Flightless bird 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 duck, have lost
Largest prehistoric animals size. Total length was probably up to in female and they weighed about . The largest extinct "Titanohierax" was a giant hawk about 8 kilograms that lived in the Antilles, where it was among the top predators. The largest-known in this group was a giant flightless "Sylviornis", a bird long and weighing up to about . The largest-known songbird is the extinct giant grosbeak ("Chloridops regiskongi") at long. The largest-known cormorant was the spectacled cormorant of the North Pacific ("Phalacrocorax perspicillatus"), which became extinct around 1850, was larger still, averaging around and . The largest-known in this group—which has been