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
African jacana evolved due to a combination of two factors: firstly, the lakes that the jacana lives on are so resource-rich that the relative energy expended by the female in producing each egg is effectively negligible. Secondly the jacana, as a bird, lays eggs and eggs can be equally well incubated and cared for by a parent bird of either gender. This means that the rate-limiting factor of the jacana's breeding is the rate at which the males can raise and care for the chicks. Such a system of females forming harems of males is in direct contrast to the more usual