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This article is about the extinct New Zealand birds known as moa. For other uses, see Moa (disambiguation).

Moa
Temporal range: Miocene – Holocene, 17–0.0006 Ma
North Island giant moa skeleton
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Infraclass: Palaeognathae
Clade: Notopalaeognathae
Clade: Dinocrypturi
Order: †Dinornithiformes
Bonaparte, 1853[1]
Type species
†Dinornis novaezealandiae
Owen, 1843
Subgroups

See text

Diversity[2]
6 genera, 9 species
Synonyms[3]
  • Dinornithes Gadow, 1893
  • Immanes Newton, 1884

Moa[note 1] (order Dinornithiformes) are an extinct group of flightless birds formerly endemic to New Zealand.[4][note 2] During the Late Pleistocene-Holocene, there were nine species (in six genera). The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about 3.6 metres (12 ft) in height with neck outstretched, and weighed about 230 kilograms (510 lb)[5] while the smallest, the bush moa (Anomalopteryx didiformis), was around the size of a turkey.[6] Estimates of the moa population when Polynesians settled New Zealand circa 1300 vary between 58,000[7] and approximately 2.5 million.[8]

Moa are traditionally placed in the ratite group.[4] Genetic studies have found that their closest relatives are the flighted South American tinamous, once considered a sister group to ratites.[9] The nine species of moa were the only wingless birds, lacking even the vestigial wings that all other ratites have. They were the largest terrestrial animals and dominant herbivores in New Zealand's forest, shrubland, and subalpine ecosystems until the arrival of the Māori, and were hunted only by Haast's eagle. Moa extinction occurred within 100 years of human settlement of New Zealand, primarily due to overhunting.[7]

Etymology

[edit]

The word moa is a Polynesian term for domestic fowl. The name was not in common use among the Māori by the time of European contact, likely because the bird it described had been extinct for some time. Nevertheless, knowledge was passed down through traditional stories and proverbs, such as kua ngaro i te ngaro o te moa (lost as the moa is lost).[10] The earliest written record of the name was by missionaries William Williams and William Colenso in January 1838; Colenso speculated that the birds may have resembled gigantic fowl.[citation needed] In 1912, Māori chief Urupeni Pūhara claimed that the moa's traditional name was "te kura" (the red bird).[11] The North Island giant moa is also called kuranui.

Description

[edit]
Size comparison between four moa species and a 1.8 m tall human. From left to right: Megalapteryx didinus, Dinornis robustus (female size), Anomalopteryx didiformis, and Pachyornis elephantopus

Moa skeletons were traditionally reconstructed in an upright position to create impressive height, but analysis of their vertebral articulations indicates that they probably carried their heads forward,[12] in the manner of a kiwi. The spine was attached to the rear of the head rather than the base, indicating the horizontal alignment. This would have let them graze on low 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. However, Māori rock art depicts moa or moa-like birds with necks upright, indicating that moa were capable of assuming both neck postures.[13][14]

No records survive of what sounds moa made, though some idea of their calls can be gained from fossil evidence. The trachea of moa were supported by many small rings of bone known as tracheal rings. These rings were preserved within some articulated skeletons, and shows that at least two moa genera (Euryapteryx and Emeus) exhibited tracheal elongation, where their trachea, up to 1 metre (3.3 feet) long, formed a large loop within the body cavity.[12] They are the only ratites known to exhibit this feature, which is also present in several other bird groups, including swans, cranes, and guinea fowl. The feature is associated with deep resonant vocalisations that can travel long distances.

Feathers and soft tissues

[edit]

Several examples of moa remains have been found with soft tissues (muscle, skin, feathers) preserved through desiccation after the bird died at a dry site (for example, a cave with a constant dry breeze blowing through it); these specimens are a form of natural mummy. Most were found in the semiarid Central Otago region, the driest part of New Zealand, but others are known from outside the Central Otago region. These include:

Neck tissue of Emeus crassus
Holotype head and neck of Megalapteryx
Soft tissue attached of several moas
Megalapteryx desiccated head
Megalapteryx holotype foot
  • Dried muscle on bones of a female Dinornis robustus found at Tiger Hill in the Manuherikia River Valley by gold miners in 1864[15] (currently held by Yorkshire Museum)
  • Several bones of Emeus crassus with muscle attached, and a row of neck vertebrae with muscle, skin, and feathers collected from Earnscleugh Cave near the town of Alexandra in 1870[16] (currently held by the Otago Museum)
  • An articulated foot of a male D. giganteus with skin and foot pads preserved, found in a crevice on the Knobby Range in 1874[17] (currently held by the Otago Museum)
  • The type specimen of Megalapteryx didinus found near Queenstown in 1878[15] (currently held by Natural History Museum, London; see photograph of foot on this page)
  • The lower leg of Pachyornis elephantopus, with skin and muscle, from the Hector Range in 1884;[18][17] (currently held by the Zoology Department, Cambridge University)
  • The complete feathered leg of a M. didinus from Old Man Range in 1894[19] (currently held by the Otago Museum)
  • The head of a M. didinus found near Cromwell sometime before 1949[20] (currently held by Te Papa Tongarewa).
  • A complete foot of M. didinus found in a cave on Mount Owen near Nelson in the 1980s[21] (currently held by Te Papa Tongarewa)
  • A skeleton of Anomalopteryx didiformis with muscle, skin, and feather bases collected from a cave near Te Anau in 1980.[22]
Preserved feathers of Megalapteryx

In addition to these specimens, loose moa feathers have been collected from caves and rock shelters in the southern South Island, and based on these remains, some idea of the moa plumage has been achieved. The preserved leg of M. didinus from the Old Man Range reveals that this species was feathered right down to the foot. This is likely to have been an adaptation to living in high-altitude, snowy environments, and is also seen in the Darwin's rhea, which lives in a similar seasonally snowy habitat.[12]

Moa feathers are up to 23 cm (9 in) long, and a range of colours has been reported, including reddish-brown, white, yellowish, and purplish.[12] Dark feathers with white or creamy tips have also been found, and indicate that some moa species may have had plumage with a speckled appearance.[23]

Classification

[edit]

Evolutionary relationships

[edit]
A comparison of a kiwi (l), ostrich (c), and Dinornis (r), each with its egg
Restoration of a broad-billed moa

The moa's closest relatives are small terrestrial South American birds called the tinamous, which can fly.[9][24][25][26] Previously, the kiwi, the Australian emu, and cassowary[27] were thought to be most closely related to moa.

Although dozens of species were described in the late 19th and early 20th centuries, many were based on partial skeletons and turned out to be synonyms. Currently, 11 species are formally recognised, although recent studies using ancient DNA recovered from bones in museum collections suggest that distinct lineages exist within some of these. One factor that has caused much confusion in moa taxonomy is the intraspecific variation of bone sizes, between glacial and interglacial periods (see Bergmann's rule and Allen's rule), as well as sexual dimorphism being evident in several species. 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 classified as separate species until 2003.[28][29] A 2009 study showed that Euryapteryx curtus and E. gravis were synonyms.[30] A 2010 study explained size differences among them as sexual dimorphism.[31] A 2012 morphological study interpreted them as subspecies, instead.[32]

Analyses of ancient DNA have determined that a number of cryptic evolutionary lineages occurred in several moa genera.[33] These may eventually be classified as species or subspecies; Megalapteryx benhami (Archey) is synonymised with M. didinus (Owen) because the bones of both share all essential characters. 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's Pachyornis mappini.[34] Some of the other size variation for moa species can probably be explained by similar geographic and temporal factors.[35]

The earliest moa remains come from the Miocene Saint Bathans Fauna. Known from multiple eggshells and hind limb elements, these represent at least two already fairly large-sized species.[36]

Phylogeny

[edit]
The skeletons of an eastern moa (l), ostrich (rear), and Fiordland penguin (r) in the Otago Museum

Because moa are a group of flightless birds with no vestiges of wing bones, questions have been raised about how they arrived in New Zealand, and from where. Many theories exist about the moa's arrival and radiation in New Zealand, but the most recent theory suggests that they arrived in New Zealand about 60 million years ago (Mya) and split from the "basal" (see below) moa species, Megalapteryx, about 5.8 Mya[37] instead of the 18.5 Mya split suggested by Baker et al. (2005). This does not necessarily mean there was no speciation between the arrival 60 Mya and the basal split 5.8 Mya, but the fossil record is lacking and most likely the early moa lineages existed, but became extinct before the basal split 5.8 Mya.[38] The presence of Miocene-aged species certainly suggests that moa diversification began before the split between Megalapteryx and the other taxa.[36]

The Oligocene Drowning Maximum event, which occurred about 22 Mya, when only 18% of present-day New Zealand was above sea level, is very important in the moa radiation. Because the basal moa split occurred so recently (5.8 Mya), it was argued that ancestors of the Quaternary moa lineages could not have been present on both the South and North Island remnants during the Oligocene drowning.[39] This does not imply that moa were previously absent from the North Island, but that only those from the South Island survived, because only the South Island was above sea level. Bunce et al. (2009) argued that moa ancestors survived on the South Island and then recolonised the North Island about 2 Myr later, when the two islands rejoined after 30 Myr of separation.[29] The presence of Miocene moa in the Saint Bathans fauna seems to suggest that these birds increased in size soon after the Oligocene drowning event, if they were affected by it at all.[36]

