Slightly smaller than the South Island giant moa, the North Island species was the second tallest of the nine moa species, standing up to 2 metres at the back and up to 3 metres with neck stretched upwards. Both giant moa species (genus Dinornis) had relatively long, shaggy hair-like feathers up to 18 cm long, covering the body, and exhibited the greatest size difference between males and females of any bird, with adult females being much larger than adult males. Size also varied by habitat,  with lowland populations in mosaic shrubland larger than upland populations in closed forest. DNA study suggests that moa were more closely related to the flighted South American tinamou than to the kiwi.

Identification                                                                                       

The North Island giant moa was a very tall, relatively slender moa with a relatively small, broad, flattened head, and robust, flattened, slightly decurved bill. Females were markedly larger than males, being c.150% taller and c.280% heavier.

Similar species: the North Island giant moa was much taller and more gracile than the stout-legged moa, which was the only other large moa species in the North Island

Distribution and habitat

The North Island giant moa occupied a wide range of vegetated habitats from coastal dunes to inland shrublands, forests, and subalpine herbfields and grasslands in the North Island and Aotea/Great Barrier Island. Bone remains show that it was widespread in forest and shrubland areas on the coast and adjacent hinterland from North Cape to Wellington.

Population

The North Island giant moa was widespread and abundant. Its bones are common in archaeological sites.

Threats and conservation

The main cause of extinction was overhunting by humans for food. Moa chicks may have also been eaten by the introduced Polynesian dog (kuri).

Breeding

The remains of a large white moa egg (190 x 150 mm) thought to be from this species was found in a rock shelter near Waitomo. It is estimated that this egg would have weighed over 3 kg when fresh.

Behaviour and ecology

The relatively long leg bones of giant moa indicates that they were more agile than other large moa species, and a large olfactory lobe suggests that they had an acute sense of smell.

Food

Based on their skull and bill morphology and the frequent presence of large masses of gizzard stones, it is likely that North Island moa consumed a fibrous diet of twigs and leaves. Flowers, berries and seeds from trees, shrubs and vines were also taken, but they consumed few herbs or grasses.

Weblinks

Wikipedia

References

Anderson, A. 1989. Prodigious birds: moas and moa-hunting in prehistoric New Zealand. Cambridge University Press, Cambridge, UK.

Baker, A. J.; Haddrath, O.; McPherson, J. D.; and Cloutier, A. 2014. Genomic support for a moa-tinamou clade and adaptive morphological convergence in flightless ratites. Molecular Biology and Evolution, Vol 31, Issue 7: 1686-1696.

Bunce, M.; Worthy, T.H.; Phillips, M.J.; Holdaway, R.N.; Willersley, E.; Haile, J.; Shapiro, B.; Scofield, R.P.; Drummond, A.; Kamp, P.J.J.; Cooper, A. 2009. The evolutionary history of the extinct ratite moa and New Zealand neogene paleogeography. Proceedings of the National Academy of Sciences USA 106: 20646-20651.

Gill, B.J. 2007. Eggshell characteristics of moa eggs (Aves: Dinornithiformes). Journal of the Royal Society of New Zealand 37: 139-150.

Gill, B.; Martinson, P. 1991. New Zealand's extinct birds. Random Century, New Zealand.

Huynen, L.; Gill, B.J.; Millar, C.D.; Lambert, D.M. 2010. Ancient DNA reveals extreme egg morphology and nesting behavior in New Zealand’s extinct moa. Proceedings of the National Academy of Sciences (PNAS) 107: 16201-16206.

Phillips, M.J.; Gibb, G.C.; Crimp, E.A.; Penny, D. 2010. Tinamous and moa flock together: mitochondrial genome sequence analysis reveals independent losses of flight among ratites. Systematic Biology 59: 90-107.

Rawlence, N.J.; Wood, J.R.; Armstrong, K.N.; Cooper, A. 2009. DNA content and distribution in ancient feathers and potential to reconstruct the plumage of extinct avian taxa. Proceedings of the Royal Society. B 7 (1672): 3395-3402.

Szabo, M. 2005. Hobbit-sized raptor became 'Lord of the Wings'. Forest & Bird, May 2005, Issue 316: 12.

Szabo, M. 2006. Extinct birds of New Zealand: a preview. Forest & Bird, November 2006, Issue 322: 22-24.

Tennyson, A.; Martinson, P. 2006. Extinct birds of New Zealand. Te Papa Press, Wellington.

Tennyson, A.J.D. 2010. Dinornithiformes. Pp. 11-18. In: Checklist Committee (OSNZ) Checklist of the birds of New Zealand, Norfolk and Macquarie Islands, and the Ross Dependency, Antarctica (4th ed.). Ornithological Society of New Zealand & Te Papa Press, Wellington.

Wood, J.R. 2008. Moa (Aves: Dinornithiformes) nesting material from rockshelters in the semi-arid interior of South Island, New Zealand. Journal of the Royal Society of New Zealand 38: 115-129.

Wood, J.R.; Wilmshurst, J.M.; Wagstaff, S.J.; Worthy, T.H.; Rawlence, N.J.; Cooper, A. 2012. High-resolution coproecology: using coprolites to reconstruct the habits and habitats of New Zealand’s extinct upland moa (Megalapteryx didinus). PLoS ONE 7: e40025.

Worthy, T.H.; Holdaway, R.N. 2002. The lost world of the moa: prehistoric life in New Zealand. Canterbury University Press, Christchurch.

Worthy, T.H.; Scofield, R.P. 2012. Twenty-first century advances in knowledge of the biology of moa (Aves: Dinornithiformes): a morphological analysis and diagnosis revised. New Zealand Journal of Zoology 39: 87-153.

Recommended citation

Szabo, M.J. 2013 [updated 2022]. North Island giant moa | kuranui. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz