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'
Birds of Australia Birds of Australia Australia and its offshore islands and territories have 898 recorded bird species as of 2014. Of the recorded birds, 165 are considered vagrant or accidental visitors, of the remainder over 45% are classified as Australian endemics: found nowhere else on earth. It has been suggested that up to 10% of Australian bird species may go extinct by the year 2100 as a result of climate change. Australian species range from the tiny 8 cm weebill to the huge, flightless emu. Many species of Australian birds will immediately seem familiar to visitors from the Northern Hemisphere - Australian