The southern cassowary is the largest forest bird in the world, and the second heaviest bird in the world after the ostrich. It is third tallest after the ostrich and emu. Females are bigger and more brightly coloured. Adult Southern Cassowaries are between to tall. Some females may get as big as , and weigh about . They do not have feathers on their necks. The necks are brightly colored in red, blue, purple and yellow. The southern cassowary has two wattles, loose skin, which hangs down from their neck. The Northern Cassowary has one wattle. The Dwarf Cassowary has no wattles.