Moas are an extinct species belonging to the flightless family of birds known as Ratites. Living members of this family are, Kiwi, Emu, Ostrich, Rhea & Cassowary. The word ratite comes from the Latin ratis (raft) and refers to the flat, raft-like breast bone that all ratites possess.
Moas are the only wingless bird known. Other flightless birds such as Kiwi and Emu have reduced wings. They would have had a ‘shaggy’ appearance due to their feathers' loose construction, typical of the feathers of ratites. It is thought there were up to 13 species of Moa, ranging from the size of a turkey, at about 12-15 kg, through to the Giant Moa (dinornis giganteus) that is estimated to have weighed about 270 kg and stood up to 3 metres tall.
Physiological differences between species show they existed in a range of habitats, from open grasslands to dense bush. Before humans arrived, the only predator capable of killing adult Moas was the New Zealand Eagle (harpigornis).
Moa were thought to have become extinct due to over exploitation, in the form of hunting, and habitat destruction, caused by early Maori. Species such as the domestic dog and the Kiore (rattus exulans) the south-east Asian rat, introduced to New Zealand by Maori, may have also contributed to their demise.