Bunce et al. also concluded that the highly complex structure of the moa lineage was caused by the formation of the Southern Alps about 6 Mya, and the habitat fragmentation on both islands resulting from Pleistocene glacial cycles, volcanism, and landscape changes.[29] The cladogram below is a phylogeny of Palaeognathae generated by Mitchell (2014)[25] with some clade names after Yuri et al. (2013).[40] It provides the position of the moa (Dinornithiformes) within the larger context of the "ancient jawed" (Palaeognathae) birds:

Palaeognathae

The cladogram below gives a more detailed, species-level phylogeny, of the moa branch (Dinornithiformes) of the "ancient jawed" birds (Palaeognathae) shown above:[29]

†Dinornithiformes

Taxonomy

[edit]

The currently recognised genera and species are:[5]

Two unnamed species are also known from the Saint Bathans Fauna.[36]

Skeletons (not to scale)
Anomalopteryx didiformis
Pachyornis elephantopus
Pachyornis geranoides
Megalapteryx didinus
Dinornis robustus

Distribution and habitat

[edit]

Analyses of fossil moa bone assemblages have provided detailed data on the habitat preferences of individual moa species, and revealed distinctive regional moa faunas:[12][41][42][43][44][45][46]

South Island

[edit]
A restoration of Dinornis robustus and Pachyornis elephantopus, both from the South Island

The two main faunas identified in the South Island include:

The fauna of the high-rainfall west coast beech (Nothofagus) forests that included Anomalopteryx didiformis (bush moa) and Dinornis robustus (South Island giant moa), and
The fauna of the dry rainshadow forest and shrublands east of the Southern Alps that included Pachyornis elephantopus (heavy-footed moa), Euryapteryx curtus, Emeus crassus, and Dinornis robustus.

A 'subalpine fauna' might include the widespread D. robustus, and the two other moa species that existed in the South Island:

Pachyornis australis, the rarest moa species, the only moa species not yet found in Māori middens. Its bones have been found in caves in the northwest Nelson and Karamea districts (such as Honeycomb Hill Cave), and some sites around the Wānaka district.
Megalapteryx didinus, more widespread, named "upland moa" because its bones are commonly found in the subalpine zone. However, it also occurred down to sea level, where suitable steep and rocky terrain (such as Punakaiki on the west coast and Central Otago) existed. Their distributions in coastal areas have been rather unclear, but were present at least in several locations such as on Kaikōura, Otago Peninsula,[47] and Karitane.[48]

North Island

[edit]

Significantly less is known about North Island paleofaunas, due to the scarcity of fossil sites compared to the South Island, but the basic pattern of moa-habitat relationships was the same.[12] The South Island and the North Island shared some moa species (Euryapteryx curtus, Anomalopteryx didiformis), but most were exclusive to one island, reflecting divergence over several thousand years since lower sea level in the Ice Age had made a land bridge across the Cook Strait.[12]

In the North Island, Dinornis novaezealandiae and Anomalopteryx didiformis dominated in high-rainfall forest habitat, a similar pattern to the South Island. The other moa species present in the North Island (Euryapteryx curtus, and Pachyornis geranoides) tended to inhabit drier forest and shrubland habitats. P. geranoides occurred throughout the North Island.[12]

Behaviour and ecology

[edit]
Preserved footprints of a D. novaezealandiae found in 1911

About eight moa trackways, with fossilised moa footprint impressions in fluvial silts, have been found in the North Island, including Waikanae Creek (1872), Napier (1887), Manawatū River (1895), Marton (1896), Palmerston North (1911) (see photograph to left), Rangitīkei River (1939), and under water in Lake Taupō (1973). Analysis of the spacing of these tracks indicates walking speeds between 3 and 5 km/h (1.9 and 3.1 mph).[12] In 2022, an additional trackway was discovered at the entrance of Kaipara Harbour.[49]

In 2019, the first known trackway in the South Island was found in a riverbed at Kyeburn, Otago.[50] A second set of footprints were discovered at Pareora, Canterbury, in 2022.[51]

Studies of accumulated dried vegetation in the pre-human mid-late Holocene period suggests a low Sophora microphylla or Kōwai forest ecosystem in Central Otago that was used by — and perhaps maintained by — moa for both nesting material and food. By the 1850s, when European settlers came to the area, neither the forests nor moa were present, vanishing prior to settlement by colonists.[52]

Diet

[edit]

Their diet has been deduced from fossilised contents of their gizzards[53][54] and coprolites,[55] as well as indirectly through morphological analysis of skull and beak, and stable isotope analysis of their bones.[12] Moa fed on a range of plant species and plant parts, including fibrous twigs and leaves taken from low trees and shrubs. The beak of Pachyornis elephantopus was analogous to a pair of secateurs, and could clip the fibrous leaves of New Zealand flax (Phormium tenax) and twigs up to at least 8 mm in diameter.[54]

Moa filled the ecological niche occupied in other countries by large browsing mammals such as antelope and llamas.[56] Some biologists contend that a number of plant species evolved to avoid moa browsing.[56] Divaricating plants such as Pennantia corymbosa (the kaikōmako), which have small leaves and a dense mesh of branches, and Pseudopanax crassifolius (the horoeka or lancewood), which has tough juvenile leaves, are possible examples of plants that evolved in such a way. Likewise, it has been suggested that heteroblasty might be a response to moa browsing.[57]

Like many other birds, moa swallowed gizzard stones (gastroliths), which were retained in their muscular gizzards, providing a grinding action that allowed them to eat coarse plant material. This grinding action suggests that moa were not effective seed dispersers, with only the smallest seeds passing through their gut intact.[58] These stones were commonly smooth rounded quartz pebbles, but stones over 110 millimetres (4 in) long have been found among preserved moa gizzard contents.[54] Dinornis gizzards could often contain several kilograms of stones.[12] Moa likely exercised a certain selectivity in the choice of gizzard stones and chose the hardest pebbles.[59]

Reproduction

[edit]
An egg and embryo fragments of Emeus crassus

The pairs of species of moa described as Euryapteryx curtus / E. exilis, Emeus huttonii / E. crassus, and Pachyornis septentrionalis / P. mappini have long been suggested to constitute males and females, respectively. This has been confirmed by analysis for sex-specific genetic markers of DNA extracted from bone material.[28]

For example, before 2003, three species of Dinornis were recognised: South Island giant moa (D. robustus), North Island giant moa (D. novaezealandiae), and slender moa (D. struthioides). However, DNA showed that all D. struthioides were males, and all D. robustus were females. Therefore, the three species of Dinornis were reclassified as two species, one each formerly occurring on New Zealand's North Island (D. novaezealandiae) and South Island (D. robustus);[28][60] D. robustus however, comprises three distinct genetic lineages and may eventually be classified as many species, as discussed above.

Examination of growth rings in moa cortical bone has revealed that these birds were K-selected, as are many other large endemic New Zealand birds.[27] They are characterised by having a low fecundity and a long maturation period, taking about 10 years to reach adult size. The large Dinornis species took as long to reach adult size as small moa species, and as a result, had fast skeletal growth during their juvenile years.[27]

Model of a juvenile Coastal Moa (Euryapteryx curtus)

No evidence has been found to suggest that moa were colonial nesters. Moa nesting is often inferred from accumulations of eggshell fragments in caves and rock shelters, little evidence exists of the nests themselves. Excavations of rock shelters in the eastern North Island during the 1940s found moa nests, which were described as "small depressions obviously scratched out in the soft dry pumice".[61] Moa nesting material has also been recovered from rock shelters in the Central Otago region of the South Island, where the dry climate has preserved plant material used to build the nesting platform (including twigs clipped by moa bills).[62] Seeds and pollen within moa coprolites found among the nesting material provide evidence that the nesting season was late spring to summer.[62]

Fragments of moa eggshell are often found in archaeological sites and sand dunes around the New Zealand coast. Thirty-six whole moa eggs exist in museum collections and vary greatly in size (from 120–240 millimetres (4.7–9.4 in) in length and 91–178 millimetres (3.6–7.0 in) wide).[63] The outer surface of moa eggshell is characterised by small, slit-shaped pores. The eggs of most moa species were white, although those of the upland moa (Megalapteryx didinus) were blue-green.[64]

The skeleton of female upland moa with egg in unlaid position within the pelvic cavity in Otago Museum

A 2010 study by Huynen et al. found that the eggs of certain species were fragile, only around a millimetre in shell thickness: "Unexpectedly, several thin-shelled eggs were also shown to belong to the heaviest moa of the genera Dinornis, Euryapteryx, and Emeus, making these, to our knowledge, the most fragile of all avian eggs measured to date. Moreover, sex-specific DNA recovered from the outer surfaces of eggshells belonging to species of Dinornis and Euryapteryx suggest that these very thin eggs were likely to have been incubated by the lighter males. The thin nature of the eggshells of these larger species of moa, even if incubated by the male, suggests that egg breakage in these species would have been common if the typical contact method of avian egg incubation was used."[64] Despite the bird's extinction, the high yield of DNA available from recovered fossilised eggs has allowed the moa's genome to be sequenced.[65]

Relationship with humans

[edit]

Discovery

[edit]
Haast's eagle attacking a moa pair

Before the arrival of humans, the moa's only predator was the massive Haast's eagle. New Zealand had been isolated for 80 million years and had few predators before human arrival, meaning that not only were its ecosystems extremely vulnerable to perturbation by outside species, but also the native species were ill-equipped to cope with human predators.[66][67] Polynesians arrived sometime before 1300, and all moa genera were soon driven to extinction by hunting and, to a lesser extent, by habitat reduction due to forest clearance. By 1445, all moa had become extinct, along with Haast's eagle, which had relied on them for food. Recent research using carbon-14 dating of middens strongly suggests that the events leading to extinction took less than a hundred years,[68] rather than a period of exploitation lasting several hundred years as previously hypothesised.

