Flightless bird that require a significant amount of overall metabolic energy, ratites decrease their basal metabolic rate and conserve energy. A study looking at the basal rates of birds found a significant correlation between low basal rate and pectoral muscle mass in kiwis. On the contrary, flightless penguins exude an intermediate basal rate. This is likely because penguins have well-developed pectoral muscles for hunting and diving in the water. For ground feeding birds, a cursorial lifestyle is more economical and allows for easier access to dietary requirements. Flying birds have different wing and feather structures that make flying easier, while flightless birds'
Southern cassowary occurrence range of , and between 10,000 and 20,000 birds were estimated in a 2002 study, with between 1,500 and 2,500 in Australia. Southern cassowaries have been bred in many zoos around the world, like at White Oak Conservation in Yulee, Florida, United States. Southern cassowary 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 a ratite and therefore related to emu, ostrich, and the "Rhea" and Kiwi genera. (See also dwarf cassowary and northern cassowary.) Presently, most authorities consider the southern cassowary monotypic, but several