Recently Extinct Animals - The Extinct Moa Birds of New Zealand

Giant, flightless bird species, collectively called moa roamed New Zealand’s forests. In New Zealand, they filled the niche for browsing mammals that could be found in the rest of the world. For more than 2 million years these birds were the dominant species in New Zealand occupying the habitats from sea level to sub alpine herb fields.

The several species of moa had to fear only the Haast Eagle, Harpagornis moorei, prior to the coming of humans. This bird of prey was the largest eagle that ever lived.

Image: Giant Haast's eagle attacking New Zealand moa. Created by John Megahan. Copyright PLoS Biology. This image has been released under the Creative Commons Attribution ShareAlike 2.5 Licence.

Despite traces of an earlier human contact, the first Polynesian settlement of New Zealand appears to have begun in earnest during the late 13^th century. These Polynesians were the ancestors of modern Maoris. These people hunted the moas severely, which caused a decline in moa populations. Moas, like any other long-lived birds, were highly vulnerable to human predation. Other factors that caused the moa populations to decline were a human population increase and habitat loss through forest clearance by the early settlers. The moa disappeared from the Maori’s menu after 50-160 years, and within 200 years of human settlement the several moa species became extinct and forgotten.

The earliest evidence of moa bones in New Zealand found in 1834 by a trader named Joel Polack when he was shown "several large fossil ossifications" by the Maori. He concluded that it had to be a species of emu, or a bird of the genus Struthio that had once lived in New Zealand. His conclusion was published in a book that escaped the attention o scientists of the day. Polack did not keep the bones and the giant birds of New Zealand remained unknown for a few more years.

Trader John W. Harris acquired the shaft of a femur somewhere between 1831 and 1836 from the East Coast of the North Island of New Zealand. Dr. John Rule was given this bone in 1837 by his friend Harris. In 1839, Rule took the bone to England and compared it with various animal bones. He convinced himself it was from a bird. Rule tried to sell it to the British Museum and was declined. Next, under the advise of G.R. Gray, he approached the Royal College of Surgeons, who forwarded the bone and a letter from Rule outlining his believe that it was from a bird, to Professor Richard Owen for appraisal. Owen also compared it with various animal and human bones and came also to the conclusion it was from a bird. The bone was then sold to Mr. M.P. Bright from Bristol, and only many years later it was acquired by the British Museum. From this bone Owen concluded in 1940 that there has existed, or still existed, a Struthious bird nearly if not quite equal in size to the Ostrich in New Zealand. Soon more moa bones were discovered and Owen erected in 1943 the genus Dinornis to accommodate the bones from New Zealand. Dinornis (Greek) can be variously interpreted as "surprising," "prodigious," or "terrible" birds.

Photo: Sir Richard Owen and Dinornis skeleton from The Book of Knowledge, The Grolier Society, 1911. This image is in the public domain because its copyright has expired. This applies to the European Union, Canada, the United States and those countries with a copyright term of life of the author plus 70 years.

The first substantial collection of moa bones to reach England was acquired by the missionary Reverend W. Williams from streams near Poverty Bay, Wairoa, between 1839 and 1842. He sent them to the geologist Dr. W. Buckland at Oxford. In an accompanying letter dated February 18, 1842, Williams stated that the bones came from birds known to the Maori as "moa".

But even though finds of moa bones are now relatively abundant, it has been difficult to build a complete picture of these animals. The first 150 years of taxonomic and systematic studies resulted in a proliferation of names (at least 64 species and 20 genera) being applied to moa. This was only for the trend to go into reverse, mainly because samples that were thought to represent separate species turned out, in fact to be from males and females of the same species. Rothschild accepted 37 species, Archey 20 and Oliver 29. The gender hassle has meant that the number of recognised moa species has plummeted to only 11 when finally consensus was reached.