An expedition in the 1850s under Lieutenant A. Impey reported two emu-like birds on a hillside in the South Island; an 1861 story from the Nelson Examiner told of three-toed footprints measuring 36 cm (14 in) between Tākaka and Riwaka that were found by a surveying party; and finally in 1878, the Otago Witness published an additional account from a farmer and his shepherd.[69] An 86-year-old woman, Alice McKenzie, claimed in 1959 that she had seen a moa in Fiordland bush in 1887, and again on a Fiordland beach when she was 17 years old. She claimed that her brother had also seen a moa on another occasion.[70] In childhood, Mackenzie saw a large bird that she believed to be a takahē, but after its rediscovery in the 1940s, she saw a picture of it and concluded that she had seen something else.[71]

An early 20th-century reconstruction of a moa hunt

Some authors have speculated that a few Megalapteryx didinus may have persisted in remote corners of New Zealand until the 18th and even 19th centuries, but this view is not widely accepted.[18] Some Māori hunters claimed to be in pursuit of the moa as late as the 1770s; however, these accounts possibly did not refer to the hunting of actual birds as much as a now-lost ritual among South Islanders.[72] Whalers and sealers recalled seeing monstrous birds along the coast of the South Island, and in the 1820s, a man named George Pauley made an unverified claim of seeing a moa in the Otago region of New Zealand.[73][69] Occasional speculation since at least the late 19th century,[74][75] and as recently as 2008,[76] has suggested that some moa may still exist, particularly in the wilderness of South Westland and Fiordland. A 1993 report initially interested the Department of Conservation, but the animal in a blurry photograph was identified as a red deer.[77][78] Cryptozoologists continue to search for them, but their claims and supporting evidence (such as of purported footprints)[76] have earned little attention from experts and are pseudoscientific.[18]

The rediscovery of the takahē in 1948 after none had been seen since 1898 showed that rare birds can exist undiscovered for a long time. However, the takahē is a much smaller bird than the moa, and was rediscovered after its tracks were identified—yet no reliable evidence of moa tracks has ever been found, and experts still contend that moa survival is extremely unlikely, since they would have to be living unnoticed for over 500 years in a region visited often by hunters and hikers.[76]

Research history

[edit]
Sir Richard Owen holding the first discovered moa fossil and standing with a Dinornis skeleton, 1879
Owen's first bone fragment (first discovered moa fossil)

Joel Polack, a trader who lived on the East Coast of the North Island from 1834 to 1837, recorded in 1838 that he had been shown "several large fossil ossifications" found near Mt Hikurangi. He was certain that these were the bones of a species of emu or ostrich, noting that "the Natives add that in times long past they received the traditions that very large birds had existed, but the scarcity of animal food, as well as the easy method of entrapping them, has caused their extermination". Polack further noted that he had received reports from Māori that a "species of Struthio" still existed in remote parts of the South Island.[79][80]

Dieffenbach[81] also refers to a fossil from the area near Mt Hikurangi, and surmises that it belongs to "a bird, now extinct, called Moa (or Movie) by the natives". 'Movie' is the first transcribed name for the bird.[82][83] In 1839, John W. Harris, a Poverty Bay flax trader who was a natural-history enthusiast, was given a piece of unusual bone by a Māori who had found it in a river bank. He showed the 15 cm (6 in) fragment of bone to his uncle, John Rule, a Sydney surgeon, who sent it to Richard Owen, who at that time was working at the Hunterian Museum at the Royal College of Surgeons in London.[69]

Owen puzzled over the fragment for almost four years. He established it was part of the femur of a big animal, but it was uncharacteristically light and honeycombed. Owen announced to a skeptical scientific community and the world that it was from a giant extinct bird like an ostrich, and named it Dinornis. His deduction was ridiculed in some quarters, but was proved correct with the subsequent discoveries of considerable quantities of moa bones throughout the country, sufficient to reconstruct skeletons of the birds.[69] In July 2004, the Natural History Museum in London placed on display the moa bone fragment Owen had first examined, to celebrate 200 years since his birth, and in memory of Owen as founder of the museum. Since the discovery of the first moa bones in the late 1830s, thousands more have been found. They occur in a range of late Quaternary and Holocene sedimentary deposits, but are most common in three main types of site: caves, dunes, and swamps.

An excavation in Kapua Swamp, 1894
Palaeontologists working on moa bone deposits in the 'Graveyard', Honeycomb Hill Cave System: This cave is a closed scientific reserve

Bones are commonly found in caves or tomo (the Māori word for doline or sinkhole, often used to refer to pitfalls or vertical cave shafts). The two main ways that the moa bones were deposited in such sites were birds that entered the cave to nest or escape bad weather, and subsequently died in the cave and birds that fell into a vertical shaft and were unable to escape. Moa bones (and the bones of other extinct birds) have been found in caves throughout New Zealand, especially in the limestone/marble areas of northwest Nelson, Karamea, Waitomo, and Te Anau.

Moa bones and eggshell fragments sometimes occur in active coastal sand dunes, where they may erode from paleosols and concentrate in 'blowouts' between dune ridges. Many such moa bones antedate human settlement, although some originate from Māori midden sites, which frequently occur in dunes near harbours and river mouths (for example the large moa hunter sites at Shag River, Otago, and Wairau Bar, Marlborough).

Densely intermingled moa bones have been encountered in swamps throughout New Zealand. The most well-known example is at Pyramid Valley in north Canterbury,[84] where bones from at least 183 individual moa have been excavated, mostly by Roger Duff of Canterbury Museum.[85] Many explanations have been proposed to account for how these deposits formed, ranging from poisonous spring waters to floods and wildfires. However, the currently accepted explanation is that the bones accumulated slowly over thousands of years, from birds that entered the swamps to feed and became trapped in the soft sediment.[86]

Many New Zealand and international museums hold moa bone collections. Auckland War Memorial Museum – Tāmaki Paenga Hira has a significant collection, and in 2018 several moa skeletons were imaged and 3D scanned to make the collections more accessible.[87] There is also a major collection in Otago Museum in Dunedin.

In literature and culture

[edit]
Harder's illustration of a moa hunt

Heinrich Harder portrayed moa being hunted by Māori in the classic German collecting cards about extinct and prehistoric animals, "Tiere der Urwelt", in the early 1900s.

The moa was the most commonly used animal as a symbol of New Zealand before it was replaced by the kiwi in the early 20th century.[88]

Allen Curnow's poem, "The Skeleton of the Great Moa in the Canterbury Museum, Christchurch" was published in 1943.[89][90]

Potential revival

[edit]

The creature has frequently been mentioned as a potential candidate for revival by cloning. Its iconic status, coupled with the facts that it only became extinct a few hundred years ago and that substantial quantities of moa remains exist, mean that it is often listed alongside such creatures as the dodo as leading candidates for de-extinction.[91] Preliminary work involving the extraction of DNA has been undertaken by Japanese geneticist Ankoh Yasuyuki Shirota.[92][93]

Interest in the moa's potential for revival was further stirred in mid-2014 when New Zealand Member of Parliament Trevor Mallard suggested that bringing back some smaller species of moa within 50 years was a viable idea.[94] The idea was ridiculed by many, but gained support from some natural history experts.[95]

In July 2025, American biotechnology Colossal Biosciences announced early phases of plans to "revive" the South Island giant moa by adding moa genes to a related species in collaboration with the Ngāi Tahu Research Centre with funding from Peter Jackson.[96][97]

See also

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General:

Footnotes

[edit]

Notes

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

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The moa (order Dinornithiformes) comprised nine species of large, flightless birds that were endemic to and became extinct approximately 600 years ago. These herbivores ranged in size from the turkey-like little (Anomalopteryx didiformis), weighing around 34 kg, to the towering [South Island giant moa](/page/South Island giant moa) ( robustus), which stood up to 3.6 meters tall and weighed over 240 kg, making some species among the largest birds to have ever existed. They inhabited diverse ecosystems across the North and South Islands, browsing on leaves, fruits, and twigs with specialized beaks adapted for different feeding strategies, from grinding tough vegetation to selecting soft foliage. The moa's taxonomy has evolved since their initial description in the 19th century, with modern genetic analyses confirming nine species divided into six genera: Anomalopteryx (bush moa), (giant moa), Emeus (eastern moa), Euryapteryx (broad-billed moa), Megalapteryx (upland moa), and Pachyornis (heavy-footed moa). These genera are grouped into three families: Dinornithidae (), Emeidae (Emeus, Euryapteryx), and Dinornithidae s.l. (Anomalopteryx, Megalapteryx, Pachyornis). These birds lacked wings entirely, relying on powerful legs for movement in forested and open habitats, and exhibited extreme sexual size dimorphism in some species, where females were significantly larger than males—up to three times heavier in . Fossil evidence, including bones, eggs, and ancient DNA, reveals they diversified during the Pleistocene and thrived in isolation until human arrival around 1280 CE. Polynesian settlers, known as , hunted moa intensively for food, using them as a primary protein source and crafting tools from their bones, leading to rapid population collapse within 100–300 years of first contact. Habitat modification through fire for and the introduction of dogs and rats further accelerated their demise, with the last moa vanishing by the late 15th to early ; genetic studies show no signs of pre-human decline, underscoring anthropogenic causes. Today, moa remains inform conservation efforts for New Zealand's surviving flightless birds, like the kiwi and takahe, by highlighting vulnerability to introduced predators and habitat loss, while ongoing discussions explore reviving them via .

