Upland Moa (Megalapteryx didinus)
The Upland Moa (Megalapteryx
didinus) was a small, abundant species of moa which lived in the mountainous areas
of South Island. It is particularly well-represented by soft tissue remains
including entire desiccated body parts with intact skin and feathers.
Upland Moa skeleton collected Mar 1987, Honeycomb Hill, Enduro, Map Grid 1385N 720E, New Zealand. Field Collection 1982-1988. CC BY-NC-ND licence. Te Papa (S.023700) |
Etymology
The Upland Moa is the only known member of the family
Megalapterygidae and of the genus Megalapteryx,
which is derived from the Greek words mega
(meaning “big”) and apteryx (meaning
“without wings”). The species name didinus
means “resembling a Dodo”: didus being a
Latinized generic name given to the Dodo (Raphus
cucullatus) by Carolus Linnaeus. The common name for this species
references its preferred habitat.
Habitat
& Distribution
This species was specialized to live at the higher
elevations of South Island’s alpine zone where it was common, while being rare in
eastern and lowland areas. It was widespread in upland herbfields and forests up to 2,000m
above sea level.
Physical
Attributes
Upland Moa were a relatively small and agile moa, not as
bulky as most members of Emeidae yet stockier and shorter-legged than members
of Dinornithidae. It was about the size of a Greater Rhea (Rhea americana) but was more heavily-built: standing up to 95cm (3.2ft)
at the hips and 160cm (5.3ft) to the top of the head, with a weight range of 17
to 40kg (37 to 90lbs). Unlike other known moa species, in which the females are
noticeably larger than the males, Upland Moa do not display any
obvious sexual dimorphism in regard to body size. The beak was particularly elongate
and pointed. The feet were proportionally the largest of any moa with
particularly long, strong toes and thick claws adapted for climbing up steep,
rocky slopes and for walking across snowy terrain.
Articulated skeletal remains with dried soft tissue have
been recovered from cave deposits. Among these, a complete head which included
the tongue, eyeballs, part of the neck, and trachea. Feather pits in the skin show
that the whole head up to the nostrils was covered in small feathers. A complete
foot is also known for this species. Unlike other known moa which had scaly
skin covering their lower legs, Upland Moa had feather pits extending down to
the bases of the toes indicating that the whole leg and much of the foot was
feathered. This is an adaptation seen among modern cold-adapted birds, such as ptarmigans
(Lagopus), which provides insulation
in deep snow. For the Upland Moa, this would have been ideal for the colder,
windier conditions encountered at higher elevations. Upland Moa feathers were
gray at the bases and deepened to a reddish-brown color toward the tips. Some
of these feathers had pale-colored tips which would have given the living bird
a speckled appearance similar to modern kiwis.
Desiccated type specimen of Upland Moa NHM A16 collected from Crown Range, Central Otago: A-B, Head and neck from left( A) and right( B) side. C-D, Right lower leg in medial (C) and lateral view (D). Figure 5 from Rawlence et al. 2013. |
Ecology
& Behavior
Evidence from coprolites and gizzard contents shows that
Upland Moa fed on a wide variety of alpine herbs and browsed from shrubs and
trees. The presence of parasites in the coprolites such as Trematotodes, Catatropis,
and Notocotylus (which typically afflict
aquatic or wading birds) suggest that Upland Moa also fed around the
margins of
alpine lakes where they would eat aquatic vegetation. Like modern
herbivores
which inhabit high-altitude environments, Upland Moa would have engaged
in altitudinal
migrations in response to snowfall and food availability: during the
autumn and
winter months they would move to lowland areas where food was more
accessible, returning to their upland feeding grounds during spring and
summer.
Predators of this species included the Haast’s Eagle (Harpagornis moorei) and the Eyles’ Harrier (Circus eylesi).
Upland Moa eggs are estimated to be about 162x111mm in size and
were greenish-blue in color, unlike other moa which seem to have had
white-shelled eggs. Newly-hatched chicks were able to move from the nest soon
after hatching and studies of cortical bone growth show that Upland Moa took
about 5 years to reach their full adult size. The fact that this species
exhibited minimal dimorphism suggests that ecological segregation among sexes
was limited, implying that Upland Moa were potentially more gregarious than
other moa species: modern herbivores which occur in mixed-sex herds display
minimal dimorphism in body size and overall appearance. The best modern
analogue for reconstructing Upland Moa social behavior may be the South Island
Takahe (Porphyrio hochstetteri), a flightless bird which forms family groups consisting of a monogamous breeding pair and their
offspring.
Upland Moa are rarely found in archaeological sites,
suggesting that they may not have been hunted as heavily as their lowland
relatives. This could, in part, be due to the colder and less habitable alpine
environments in which they lived: most Maori settlements were established at
lower elevations. Upland Moa were therefore most likely to have been hunted by
humans when they occupied lowland areas during certain times of the year. Habitat
alteration may have been the primary cause of this species’ decline. It has
been suggested that Upland Moa may have outlived other moa by as much as 100
years before they finally became extinct.
References
& Further Reading
Attard MRG, Wilson LAB, Worthy TH, Scofield P, Johnston P,
Parr WCH, Wroe S (2016). "Moa diet fits the bill: virtual reconstruction
incorporating mummified remains and prediction of biomechanical performance in
avian giants". Proceedings of the Royal Society of London B 283: 20152043
<Full
Article>
Rawlence NJ, Wood JR, Scofield RP, Fraser C, Tennyson AJD
(2013). "Soft-tissue specimens from pre-European extinct birds of New
Zealand". Journal of the Royal Society of New Zealand
DOI:10.1080/03036758.2012.704878 <Full
Article>
Wood JR, Wilmshurst JM, Rawlence NJ, Bonner KI, Worthy TH, Kinswlla
JM, Cooper A (2013). “A megafauna’s microfauna: gastrointestinal parasites of
New Zealand’s extinct moa (Aves: Dinornithiformes)”. PLoS ONE 8(2): e57315
<Full Article>
Wood JR, Wilmshurst JM, Richardson SJ, Rawlence NJ, Wagstaff
SJ, Worthy TH, Cooper A (2013). "Resolving lost herbivore community
structure using coprolites of four sympatric moa species (Aves:
Dinornithiformes)". PNAS 110(42): 16910-16915 <Full
Article>
Rawlence NJ, Wood JR, Scofield RP, Fraser C, Tennyson AJD
(2013). "Soft-tissue specimens from pre-European extinct birds of New
Zealand". Journal of the Royal Society of New Zealand
DOI:10.1080/03036758.2012.704878 <Full
Article>
Rawlence NJ, Wood JR, Armstrong KN, Cooper A. (2009).
"DNA content and distribution in ancient feathers and potential to
reconstruct the plumage of extinct avian taxa". Proceedings of the Royal
Society B 7(1672): 3395-3402 <Full
Article>
Gill BJ (2007). "Eggshell characteristics of moa eggs
(Aves: Dinornithiformes)". Journal of the Royal Society of New Zealand 37:
139-150 <Full
Article>
Turvey ST, Green OR, Holdaway RH (2005). "Cortical
growth marks reveal extended juvenile development in New Zealand moa".
Nature Letter 435 doi:10.1038/nature03635 : 940-944
<Abstract>
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