This would have allowed them to graze on low-elevation vegetation, while being able to lift their heads and browse trees when necessary.
This has resulted in a reconsideration of the height of larger moa.
Moa fed on a range of plant species and plant parts, including fibrous twigs and leaves taken from low trees and shrubs. They are characterised by having low fecundity and a long maturation period, taking approximately ten years to reach adult size.
The beak of Pachyornis elephantopus was analogous to a pair of secateurs, and was able to clip the fibrous leaves of New Zealand flax (Phormium tenax) and twigs up to at least 8 mm in diameter. The large Dinornis species took the same length of time to reach adult size as small moa species, and as a result had an accelerated rate of skeletal growth during their juvenile years.
Moa extinction occurred around 1300 Although moa skeletons were traditionally reconstructed in an upright position to create impressive height, analysis of their vertebral articulation indicates that they probably carried their heads forward, in the manner of a kiwi.
The spine was attached to the rear of the head rather than the base, indicating the horizontal alignment.
The nine species of moa were the only wingless birds lacking even the vestigial wings which all other ratites have.
They were the dominant herbivores in New Zealand's forest, shrubland and subalpine ecosystems for thousands of years, and until the arrival of the Māori were hunted only by the Haast's eagle.
Dinornis seems to have had the most pronounced sexual dimorphism, with females being up to 150% as tall and 280% as heavy as males—so much bigger that they were formerly classified as separate species until 2003.
Their distributions in coastal areas have been rather unclear, but were present at least in several locations such as on Kaikoura, Otago Peninsula, Although the South Island and the North Island shared some moa species (Euryapteryx gravis, Anomalopteryx didiformis), most were exclusive to one island, reflecting divergence over several thousand years since lower sea level had resulted in a land bridge across Cook Strait.
In the North Island, Dinornis novaezealandiae and Anomalopteryx didiformis dominated in high rainfall forest habitat; a similar pattern to the South Island.
Size differences can be explained by a north-south cline combined with temporal variation such that specimens were larger during the Otiran glacial period (the last ice age in New Zealand).
Similar temporal size variation is known for the North Island Pachyornis mappini.
Excavation of these rings from articulated skeletons has shown that at least two moa genera (Euryapteryx and Emeus) exhibited tracheal elongation, that is, their trachea were up to 1 metre (3 ft) long and formed a large loop within the body cavity.