Description

Physical Morphology

Moa possessed a highly specialized skeletal morphology characteristic of flightless ratites, optimized for terrestrial existence without reliance on flight. Their skeletons entirely lacked any osseous remnants of wings, including reduced coracoids or scapulae; the pectoral girdle was minimized to a simple scapulocoracoid devoid of a , setting them apart from other ratites like ostriches and emus that retain vestigial wing elements. This complete absence of structures underscored their evolutionary divergence toward ground-dwelling life. The hindlimbs formed the dominant structural feature, with robust femora, tibiotarsi, and adapted to bear substantial weight and facilitate movement across varied terrains. In the family Dinornithidae, proportions typically followed a of approximately 1:2, reflecting adaptations for stability and efficient striding similar to those in modern ratites such as ostriches, though moa exhibited greater overall limb robustness in certain taxa to withstand biomechanical stresses. The tibiotarsus featured a distinct sulcus extensorius terminating near the medial condyle, while the displayed prominent hypotarsal ridges for muscle attachment, enhancing propulsion and support. Neck vertebrae were elongated in browsing genera, with Dinornithidae possessing 29–30 presacral vertebrae to enable reaching elevated foliage, a configuration analogous to the flexible cervical structure in ostriches but more pronounced for herbivorous . Cranial morphology varied significantly across moa genera, particularly in bill shape, which reflected dietary specializations. For instance, species in the genus exhibited a hooked bill, suited for tearing tough vegetation, contrasting with the straighter, more delicate bills in genera like Megalapteryx. A 2024 genomic study of the little bush moa (Anomalopteryx didiformis) revealed small eyes, suggesting adaptations for low-light forest environments and reliance on other senses like olfaction. These skeletal variations highlight the diverse anatomical strategies within moa for exploiting New Zealand's prehistoric ecosystems.

Size and Variation

Moa species displayed considerable variation in body size, ranging from relatively small forms to some of the largest known avian megafauna. The genus Dinornis included the giants among them, with females reaching heights of up to 2 meters at the back and weighing as much as 242 kg, while full stature with the neck outstretched could exceed 3 meters. In contrast, smaller species such as Emeus crassus stood approximately 1.5 meters tall and weighed between 36 and 79 kg. These estimates derive from measurements of subfossil bones and reconstructions accounting for posture and soft tissue. Sexual dimorphism was particularly pronounced in Dinornis, exhibiting extreme reversed size differences where females were substantially larger than males. Bone metrics, combined with ancient DNA analysis confirming sex, reveal that the largest Dinornis females were about 150% taller and 280% heavier than the largest males, with males weighing 34–85 kg. This dimorphism, determined from femur and tibiotarsus dimensions, likely influenced mating systems and resource partitioning, though it was less extreme in smaller moa genera. Comparisons to other extinct megafauna highlight the Dinornis moa's impressive scale, akin to the elephant birds (Aepyornithidae) of Madagascar, which reached similar heights but greater mass up to 500 kg. Bone histology studies indicate that Dinornis achieved their size through accelerated juvenile growth rates, attaining skeletal maturity in nearly a decade—far longer than the sub-year period typical of modern birds—yet comparable to the protracted development in other ratite giants. These growth patterns, evidenced by lines of arrested growth in long bone cortices, underscore the moa's adaptation to a predator-free environment. Factors driving this size variation stem from island gigantism in New Zealand's isolated ecosystems, where the absence of mammalian competitors and predators allowed ratites to evolve larger bodies for accessing diverse vegetation layers. Larger forms like Dinornis likely benefited from reduced predation pressure and abundant resources, promoting gigantism as an evolutionary advantage in this fragmented, temperate archipelago.

Feathers and Soft Tissues

Moa feathers were primarily structured for insulation and rather than flight, featuring a central rachis with barbs and barbules forming vaned surfaces, often accompanied by an aftershaft—a secondary shaft branching from the main one, characteristic of birds—to enhance thermal retention in varied environments. These feathers measured up to 23 cm in length and exhibited simple, non-aerodynamic forms, with over 1,065 specimens documented from subfossil deposits. Preservation of moa feathers and soft tissues occurred mainly through in arid systems and dry sediment layers, such as those in , where cool, low-humidity conditions minimized degradation; rare examples include muscle attachments, ligaments, and from species like Dinornis robustus at sites like Knobby Range. impressions, revealing coarse textures with elevated papillae on the neck of Emeus crassus and scales on the tarsometatarsus of D. robustus, have been found in sediments and even embedded in coprolites from rockshelters like Sawers. These Holocene-era remains, dated via radiocarbon to around 861 ± 30 years BP in some cases, provide direct evidence of non-skeletal anatomy. Color patterns in moa feathers, determined through analysis of preserved specimens and , typically graded from tan or light brown at the base to dark brown or black at the tips, suggesting melanin-based pigmentation for earthy tones suited to understories. In Dinornis species, hues ranged from brown to black, while Megalapteryx didinus displayed grey to reddish-brown variations, with minimal fading observed in subfossil feathers compared to modern analogs like the . Genetic sequencing from feather calami confirmed species-specific patterns, such as white-tipped feathers in the heavy-footed moa (Pachyornis elephantopus), enabling plumage reconstructions without evidence of structural . Soft tissue adaptations in moa included thick, coarse skin with prominent papillae, likely providing protection against environmental abrasions or predators like , as seen in preserved neck samples from E. crassus. Leg feathering extended to the base of the in upland like M. didinus, an inferred for insulation in , snowy habitats. These features, preserved through exceptional taphonomic conditions, highlight moa's reliance on robust for survival in isolation.

Classification and Evolution

Taxonomy

The moa (Aves: Dinornithiformes) are classified within three families: Dinornithidae, Emeidae, and Megalapterygidae, encompassing six genera and nine species based on integrated morphological and molecular evidence. The genera include Dinornis (giant moa), Megalapteryx (upland moa), Anomalopteryx (little bush moa), Pachyornis (heavy-footed moa), Emeus (dwarf moa), and Euryapteryx (broad-billed moa). The recognized species are: Anomalopteryx didiformis, Dinornis novaezealandiae, Dinornis robustus, Emeus crassus, Euryapteryx curtus (including subspecies E. c. curtus and E. c. gravis), Megalapteryx didinus, Pachyornis australis, Pachyornis elephantopus, and Pachyornis geranoides. This taxonomy reflects a consensus established through ancient DNA analyses of mitochondrial sequences from over 200 subfossil specimens, which resolved longstanding uncertainties in species delimitation. Historical classifications began with the initial descriptions by Richard Owen in the 1840s, who named the genus Dinornis based on fragmentary bones from New Zealand, initially recognizing multiple species within it such as Dinornis giganteus (1843) and Dinornis curtus (1846). Early 19th- and 20th-century efforts proposed up to 64 species across 20 or more genera, relying primarily on morphological variations in bones like femurs and tibiotarsi, leading to fragmented nomenclature. By the mid-20th century, classifications stabilized somewhat, with estimates of around 20–27 species in fewer genera, as summarized in works like Archey (1941) and Oliver (1949). Significant revisions occurred in the late 20th century through detailed osteological studies, reducing the count to 11 species in six genera by Worthy and Holdaway (2002). The advent of ancient DNA in the 2000s prompted further refinements, with mitochondrial control region and protein-coding gene sequences demonstrating that apparent morphological diversity often reflected sexual dimorphism or geographic variation rather than distinct species. For instance, Bunce et al. (2009) used DNA from 263 specimens to confirm nine species, synonymizing forms like Euryapteryx gravis with E. curtus and erecting the family Megalapterygidae for Megalapteryx based on deep genetic divergence. These molecular insights integrated with morphology in subsequent works, such as Worthy et al. (2012), which provided revised diagnoses and new combinations for all taxa. Type specimens and holotypes for moa species are primarily housed in institutions like History Museum, London (formerly British Museum of Natural History), with examples including the lectotype of novaezealandiae (left tibiotarsus, BMNH 18591) and the holotype of Megalapteryx didinus (incomplete skeleton, BMNH A.16). Other key types, such as the tibiotarsus holotype of curtus (BMNH 23558), have been rediscovered and re-evaluated in recent studies. Significant collections, including potential paratypes and subfossil material, are also maintained at the Tāmaki Paenga Hira, which holds thousands of moa bones from sites like and swamps. Debates on species validity persist, particularly regarding lumping versus splitting, where morphological often suggest more taxa than genetic supports; for example, clinal size variations in Euryapteryx have led to questions about the discreteness of subspecies boundaries. has clarified some issues, such as confirming in (with females up to twice the size of males), but nuclear is needed to resolve phylogeographic structuring within populations, as mitochondrial haplotypes alone may overestimate diversity. Ongoing analyses emphasize integrating multi-locus genetic with to stabilize the further.

