I don't have an extensive library so am not sure on what basis those who separate White-headed (Himantopus leucocephalus) from Black-winged Stilt (H. himantopus) do so. White-headed is an Australasian taxon which certainly breeds in Java and other Indonesian islands, and has been claimed in Borneo, including Sabah and Sarawak.
The problem with identifying White-headed is the variability of plumage shown by Black-winged in South-east Asia. Here's a pic taken at Pulau Burung, Penang, in 2008.
So this visit gave me chance to take another look at White-headed Stilts.
There doesn't seem to be much difference between the sexes.
The juveniles I saw had significantly less buff fringing to the upperparts (compare with this pic taken in Penang)
Almost all the birds in the colony had white heads and extensive black manes, except for this bird.
I made some recordings of the calls, which, according to Susan Myer's Field Guide to the Birds of Borneo, is slightly higher-pitched than that of Black-winged, so I'll check this out next time I visit Pulau Burung.
Some more pics:
Overall, I came away wondering why this is considered (by some) to be a different species from Black-winged. A glance through the images of Black-winged on the Oriental Bird Image database shows that the species exhibits such a variety of plumages over its wide range, and the difference in neck markings appears to be clinal...