The Purple Swamphen (Porphyrio porphyrio) [now Grey-headed Swamphen (P. poliocephalus)] is primarily a vegetarian, taking any and all parts of aquatic and semi-aquatic plants. At the same time it takes animal food that includes various invertebrates like small crabs, snails LINK, insects and their larvae, fish, frogs, lizards, snakes and nestlings.
Its large bill is used to dig and pull plants while its prominently long toes come in useful in gripping vegetation and transferring it to its mouth LINK.
The above video clip by Jeremiah Loei, documented at Singapore’s Tampines Eco Green, shows the Purple Swamphen pulling and eating the Greater Kyllinga (Kyllinga polyphylla, Family Cyperaceae) – previously known as Cyperus aromaticus. Note that in the video the swamphen rips the flowering stalks of the semi-aquatic sedge, eating only the tender lower bases.
Credit: Jeremiah Loei (image, video), YC Wee (text).
Robson, C., 2008. A field guide to the birds of South-east Asia. New Holland, London. 544 pp.