Evolutionary Relationships

The moa (Dinornithiformes) are derived from volant paleognath ancestors that originated in the during the , approximately 104–115 million years ago, before migrating southward via overseas dispersal to Gondwana-derived landmasses, including (the ancient landmass encompassing modern ), between 80 and 53 million years ago. These ancestors, part of the basal avian lineage , were capable of flight, with molecular and morphological evidence indicating an ancestral body mass of 3.8–5.5 kg. Flightlessness evolved independently in ratites, including moa, after their isolation on following the breakup of , likely as an adaptation to the predator-free environment. Following colonization, moa underwent an , diversifying into multiple that occupied distinct herbivorous niches in the absence of competing non-volant mammals. This radiation filled ecological roles analogous to large and mammals elsewhere, with specializing in foliage at varying heights—from low-lying to tall shrubs and trees—based on beak morphology and body size adaptations evident in subfossil remains. The diversification was facilitated by Zealandia's tectonic and climatic changes, allowing moa to exploit a range of and habitats without mammalian herbivores. A key evolutionary milestone was the development of gigantism, with some moa species reaching masses up to 242 kg, driven by the lack of predation and interspecific competition in this isolated ecosystem. This size increase occurred post-flight loss and is paralleled in other island ratites, reflecting convergent evolution in response to resource abundance and safety. However, the fossil record reveals gaps, with the oldest confirmed moa remains—bones and eggshells from the St Bathans Fauna—dating to the late Early Miocene, approximately 19–16 million years ago, indicating two distinct taxa already present by then. The full morphological and species radiation, encompassing nine recognized species, intensified during the Pliocene and Pleistocene, approximately 5–0.01 million years ago, coinciding with cooling climates and habitat fragmentation.

Phylogeny

The moa (Dinornithiformes) represent an extinct order of flightless birds within the , with phylogenetic analyses placing them in a close relationship to the volant tinamous (Tinamiformes), rendering the traditional clade paraphyletic. Early molecular studies using (mtDNA) supported a basal position for moa among ratites, but comprehensive analyses incorporating both mitochondrial and nuclear genomes from ancient subfossils have refined this to show moa as the to tinamous, with strong bootstrap support (>95%) in maximum likelihood trees. In this topology, ostriches () form the basal lineage, followed by rheas (), then the moa-tinamou clade, with emus and cassowaries () sister to kiwis (Apterygiformes) and (Aepyornithiformes). A 2024 nuclear genome assembly of the little bush moa further corroborated the moa-tinamou sister relationship using , enhancing understanding of their genetic structure. Among moa genera, molecular evidence from mtDNA sequences extracted from subfossil bones indicates divergences dating to the , with the estimated at approximately 18.5 million years ago (95% CI: 15.1–23.2 Ma). Major generic splits include the basal divergence of Megalapteryx around 12.3 Ma, followed by separations between and other lineages (~15 Ma), and between Pachyornis and Anomalopteryx (~9.7 Ma), reflecting a relatively ancient radiation within . Later studies using expanded mtDNA datasets and Bayesian divergence dating revised these estimates downward, placing the basal moa split at ~5.8 Ma and the Dinornithidae-Emeidae divergence at ~5.3 Ma (95% HPD: 3.1–9.0 Ma), linking diversification to Miocene tectonic uplift of the . These timelines are derived from radiocarbon-dated samples (1,000–19,000 years old) analyzed under strict protocols to minimize contamination. Morphological phylogenies, often based on skeletal traits such as leg bone proportions and bill shape, have conflicted with genetic data; for instance, traditional classifications grouped species by inferred browsing versus grazing habits derived from bill morphology, but mtDNA trees show these traits evolved convergently within clades rather than defining monophyletic groups. High genetic diversity in Megalapteryx contrasts with its low morphological variation, leading to up to 54% misclassification of specimens in morphology-based schemes, while nuclear and mtDNA analyses confirm three families (Dinornithidae, Emeidae, Megalapterygidae) with six genera. Consensus phylogenies from 2010s studies integrate from over 200 subfossil specimens, producing a robust tree where the moa-tinamou is supported by 27 nuclear genes and complete mitochondrial genomes, with flightlessness evolving independently multiple times across ratites. This framework, visualized in Bayesian maximum trees, highlights convergent adaptations in bill and limb morphology driven by similar ecological pressures, rather than shared ancestry.

Distribution and Habitat

Overall Range

The moa, a group of extinct flightless birds belonging to the order Dinornithiformes, were endemic to , with subfossil remains recovered exclusively from the , , and , but absent from the offshore approximately 800 km to the east. This mainland-restricted distribution reflects the archipelago's long-term isolation, as separated from the supercontinent around 83–52 million years ago and became fully isolated from by the , approximately 25 million years ago, preventing colonization by terrestrial vertebrates like moa across oceanic barriers. Moa occupied diverse habitats across these islands from the onward, becoming particularly abundant during the until their rapid around 1300 CE, coinciding with Polynesian . and subfossil indicates that moa populations were widespread prior to arrival, with adapted to forested, subalpine, and coastal environments, though densities varied regionally—higher in eastern lowlands and lower in western mountainous areas of the . A 2024 study further reveals that moa retreated to specific refugia in isolated, cold mountainous areas during their decline, including Mount Aspiring on the and the Ruahine Range on the , where six survived longest before . Subfossil site concentrations provide key insights into moa distribution patterns, with notable accumulations in cave systems of in the southwestern , where bones and soft tissues have been preserved in dry, protected environments, and in peat bogs of the region on the , where acidic, waterlogged conditions facilitated the preservation of skeletal material from multiple individuals. These sites, along with swamp deposits and dune sands elsewhere, reveal non-random biogeographic patterns, such as higher trackway densities in northern areas and coprolite concentrations in southern forests, underscoring moa's role as engineers across isolated island biogeography.

South Island Environments

Moa on the occupied a diverse array of habitats spanning from coastal lowlands to alpine zones, primarily consisting of forests, shrublands, and tussock grasslands. These environments provided essential cover and forage, with moa species adapting to the island's varied topography and climate, which ranges from wet western rainforests to drier eastern plains. Key regions included the West Coast, where dense rainforests dominated by southern beech () and podocarps supported browsing moa such as the ( robustus), which exploited the abundant vegetation. In contrast, the eastern Otago plains featured open tussock grasslands and shrublands, favoring grazing species like the (Emeus crassus), which thrived in these more arid, low-elevation areas with grasses and low shrubs. Pollen and coprolite analyses from South Island sites reveal the flora associated with moa habitats, including podocarps (e.g., Dacrydium cupressinum, ), grasses (), and southern , indicating a reliance on mixed forest and grassland ecosystems. For instance, coprolites from subalpine caves contain remnants of leaves and grass seeds, alongside shrubs like Dracophyllum and Myrsine, underscoring moa interactions with both wooded and open terrains. Altitudinal variation influenced moa distribution and morphology, with larger species such as predominantly inhabiting lowlands and coastal forests, while smaller forms like the (Megalapteryx didinus) were more common in highland shrublands and grasslands above the treeline. This pattern reflects adaptations to resource availability across elevations from to over 1,000 meters.

North Island Environments

The of provided moa with warmer, more humid environments compared to the , featuring subtropical broadleaf and podocarp forests, volcanic plateaus with seral shrublands, and coastal dune systems that supported a diversity of moa species adapted to these niches. These habitats were characterized by higher rainfall and milder temperatures, fostering dense vegetation that differed from the cooler, more altitudinally varied landscapes. Subfossil evidence indicates that moa occupied lowland to subalpine zones, with species like the ( novaezealandiae) thriving in coastal forests and shrublands from North Cape to . Key subfossil sites on the include peatlands in the Hauraki Plains near , where preserved moa bones and fragments have been recovered from deposits, reflecting the preservation potential of these acidic, waterlogged environments for smaller-bodied . In the [Te Urewera](/page/Te Urewera) region, a cave near Lake Waikaremoana yielded remains of at least five moa individuals in 1969, highlighting forested uplands as important refugia for taxa in this remote, humid area dominated by podocarp-broadleaf associations. These sites supported smaller, more agile moa , such as the little bush moa (Anomalopteryx didiformis) and Pachyornis mappini, which were adapted to navigating dense undergrowth and mosaics rather than open terrains. Moa on the were closely associated with angiosperm-dominated forests, including broadleaf understories beneath kauri () canopies and scattered hard beech (Nothofagaceae) stands, which provided browse in wet, tall forest ecosystems. Subfossil assemblages from these vegetation types show reliance on such habitats, with species like Euryapteryx curtus favoring lowland shrublands interspersed with open podocarp-broadleaf forests. Regarding range dynamics, most moa taxa were endemic, with subfossils indicating exclusivity for species like novaezealandiae and Pachyornis mappini; however, Euryapteryx curtus represents a case of overlap, with genetic evidence from subfossils suggesting recent interchange between islands via Pleistocene land connections.

