flightless bird

King penguins (Aptenodytes patagonicus).Penguins are a well-known example of flightless birds. An Okarito kiwi (Apteryx rowi), also known as the rowi Common ostrich (Struthio camelus). Ostriches are the largest extant flightless birds as well as the largest extant birds in general. An extinct moa. Until the arrival of humans, New Zealand's only mammals were bats and seals, resulting in many bird species evolving to fill the open niches. While many of New Zealand's flightless birds are now extinct, some, such as the kiwi, kākāpō, weka, and takahē have survived to the present day.

Flightless birds are birds that cannot fly, as they have, through evolution, lost the ability. There are over 60 extant species, including the well-known ratites (ostriches (Struthio), emus (Dromaius), cassowaries (Casuarius), rheas, kiwis (Apteryx)), and penguins (Sphenisciformes). 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 in general, is the common ostrich (2.7 m, 156 kg).