The “scientific” term is “flightless birds.” In science it’s often important to be more specific about things than in everyday speech, which is why there are so many obscure “scientific” words, but when a “plain English” word is good enough, scientists are usually happy to use it. read more
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). read more