Ecology and Behavior

Diet and Foraging

Moa were strictly herbivorous, relying on plant material for sustenance, with direct evidence derived from preserved contents and coprolites that reveal a diet dominated by foliage, twigs, seeds, and fruits. Larger , such as those in the genera and Megalapteryx, primarily engaged in browsing, consuming leaves and twigs from shrubs and trees, including podocarps like , where over 3,000 leaves and numerous seeds have been documented in single samples. In contrast, smaller like those in the genus Anomalopteryx primarily browsed on forest plants, including shrubs such as , with coprolites showing from woody vegetation and ferns. Analysis of gastroliths—polished stones retained in moa gizzards to aid in grinding tough vegetation—often yields adhering plant fragments and pollen that corroborate this dietary profile. For instance, gizzard contents from multiple sites show sheared twigs comprising up to 30% of the organic volume, indicating deliberate browsing on woody species such as Olearia virgata, Rubus spp., and Coprosma spp., with podocarp remains prominent. Pollen trapped in association with these gastroliths and in coprolites further indicates consumption of ferns and podocarps, with fern spores and podocarp pollen frequently recovered, suggesting ferns formed a supplementary but notable component of the diet across genera. Coprolite studies expand this evidence, identifying up to 58 pollen taxa per sample, including those from dicot herbs, grasses, and lianas, reflecting a broad opportunistic intake. Dietary niche partitioning among moa genera minimized , with taller species like Pachyornis exploiting higher canopy layers through on elevated twigs and fruits, while smaller, bush-dwelling forms such as Euryapteryx targeted vegetation, herbs, and ground-level . This partitioning is evident in assemblages from shared habitats, where larger moa show higher proportions of woody podocarp material, and smaller ones feature more pollen alongside , supporting a layered exploitation of and resources. Such strategies likely enhanced coexistence in New Zealand's pre-human ecosystems, with contents from 23 individuals across sites confirming genus-specific preferences without overlap in primary forage heights.

Reproduction and Growth

Moa eggs were notably large and varied in size across species, ranging from approximately 120 mm by 95 mm (about 0.06 kg) for smaller taxa to 240 mm by 178 mm (up to 4.5 kg) for giants like Dinornis, with thick shells measuring 0.50–1.89 mm in thickness. These eggs featured species-specific pore structures, such as slit-like pores in thicker shells of larger moa and finer dot-like pores in thinner ones, and were typically laid in simple ground scrapes or rock shelters lined with coarse vegetation, stripped bark, and other plant material, akin to nests of extant ratites like emus. The breeding season for moa likely occurred in late spring to early summer, inferred from pollen and seed analyses of coprolites associated with eggshell fragments and nesting debris, which indicate consumption of seasonally available plants during warmer periods. Moa exhibited a K-selected life-history with extended juvenile development, as revealed by annual cortical growth marks in long bones, which were frequent and indicated slow overall growth despite accelerated phases in larger species like those in Dinornithidae. Juveniles reached skeletal maturity in 5–10 years, with smaller Euryapteryx species maturing around 4 years at 20 kg and larger ones exceeding 9 years at over 80 kg, and —such as reversed size differences in where females were larger—emerged early in . Parental care was minimal and primarily male-driven, similar to emus, with ancient DNA from eggshell surfaces showing predominantly male genotypes in contact with the exterior of eggs from species like Dinornis and Euryapteryx, suggesting males incubated the fragile, thin-shelled eggs to avoid breakage by heavier females. Clustered subfossil eggs and fragments at nesting sites further support limited post-hatching care, as the eggs were likely left unguarded after incubation.

Locomotion and Physiology

Moa were obligate bipedal walkers, relying on robust hindlimbs adapted for graviportal locomotion to support their massive body , which ranged from 30 to 250 kg across . Fossil trackways reveal a striding with stride lengths of 0.98–1.07 m, indicating a , energy-efficient walking pattern suited to forested and terrains. Their long necks likely contributed to balance during movement, countering the forward shift of the center of caused by their upright posture, similar to extant ratites like ostriches. Estimated locomotion speeds for moa were modest, typically 2.5–7.2 km/h based on leg bone lengths and stride patterns, far below the capabilities of ratites like emus. Trackway analyses from – deposits confirm average speeds around 2.6 km/h, with variations reflecting subtle changes in stride but no evidence of rapid acceleration. Larger species, such as those in the Dinornis, exhibited stouter leg bones that prioritized load-bearing over speed, rendering them relatively slow and less agile compared to smaller moa or modern flightless birds. As ratites, moa possessed a low , approximately 60–80% of that predicted for non-passerine birds of equivalent size, enabling efficient in nutrient-poor, seasonal habitats. This hypometabolic strategy, coupled with lower body temperatures (around 37–38°C versus 40–41°C in flying birds), minimized daily energy expenditure and supported long lifespans, potentially exceeding 50 years in the absence of predators. Such physiological traits aligned with their herbivorous lifestyle, allowing sustained foraging without high caloric demands. Sensory adaptations in moa emphasized diurnal activity, with endocranial fossils indicating visual processing comparable to that of emus and rheas, but without specialization for low-light conditions. Relative eye size was small, and orbital morphology showed no expansion for enhanced nocturnality, suggesting reliance on broad daylight vision for detecting environmental cues rather than olfactory or auditory dominance seen in nocturnal ratites like kiwis. The prolonged isolation of moa in predator-free ecosystems led to reduced encephalization quotients (mean EQ 0.379), lower than in other ratites (0.539), potentially reflecting diminished selective pressure for agile evasion or complex anti-predator behaviors. Giant exhibited graviportal builds with limited limb mobility, increasing vulnerability to novel mammalian hunters like humans and dogs, as their prioritized stability over rapid flight responses.

Extinction

Timeline and Evidence

The extinction of moa occurred rapidly following the arrival of Polynesian settlers in around 1300 CE, with a complete disappearance across all species by approximately 1440 CE. of moa remains indicates a swift decline, with no evidence of pre-existing population crashes in the preceding millennia. This timeline is supported by Bayesian modeling of calibrated radiocarbon ages from non-archaeological sites, which show moa persistence for only 100–150 years after human colonization before vanishing from the fossil record. Key evidence comes from accelerator mass spectrometry (AMS) radiocarbon dating of bones and eggshells recovered from natural deposits. For instance, analysis of 270 bone collagen samples and 93 eggshell fragments calibrates the youngest reliable dates to between 1404 and 1428 CE, primarily from South Island sites such as Bulmer Cavern. These dates suggest the last moa survivors lingered in isolated refugia on the South Island until the mid-15th century (around 1440 CE), though some outliers have been critiqued for potential contamination or reworking in sediments. High-precision chronologies using probabilistic modeling of 111 vetted radiocarbon dates further confirm this narrow extinction window, emphasizing the role of subfossil stratigraphy in distinguishing pre- and post-extinction layers. Site-specific timelines reveal variations linked to patterns, with moa on the disappearing earlier than on the due to denser initial colonization and resource use there. remains cease abruptly around 1400 CE, while populations endured slightly longer in remote areas, as evidenced by dated eggshells from multiple sites spanning 1300–1415 CE. Prior to , moa populations were estimated at around 2 million individuals across all nine , based on allometric models of body mass, , and distribution derived from femur measurements and phylogenetic analyses; however, estimates vary widely from ~58,000 to 2.5 million. These estimates indicate , viable numbers with no genetic bottlenecks until the final decades, underscoring the abrupt nature of the collapse.

Causes and Impacts

The extinction of moa was primarily driven by intense hunting pressure from settlers, who targeted the birds for and feathers following their arrival around 1300 CE. Archaeological evidence, including large moa-hunting sites and cooking ovens, indicates that overhunting was the dominant factor, with all nine vanishing within approximately 100–150 years of colonization. Models suggest that even hunting rates of about 1 moa per person per year could account for the rapid depletion, even with a low population density of around 1,000–2,000 individuals during the peak period. exacerbated this pressure, as used fire to clear forests for and settlements, converting productive woodland habitats into grasslands and reducing available browse for moa by the . This particularly affected eastern regions, where moa populations were concentrated, limiting their access to food sources and accelerating decline. Secondary effects included the introduction of kurī (Polynesian dogs) and kiore (Polynesian rats), which assisted in moa, acted as additional predators or competitors, disturbed nesting sites, and contributed to overall ecological stress. However, is considered unlikely as a significant factor, given New Zealand's long isolation from pathogens and the absence of for pre-human declines in moa genetic records. The moa's extinction had profound impacts, as these large herbivores played a key role in control, preventing overgrowth of certain plants and maintaining diverse vegetation structures. Their loss led to shifts in composition, with some tree expanding unchecked and reduced regeneration in others due to the absence of moa-mediated , fundamentally altering New Zealand's pre-human ecosystems.

