Blue-Headed Double-Wattled Cassowary or Southern Cassowary (Casuarius casuarius), Jurong Bird Park, Singapore
The cassowaries are ratites (flightless birds without a keel on their sternum bone) in the genus Casuarius and are native to the tropical forests of New Guinea, nearby islands, and northeastern Australia. The southern cassowary is the third tallest and second heaviest living bird, smaller only than the ostrich and emu.
The Southern Cassowary has a soft and spongy casque that they use as a tool to forage for food, and as a weapon against rivals. It is also believed that the casque may be useful for them to receive sounds or to communicate.
Sources: Wikipedia and birdpark.com.sg