Flightless bird also included here. Flightless bird Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species including the well known ratites (ostrich, emu, cassowary, rhea and kiwi) and penguins. The smallest flightless bird is the Inaccessible Island rail (length 12.5 cm, weight 34.7 g). The largest (both heaviest and tallest) flightless bird, which is also the largest living bird, is the ostrich (2.7 m, 156 kg). Ostriches are farmed for their decorative feathers, meat and their skins, which are used to make leather. Many domesticated birds, such as the domestic chicken and domestic
Tasmanian emu agreed with the mainland birds in measurements and the external characters used to distinguish it—a whitish instead of black foreneck and throat and an unfeathered neck—apparently are also present, albeit rare, in some mainland birds. There are suggestions the bird was slightly smaller than the modern emu, but in conflict, other evidence (including descriptions of Pleistocene remains) indicates that both are similar in size. Today, it is apparently only known from subfossil bones, the skins which once existed having been lost. The Tasmanian emu was, as the mainland birds, hunted as a pest. In addition, the practice of setting fire