By Nic Rawlence 15/11/2021

The scientists shield their eyes from the howling wind and flying sand as they carefully uncover the precious skeleton. If it wasn’t for the absence of giant sandworms, this could have been a scene straight out of Dune.

Alex Verry and Matt Schmidt are on Rakiura Stewart Island at West Ruggedy Beach excavating a significant taonga, a moa skeleton. Surrounding them are high, steep-sided golden sand dunes draped over granite tors that stick up out of the dunes like the emergent peaks of buried mountains. Just over the water, tantalizingly close, is the kākāpō stronghold of Whenua Hou Codfish Island.

Buried taonga: In a scene from Dune, Matt and Alex uncovered the Rakiura moa (foreground) that had been lost to the mists of time. Photo by Alex Verry.

The partial moa is resting in a natural granite bowl, which no doubt protected it for hundreds of years from being completely eroded away. Amazingly, underneath the skeleton were gizzard stones, used by the moa to grind up plant matter, and a dark brown organic-rich sand, stained by the rotting flesh and the moa’s last meal. Crucially, there were no cut marks on the bones to suggest butchery, nor any associated cultural material. This all screamed only one thing, something nearly as rare as moa’s teeth on Rakiura, a natural moa that died where it lay!

One of the biggest mysteries in reconstructing prehistoric Aotearoa New Zealand is whether moa naturally occurred on Rakiura, separated from the southern South Island by the shallow and often tempestuous Foveaux Strait. Moa bones do occur on the island but the vast majority are found in archaeological middens. These prehistoric rubbish dumps are dominated by leg bones and small pieces of industrial moa bone used to make tools like fishing hooks. The majority of the rare partial moa skeletons (even some with gizzard stones) that have been found on Rakiura either have butchery marks or stone tools associated with them. Only one partial moa skeleton has been found from pre-human times.

These observations have led some archaeologists and palaeontologists to suggest that moa didn’t naturally occur on Rakiura at the time of Polynesian colonization in the late 13th Century, despite the fact the island was joined to the mainland at the height of the last Ice Age about 20,000 years ago and moa could have walked to Rakiura. Instead, these scientists thought that dead moa were transported to the island by early Māori as food, yet seemingly didn’t entertain the idea the feathered giants were from in situ populations.

Just a few weeks before our expedition to the island, I’d received a call from Te Papa Atawai Department of Conservation archaeologist Matt Schmidt about a new moa find on the island. Did I want to come and help excavate it? Still recovering from a broken and dislocated elbow sustained on another fossil hunting trip that summer with Ngāti Kuri, my PhD student Alex jumped at the chance to go, like a kid being given the biggest lollypop he’s ever seen. In partnership with Murihiku Ngāi Tahu, an expedition was launched to rescue the moa before it was lost to the mists of time or worse still, was illegally pillaged and sold at auction.

Bringing ghosts to life: Ancient DNA showed South Island giant moa once called Rakiura home. Artwork by Paul Martinson © Te Papa CC BY-NC-ND 4.0.

What Alex and Matt found that day comprised a fair chunk of the skeleton including ribs, vertebra, the pelvis, and both thigh (femora) and shin (tibiotarsi) bones, in various states of preservation. The only things missing were the head, neck, and feet (tarsometatarsi and phalanges), which were probably hanging over the edge of the granite bowl and subsequently eroded or blown away.

Back in our lab after a brief chopper ride (the only time this moa has flown in its life), ancient DNA and morphological analysis of this precious taonga revealed that it was a sub-adult South Island giant moa (Dinornis robustus). Radiocarbon dating showed our moa was walking around Rakiura during the late 14th Century, a mere 100 years after Polynesians arrived on the island.

So if moa naturally occurred on Rakiura, why are their remains so rare? They could have occurred at low population densities as has been suggested. Part of the answer also concerns what happens after an animal dies, so-called taphonomy. Most of the subfossil bones from the island are found in sand dunes, dominated by the ghostly, bleached-white remains of seabirds. Forest birds, of which Rakiura has many, are almost non-existent, which started another booming feathered debate. Did kākāpō occur naturally on Rakiura or were they dropped off by Māori or Europeans sometime in the last 500 years? Ancient DNA from historical museum skins suggests kākāpō have been on the island since at least the end of the last Ice Age (well before humans were even on the scene), when sea levels started to rise, cutting off Rakiura from the mainland. If you were unlucky enough to die in the depths of Rakiura’s forests, you aren’t going to be preserved for scientists to find in another time.

If we were going to find a natural moa, then it’s not surprising it was the cosmopolitan South Island giant moa, which can live in dune environments. It’s possible other moa found on Rakiura in archaeological deposits, like the heavy-footed moa (Pachyornis elephantopus) and eastern moa (Emeus crassus), occurred there also – these species certainly formed part of the moa dune assemblage on the mainland. Only time and more discoveries will tell.

Gifting back Aotearoa’s lost stories: Discoveries such as these can shed light on a prehistoric world. The piece of bone cut out of the Rakiura moa shin (tibiotarsus) allowed ancient DNA analysis and radiocarbon dating. Photo by Guy Frederick.

The Rakiura moa represents a lost story, one we have been able to decipher and give back to manawhenua and Aotearoa. The alternative that these taonga, with their rich story to tell, could have been illegally collected and sold is too much to bear – the bones were found only 20 metres from the Great Walk track! The proposed ban on the sale of moa bones (and those of other extinct New Zealand species) will protect our stories and allow scientists in partnership with iwi to tell them. Private individuals are stealing these taonga from national parks, caves, and protected archaeological sites, and selling them to the highest bidder at auction houses and websites like TradeMe. The provenance of these traded bones is sketchy at best, but for those in the know, like us moa scientists who have spent years studying their remains, we can tell the majority of these auctions are of illegally collected material – the way a bone looks and its colour tells us a lot about its history. A moa with two left feet being sold as a complete skeleton instead tells a more sinister tale of pillaging of fossil sites. Ban the sale of moa bones and you take away the reason for the majority of people to collect them.

The discovery of a rare natural moa on Rakiura tells us so much of the island and its prehistoric record is yet to be explored. I for one am looking forward to what we find next, and who knows, we might just solve a giant feathered mystery along the way.