I haven't looked at your link Ravi, but the whole idea of vultures dying from Diclofenac sounds really far fetched to me. Snopes will put the matter to rest, am sure.
The Parsees so called because they came to India from Persia were Zoroastrians that fled Iran from conflict with the new Islamic fervour sweeping the region and the oppressive Jaziya tax that the new rulers imposed on non converts. In India, they have thrived for centuries and are amongst the richest and most literate communities there.
I am uncertain if ALL Zoroastrians follow the excaration that is described here, but the Parsees in India certainly do. The excarnation sites are called 'Towers of Silence' and are themselves rather expensive to build.
For Zoraoastrians the elements, fire, earth, water, wind are very sacred and this method is chosen to prevent defiling the environment. I can imagine that this will open up a Pandora of questions, but this is all I know.
I recently read a book, In search of Zarathustra. There is a lot in the book on the 'heretic' cults of Mithraism and Minocheanism (I just KNOW that I got that spelling all wrong), thier roots in Zarathushtra and the strong influence of Zoroastrianism on the religious beliefs of Europe in the middle ages. Splendid read
