Moa are described as tall(up to six ft for female south island moa, not counting head and neck), three-toed, with long necks and no wings to speak of. Skeletons indicate they held their head horizontal to their body. Rings that support their trachea indicate that some may have had a deep resonating call.
Many Moa skeletons, especially Dinornis, of which there are two(formerly three,) species. The difference as such that they were classified as different species, D.struthioides and D. Robustus. DNA tests, however, have proven D.Robustus to be the female and struthioides, male. Now both are classified as D.robustus or South Island Moa, which have separated into three distinct lineages. The other species is D.novaezealandiae or South Island Moa.
DNA also indicates that Euryapteryx curtus and Euryapteryx gravis are the same, both being the broad-billed moa. The size difference is due to them being a subspecies and not sexual dimorphism.
Other than sexual dimorphism we also know that Moa lay few eggs. They took a long time to mature, growth rings indicating they took up to ten years to reach maturity. Nest discoveries indicate moa nested in caves, scratching a depression in the dirt, then built a platform of flora. Coprolites containing seeds indicate moa nested in late spring to summer. All but the Upland moa lay white eggs, Upland Moa eggs were blue-green. Suprisingly, the larger moa had thinner eggshells.
There were Moa for all New Zealand environments, as long as they held enough plant life to support these herbivores.
During their time, adult moa had few predators. The only known one being the Haast's eagle. Until the Maori came. The Maori are people who arrived in New Zealand between 1250 and 1300 CE. In what appears to be less than a hundred years, the Moa were gone.
There have been eyewitness accounts of moa sightings to this day.
(pic is an upland moa)
There was actually more species of this bird, even a smaller Moa called the Little Bush Moa as well as the larger ones..and some even claim that the Kiwi was a species of them to, but science would beg to differ..
Little Bush Moa
And this is the only real intact mummified remains of a Preserved foot of a Moa (Megalapteryx didinus) found near Queenstown in 1878 - The foot is currently held by the Natural History Museum, London. There were 11 species of these flightless birds endemic to New Zealand, ranging from 40 to 600 pounds. Early Maori settlement sites are littered with moa bones suggesting they were an important food of the first New Zealand Maori peoples from Polynesia.