Human Interactions

Discovery and Initial Research

The discovery of moa remains began in the 1830s when European settlers in encountered large bones in swamps and middens, corroborating longstanding oral traditions of giant flightless birds known as moa. These early finds were sporadic, often unearthed during land clearance or reported by communities, but lacked systematic collection until the 1840s. Walter Mantell, a naturalist and colonial official, played a pivotal role by gathering extensive moa bone assemblages from sites such as Waingongoro in South Taranaki and Awamoa in , where he documented bones in association with ancient cooking sites (middens). His collections, shipped to Britain, provided crucial material for anatomical analysis and helped validate the existence of these extinct giants. In 1839, a single fragment from an unknown bird reached British anatomist via a in , prompting his initial identification of a massive struthious (ostrich-like) . By 1843, Owen formally named the genus based on additional fragments, including those from Mantell's early shipments, reconstructing the bird's form from partial remains and declaring it extinct. This naming ignited international interest, positioning the moa as a key example of 's unique paleontological heritage and spurring further specimen hunts. Systematic expeditions intensified in the 1850s and , with geologist Julius von Haast leading excavations at swamp sites like Glenmark in North Canterbury starting in 1859, yielding cartloads of articulated bones that enabled the first complete skeleton mounts. explorations in the 1860s and 1870s, particularly in regions like Takaka and Moa Bone Point , uncovered preserved remains in stratified deposits, facilitating reconstructions of multiple species and revealing insights into their size—up to 3.6 meters tall. These efforts, often collaborative between local scientists and guides, filled museums in and with moa fossils. Early research was marred by debates over the moa's temporal context, with some scholars arguing for an ancient extinction predating human arrival, while others posited recent coexistence based on unstratified bone scatters on plains. The 1870s "moa-hunter" controversy, centered on figures like Haast and James Hector, hinged on whether Māori had hunted the birds; stratigraphic evidence from middens and caves, showing moa bones layered with human artifacts, ultimately resolved this in favor of a recent, human-influenced extinction around the 15th century. This stratigraphic approach marked a shift toward rigorous paleontological methods in New Zealand science.

Modern Scientific Studies

Modern scientific studies on moa have leveraged advanced molecular techniques to uncover details about their , diet, and evolutionary history since the mid-20th century. () extraction from subfossil s and eggshells has been pivotal, with full mitochondrial s (mitogenomes) sequenced as early as 2001 from two moa species, providing initial confirmation of their placement within the alongside kiwis and tinamous. Subsequent efforts in the 2009–2020s expanded this work, including a 2010 study that analyzed complete mitogenomes from multiple moa taxa to resolve phylogenetic relationships, revealing independent flight losses in ratites and supporting a close affinity between moa and South American tinamous. By 2024, international collaborations produced a draft nuclear assembly of the little bush moa (Anomalopteryx didiformis) from a subfossil , achieving ~900 Mb coverage and estimating a of 1.07–1.12 Gb, further solidifying moa's basal position in the ratite tree through phylogenomic analyses of 1,448 nuclear loci. Stable isotope analyses of have provided key insights into moa dietary habits, particularly through ratios of carbon (δ¹³C) and (δ¹⁵N). These studies reconstruct behaviors, showing niche partitioning among ; for instance, larger moa like the giant moa (Dinornis robustus) exhibited higher δ¹⁵N values indicative of a diet focused on browse from taller in more open or drier habitats, while smaller consumed a broader range of plants. Complementary research integrating isotopes with metabarcoding confirms that moa supplemented their plant-based diets with ferns, mosses, and ectomycorrhizal fungi, highlighting their role in forest ecosystems. Optimal sampling protocols for moa , established in 2013, ensure reliable δ¹³C and δ¹⁵N measurements by targeting the cortical region, minimizing diagenetic alteration in subfossils up to 1,000 years old. Recent advances have focused on proteomic and genomic applications to subfossils. Proteomic analysis of ancient eggshells, though less common for moa, builds on DNA methods to infer sex ratios; a 2010 study extracted mitochondrial and nuclear DNA from moa eggshell surfaces, determining that larger species likely had males incubate eggs due to thin shell structures prone to breakage by females. This approach revealed highly skewed sex ratios (up to 1:5 male-to-female) in fossil assemblages, attributed to behavioral biases in nesting and deposition. Analyses of moa remains have informed models of post-glacial recolonization, showing eastern moa populations contracted to high-altitude refugia during the Last Glacial Maximum, mirroring current retreats of extant flightless birds amid warming. Collaborative efforts, including those at the Museum of New Zealand Te Papa Tongarewa, have driven ongoing excavations and analyses. Te Papa's collections, housing over 1,000 moa subfossils, support multidisciplinary research, such as isotopic and DNA studies from sites like Pyramid Valley, revealing dietary and genetic diversity. International phylogenomic projects, involving institutions in New Zealand, the UK, and Australia, have integrated moa data with ratite genomes to model adaptive evolution, including sensory adaptations like enhanced olfaction for foraging in dense forests. These initiatives underscore moa's utility as a model for understanding extinction dynamics in isolated ecosystems.

Cultural and Literary Significance

In , the word "moa" originates from Proto-Polynesian *moa, referring to or domestic , reflecting the bird's classification as a large, edible bird upon Polynesian arrival in around 1300 CE. Oral traditions preserved accounts of moa hunts, with (tribes) recounting communal expeditions using spears, traps, and dogs to capture the flightless giants in forested uplands, emphasizing their role as a vital protein source that sustained early settlers. These narratives also include whakataukī (proverbs) that acknowledged the moa's rapid decline, such as references to its disappearance as a for irretrievable loss, demonstrating early recognition of by the 15th century. Māori utilized moa remains extensively in material culture, crafting fishhooks, needles, ornaments, and spear points from their robust bones and claws, which were valued for durability in tools and adornments. Eggs served as water containers, underscoring the bird's integration into daily life before overhunting led to its demise. Post-extinction, moa featured in whakataukī symbolizing the vulnerability of communities amid European , as in expressions equating their fate to fears of cultural erasure. In inspired by , moa have symbolized a lost prehistoric world and human impact on , appearing in narratives that mythologize the islands' unique . For instance, 19th-century accounts like J.W. Harris's descriptions in scientific journals framed moa as emblems of evolutionary marvels and colonial discovery. Modern continues this motif, with moa embodying themes of and in works that blend , art, and . Today, moa serve as an enduring icon of New Zealand's crisis, featured in educational programs at institutions like Otago Museum to illustrate human-induced extinction and conservation needs. In , such as rural murals depicting extinct species, moa evoke ecological fragility and the urgency of protecting remaining endemic wildlife, reinforcing messages of . This symbolism extends to public discourse, where moa represent the irreplaceable loss of Aotearoa's ancient ecosystems.

De-Extinction Proposals

In the , early proposals for the moa emerged through initiatives like the Moa Revival Project, which aimed to sequence moa genomes and develop genetic proxies for all nine extinct species, beginning with the little bush moa (Anomalopteryx didiformis). This effort focused on using from museum specimens to reconstruct genetic material, with the goal of editing related living birds to recreate moa-like traits, though no viable hybrids were produced by the decade's end. By the 2020s, advancements in genome editing accelerated interest, culminating in a major 2025 announcement by Colossal Biosciences, a U.S.-based biotechnology firm, to pursue moa de-extinction in collaboration with New Zealand's Ngāi Tahu Research Centre and Canterbury Museum. The project targets the South Island giant moa (Dinornis robustus) and plans to sequence genomes for all nine moa species, building on prior work like the 2024 draft genome assembly of the little bush moa. Methods involve extracting ancient DNA from bones, using CRISPR-based multiplex editing to insert moa-specific genes (such as those for large size and flightlessness) into primordial germ cells of living relatives, and employing interspecies surrogacy for reproduction. Surrogate species under consideration include the tinamou, the moa's closest living relative, and the emu, valued for its larger size and flightless nature to better accommodate moa egg development. Colossal anticipates producing viable moa proxies within five to eight years, potentially by 2030–2033. As of November 2025, no further progress updates have been reported beyond the initial announcement. Significant challenges persist, including the incompleteness of moa genomes—early reconstructions in covered much but not all of the sequence, with gaps in degraded hindering full trait recreation. Technical hurdles involve scaling avian primordial cultures and ensuring surrogate compatibility, such as matching sizes and nutritional needs between emus or tinamous and moa embryos. Ethical concerns are prominent, particularly regarding ecological integration: reintroduced moa might disrupt modern ecosystems altered by invasive predators and habitat changes since the birds' around 600 years ago. Critics argue that hybrid proxies may not fulfill original ecological roles and could become invasive, while proponents emphasize cultural consultations with iwi like to incorporate indigenous knowledge and mitigate risks. Potential benefits include restoring moa as ecosystem engineers to regenerate native forests through and , enhancing resilience amid current extinctions. The project also promises spin-off technologies for conserving threatened birds, such as for disease resistance. However, risks of unintended invasiveness and the ethical over "playing " with extinct species underscore the need for rigorous before any release.