These 11 moa species from the order Dinornithiformes (Moas) could be divided into two families and were:

Family:	Emeidae (Emeid Moas)
Subfamily:	Anomalopteryginae
Species:	Anomalopteryx didiformes Owen, 1844	Little Bush Moa
	Megalapteryx didinus (Owen, 1883)	Upland Moa
	Pachyornis australis Oliver, 1949	Crested Moa
	Pachyornis elephantopus (Owen,1856)	Heavy-footed Moa
	Pachyornis mappini Archey, 1941	Mappin’s Moa
Subfamily:	Emeinae
Species:	Emeus crassus (Owen, 1846)	Eastern Moa
	Euryapteryx curtus (Owen, 1846)	Coastal Moa
	Euryapteryx geranoides (Owen, 1848)	Stout-legged Moa

Family:	Dinornithidae (Dinornithid Moas)
Species:	Dinornis giganteus Owen, 1844	Giant Moa
	Dinornis novaezealandiae Owen, 1843	Large Bush Moa
	Dinornis struthoides Owen, 1844	Slender Bush Moa

Two teams of scientists in New Zealand and Britain believe to have sorted out the gender problem in moa species, carrying out what they call the first “molecular sexing” of an extinct species. They have done this by sifting through tiny scraps of DNA teased out of old moa bones. By looking at mitochondrial DNA, the part of a cell that is descended from the maternal line, they found that, in fact, there were only two genetically distinct species of Dinornithid Moa. One was on New Zealand’s North Island, and the other on the South Island, with the waters of the Cook Strait providing an impenetrable barrier to a flightless bird. The original designation of three species of the genus Dinornis was based on the assumption that the level of size difference detected in the genus is too large to represent a single species.

Emeus crassus (Owen, 1846) in the National Museum of Natural History Naturalis in Leiden, the Netherlands. Photographed by Peter Maas in 2002.

Reassembling the bones and the species, the researchers show that there was an incredible difference in size between males and females. Females were nearly three times heavier and stood half as tall against their males, a difference that is unprecedented among birds and terrestrial mammals. The detailed mitochondrial DNA analyses of the moa fossils show that all the remains from Dinornis struthoides, the smallest Dinornithid moa, came from males and that the other remains, from Dinornis novaezealandiae and Dinornis giganteus, came from females. The disparity between small and large females probably stemmed from diet. Dinornis novaezealandiae was smaller than the largest moa ever, the Dinornis giganteus. The disparity between small and large females probably stemmed from diet. Dinornis novaezealandiae occurred in ecosystems that weren’t as biological productive, and thus didn’t provide as much nutrition as those where Dinornis giganteus occurred. Females in related species such as the kiwi and the cassowary are also the bigger gender. Both the scientists from the Lambert-Millar group and the other group led by Oxford-based expatriate New Zealander Dr. Alan Cooper found that females accounted for the most moa bones that have been preserved in swamps and deposited in museums. That suggests the females were out foraging and maybe the males were sitting on the eggs, as the male kiwi does. Dr Cooper’s group suggested that the big females were needed to produce big eggs for their young to survive in the forests.

Family:	Dinornithidae (Dinornithid Moas)
Species:	Dinornis novaezealandiae Owen, 1843	North Island Bush Moa, North Island Giant Moa
Species:	Dinornis robustus Owen, 1846	South Island Bush Moa, South Island Giant Moa

The species Dinornis giganteus and Dinornis struthoides are now placed in the synonymy of Dinornis novaezealandiae. Leaving only a total of 10 moa species that have lived in historic times on this planet.

However, five additional species of moa have recently been identified by evolutionary biologists. The researchers, led by Professor David Lambert, say they now have evidence that increases the number of known moa species from 10 to 14. Their paper on reconstructing the tempo and model of evolution with the extinct giant moas has featured in June 2005 in one of the world’s top scientific journals, Proceedings of the National Academy of Sciences USA. They have been able to genetically type samples of ancient DNA extracted from 125 moa bones. The research provides overwhelming evidence to show the existence of more species. According to their research there would possibly just one Euryapteryx species, two more Pachyornis species and two more Dinornis species. They also question the recent synonymy of Megalapteryx benhami Archey, 1941. Their research shows that there were most likely two species of Megalapteryx, namely Megalapteryx didinus and possibly Megalapteryx benhami.