The term CASSOWARY RELATIVE refers to two large flightless birds, the RHEA (4 letters) and the EMU (3 letters). Both birds are native to Australia and New Zealand and are closely related to the cassowary. The RHEA is the largest bird in South America and is similar in size to an ostrich. The EMU is the second-largest bird in Australia and is the only extant member of the genus Dromaius. Both birds are omnivorous and feed on a variety of plants and insects.