The Grey-headed Purple swamphen (Porphyrio poliocephalus) occurs in India to Sri Lanka, southern China, northern Thailand, Andaman and Nicobar islands.
Some authors classify this bird as one of 13 subspecies of the Purple Swamphen (Porphyrio porphyrio) which differ mainly in plumage colour.
In this case, the subspecies groups are: P. p. porphyrio in the Mediterranean, P. p. madagascariensis in Africa, P. p. poliocephalus in tropical Asia, P. p. melanotus in much of Australasia, P. p. indicus in Indonesia and P. p. pulverulentis in the Philippines. European birds are overall purple-blue, African and south Asian birds have a green back, and Australasian and Indonesian birds have black backs and heads.