These birds belong to the order Dinornithiformes, which is confined to New Zealand. Like kiwis they are very ancient birds of uncertain relationship. Their earliest fossils date from the upper Miocene era – approximately 15 million years ago – but their origin is certainly much earlier. Together with the elephant birds of Madagascar, they comprise some of the largest of all birds though some species were of moderate size. Moas were flightless Ratite birds (that is, with no keel to the raft-shaped breastbone or sternum), and are now extinct. Two families, six genera, and about 25 species are recognised. They occurred in North, South, and Stewart Islands, with South Island supporting the most species, about 19, and with Stewart Island the least, two. The process of extinction of moas was probably greatly accelerated following the arrival of man in New Zealand before A.D. 1000. The earliest Polynesian inhabitants, the moa hunters, used moas for food, their bones for implements and ornaments; the eggs were used for water bottles. Giant moas were probably extinct about A.D. 1500; the smaller bush moas may have lingered on in remote parts of the South Island until the early nineteenth century.
Moas had massive skeletons with small, broad, flattened skulls, short bills, and no wings. Their feathers were similar to those of the emu. The largest egg known is about 10 by 7 in. In New Zealand moas took the place of absent grazing and browsing mammals, and apparently fed mainly on grass, leaves, and fruits. In some places deposits of gizzard stones of white quartz have been discovered. Bones are found mainly in swamps and caves, the first being discovered in the early 1830s.
by Gordon Roy Williams, B.SC.(HONS.)(SYDNEY), Lecturer in Agricultural Zoology, Lincoln Agricultural College.