird B).
....and this one was darker! (Bird A)
Interesting ya !
Interesting ya !