the southern cassowary ("casuarius casuarius"), also known as double-wattled cassowary, australian cassowary or two-wattled cassowary, is a large flightless black bird. it is one of the three living species of cassowary, alongside the dwarf cassowary and the northern cassowary. it is a ratite and therefore related to the emu, ostriches, rheas and kiwis.