Flightless bird requirement for flightlessness. The kiwi does not exhibit gigantism, along with tinamous, even though they coexisted with the moa and rhea that both exhibit gigantism. This could be the result of different ancestral flighted birds arrival or because of competitive exclusion. The first flightless bird to arrive in each environment utilized the large flightless herbivore or omnivore niche, forcing the later arrivals to remain smaller. In environments where flightless birds are not present, it is possible that after the K/T Boundary there were no niches for them to fill. They were pushed out by other herbivorous mammals. New Zealand had
Cuban flightless crane sandhill crane endemic to the country. Cuban flightless crane The Cuban flightless crane ("Grus cubensis") is a large, extinct species of crane that was endemic to the island of Cuba in the Caribbean. The remains were found in Pleistocene deposits in Pinar del Rio. Probably derived from an early invasion of sandhill cranes from North America, it differed from that species by, as well as larger size, having a proportionately broader bill, stockier legs, and with reduced wings and pectoral girdle indicating that it may have been flightless. Currently, the only extant Caribbean crane is the Cuban sandhill crane, "Antigone