References

  1. https://pmc.ncbi.nlm.nih.gov/articles/PMC3977255/
  2. https://www.unsw.edu.au/newsroom/news/2016/01/new-zealand-s-extinct-moa-irreplaceable--research-reveals
  3. https://pmc.ncbi.nlm.nih.gov/articles/PMC11809649/
  4. https://pmc.ncbi.nlm.nih.gov/articles/PMC3652460/
  5. https://digimorph.geo.utexas.edu/specimens/Dinornithiformes/
  6. https://www.researchgate.net/figure/Cumulative-number-of-plant-genera-recorded-from-moa-gizzard-content-and-coprolite-samples_fig3_339089575
  7. https://teara.govt.nz/en/interactive/11363/moa-family-groupings-2009
  8. https://www.curtin.edu.au/news/media-release/human-settlement-key-to-extinction-of-new-zealands-iconic-moa-bird/
  9. https://www.adelaide.edu.au/newsroom/news/list/2024/07/24/new-zealands-flightless-birds-are-retreating-to-moa-refuges
  10. https://www.tandfonline.com/doi/full/10.1080/03014223.2012.665060
  11. https://pmc.ncbi.nlm.nih.gov/articles/PMC7668321/
  12. https://pmc.ncbi.nlm.nih.gov/articles/PMC3867382/
  13. https://www.science.org/doi/10.1126/sciadv.adj6823
  14. https://pubmed.ncbi.nlm.nih.gov/12968178/
  15. https://www.nzbirdsonline.org.nz/species/eastern-moa
  16. https://www.nature.com/articles/nature01848
  17. https://pubmed.ncbi.nlm.nih.gov/15959513/
  18. https://pmc.ncbi.nlm.nih.gov/articles/PMC6170582/
  19. https://www.pbs.org/wgbh/nova/article/gigantism-and-dwarfism-islands/
  20. https://pmc.ncbi.nlm.nih.gov/articles/PMC2817183/
  21. https://www.tandfonline.com/doi/full/10.1080/03036758.2012.704878
  22. https://www.pnas.org/doi/10.1073/pnas.0906660106
  23. https://www.researchgate.net/publication/273321608_Historical_moa_bone_collections_Aves_Dinornithiformes_at_Auckland_Museum-Clevedon_and_Kia_Ora
  24. https://academic.oup.com/auk/article/124/4/1449/5562698
  25. https://www.sciencedirect.com/science/article/pii/S0960982216312143
  26. https://academic.oup.com/sysbio/article/59/1/90/1726018
  27. https://academic.oup.com/mbe/article/31/7/1686/2925879
  28. https://www.pnas.org/doi/10.1073/pnas.0409435102
  29. https://media.australian.museum/media/Uploads/Journals/18092/1546_complete.pdf
  30. https://www.nature.com/articles/ncomms6436
  31. https://www.birdsnz.org.nz/wp-content/uploads/2022/03/Notornis_36_3-1989-pp-35-40.pdf
  32. https://www.nature.com/articles/hdy201548
  33. https://www.nature.com/articles/s41559-024-02449-x
  34. https://www.tandfonline.com/doi/pdf/10.1080/00288306.1979.10424226
  35. https://www.researchgate.net/publication/383306380_AN_OVERVIEW_OF_THE_ICHNOLOGY_OF_MOA_TRACKS_AND_OTHER_TRACES_FROM_THE_LATE_CENOZOIC_OF_NEW_ZEALAND
  36. https://www.nzbirdsonline.org.nz/species/south-island-giant-moa
  37. https://www.doc.govt.nz/documents/science-and-technical/sap240.pdf
  38. https://www.nzgeo.com/stories/lost-in-time/
  39. https://pmc.ncbi.nlm.nih.gov/articles/PMC3386916/
  40. https://www.pnas.org/doi/10.1073/pnas.1712337115
  41. https://researchportal.murdoch.edu.au/esploro/outputs/conferencePaper/Dinornis---An-insular-oddity-a/991005544305107891
  42. https://www.nzbirdsonline.org.nz/species/north-island-giant-moa
  43. https://www.birdsnz.org.nz/wp-content/uploads/2023/01/Holdaway_69_228-242.v3.pdf
  44. https://www.aucklandmuseum.com/discover/stories/blog/2023/Moa-than-meets-the-eye
  45. https://discover.stqry.app/pt/story/10674
  46. https://rsnz.onlinelibrary.wiley.com/doi/abs/10.1080/03014223.1990.10422598
  47. https://newzealandecology.org/nzje/1478/pdf
  48. https://pmc.ncbi.nlm.nih.gov/articles/PMC3801019/
  49. https://www.sciencedirect.com/science/article/abs/pii/S0277379121001992
  50. https://newzealandecology.org/nzje/3397
  51. https://pmc.ncbi.nlm.nih.gov/articles/PMC2941315/
  52. https://www.tandfonline.com/doi/pdf/10.1080/03014223.2000.9517613
  53. https://www.researchgate.net/publication/240512079_Moa_Aves_Dinornithiformes_nesting_material_from_rockshelters_in_the_semi-arid_interior_of_South_Island_New_Zealand
  54. https://www.nature.com/articles/nature03635
  55. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0099929
  56. https://www.tandfonline.com/doi/full/10.1080/03036758.2023.2264789
  57. https://besjournals.onlinelibrary.wiley.com/doi/10.1111/1365-2435.13904
  58. https://www.livescience.com/3857-giant-extinct-birds-grew-slow.html
  59. https://www.publish.csiro.au/an/ea08142
  60. https://karger.com/bbe/article/71/2/151/46918/Big-Birds-and-Their-Brains-Paleoneurology-of-the
  61. https://www.pnas.org/doi/10.1073/pnas.1314972111
  62. https://www.tandfonline.com/doi/full/10.1080/03036758.2012.658817
  63. https://www.sciencedirect.com/science/article/abs/pii/S0277379114003734
  64. https://www.pnas.org/doi/10.1073/pnas.2207609119
  65. https://onlinelibrary.wiley.com/doi/10.1111/ecog.04917
  66. https://www.heritage.org.nz/list-details/5688/Listing
  67. https://teara.govt.nz/en/artwork/37312/walter-mantell-riding-a-moa
  68. https://branchcollective.org/?ps_articles=gowan-dawson-on-richard-owens-discovery-in-1839-of-the-extinct-new-zealand-moa-from-just-a-single-bone
  69. https://www.universitypressscholarship.com/view/10.7208/chicago/9780226332871.001.0001/upso-9780226332734-chapter-004
  70. https://www.yorkshiremuseum.org.uk/collections/collections-highlights/giant-moa-skeleton/
  71. https://www.researchgate.net/publication/376756638_A_Short_Biography_of_Sir_Julius_von_Haast
  72. https://opac.geologie.ac.at/ais312/dokumente/HistGroup_GSNZ_46_19_27.pdf
  73. https://mro.massey.ac.nz/bitstreams/445f90a5-07a7-4943-9a2f-a2ffc3dc7bfb/download
  74. https://core.ac.uk/download/pdf/5093404.pdf
  75. https://aaanz.info/wp-content/uploads/2014/12/Tyler_Moa-hunting-in-the-Transactions.pdf
  76. https://philpapers.org/rec/THOBAW
  77. https://www.sciencedirect.com/science/article/abs/pii/S0277379116301548
  78. https://www.researchgate.net/publication/236596570_Identification_of_an_optimal_sampling_position_for_stable_isotopic_analysis_of_bone_collagen_of_extinct_moa_Aves_Emeidae
  79. https://www.tandfonline.com/doi/abs/10.1080/03036758.2013.813988
  80. https://www.pnas.org/doi/10.1073/pnas.0914096107
  81. https://www.sciencedirect.com/science/article/abs/pii/S0277379109003953
  82. https://www.sciencedaily.com/releases/2024/07/240725154812.htm
  83. https://collections.tepapa.govt.nz/topic/2507
  84. https://www.jstor.org/stable/2842167
  85. http://historyofgeology.fieldofscience.com/2011/01/ka-ngaro-i-te-ngaro-te-moa.html
  86. https://www.sciencelearn.org.nz/resources/2654-dead-as-the-moa-oral-traditions-show-that-early-maori-recognised-extinction
  87. https://www.ebsco.com/research-starters/zoology/maoris-hunt-moa-extinction
  88. https://www.smithsonianmag.com/smart-news/oral-history-suggests-maori-proverbs-bird-extinction-mirrored-fears-indigenous-groups-own-decline-180970225/
  89. https://www.nature.com/articles/130831a0
  90. https://journals.sagepub.com/doi/10.1177/0021989410376799
  91. https://otagomuseum.nz/education/module/maori-art
  92. https://www.sciencedirect.com/science/article/pii/S074301672300195X
  93. https://experiment.com/projects/sequencing-the-genome-of-the-extinct-moa
  94. https://pmc.ncbi.nlm.nih.gov/articles/PMC6265789/
  95. https://www.statnews.com/2018/02/27/moa-extinct-bird-genome/
  96. https://colossal.com/moa/
  97. https://www.sciencemediacentre.co.nz/2025/07/09/moa-de-extinction-plans-announced-expert-reaction/
  98. https://dnascience.plos.org/2024/09/19/genome-sequence-of-the-little-bush-moa-illuminates-avian-evolution/
  99. https://www.facebook.com/61557012407009/posts/a-bold-new-scientific-effort-is-underway-to-bring-one-of-earths-most-astonishing/122271528278233746/
  100. https://colossal.com/how-will-crispr-help-in-de-extinction/
  101. https://www.futuretimeline.net/blog/2025/07/11-moa-revival-future-timeline.htm
  102. https://www.science.org/content/article/effort-revive-new-zealand-s-extinct-moa-stirs-controversy
  103. https://www.theguardian.com/environment/2025/jul/11/de-extinction-extinct-giant-moa-bird-colossal-bioscience-aoe
  104. https://crisprmedicinenews.com/press-release-service/card/the-ngai-tahu-research-centre-has-entered-into-a-strategic-partnership-with-de-extinction-company-c/
  105. https://onlinelibrary.wiley.com/doi/10.1111/ele.70217
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