Hidden Treasures: Solving the mysteries of the moa at Canterbury Museum

Thursday, 24 December 2020

Professor Paul Scofield explains why Canterbury Museum's collection isn't just 'dusty old bones'.

Just 1 per cent of Canterbury Museum's collection is on display at any one time. As part of a special series, reporter LEE KENNY and visual journalist JOHN KIRK-ANDERSON went behind the scenes to discover the hidden treasures held in its vast archives.

It must have been an incredible sight, a group of moa migrating across the prehistoric landscape – but did you know their ancestors flew to New Zealand?

It was once thought the giant birds were already flightless when the continental crust around the New Zealand separated from Gondwana 80 million years ago.

But an analysis of moa bones held at Canterbury Museum revealed they flew here, before evolving to become bipedal.

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Dr Paul Scofield, senior curator at Canterbury Museum, says recent discoveries have changed what we know about moa.

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With 30,000 moa bones from 8000 individuals, the Christchurch collection is the largest in the world.

Some of the museum's earliest moa bones were unearthed in North Canterbury in the 1860s.

One of the many moa skulls held in the archives at Canterbury Museum.

But far from just being preserved for posterity, the remains are being used to rethink what we know about the extinct birds.

Dr Paul Scofield is a senior curator of natural history at Canterbury Museum and is responsible for building and researching the vertebrate and geological collections.

Recent studies of the bones have provided a fascinating insight into the origin of the species.

“Using DNA extracted from the blood vessels in the bones, we can compare it to the DNA with living and extinct relatives of moa,” Scofield says.

A large percentage of Canterbury Museum's vast collection has never been seen by the public.

“This isn't just a collection of dusty, old bones, it's in fact incredibly useful for understanding the science of moa.”

Moa may have originated in South America, as its nearest living relative is the tinamou, which is found in the forests of Ecuador and Peru.

“Up until about 20 years ago it was commonly believed that moa and kiwi were probably each other's closest relatives. We now know that is incorrect,” Scofield says.

“When they arrived in New Zealand, the relatives of moa were quite a lot smaller and were able to fly. It became much larger and flightless in a comparatively short space of evolutionary time.

“That's really quite a radical change in our understanding of the evolution of these species and that's only possible because of these collections, which are held in perpetuity for both the people of New Zealand and our understanding of the science of the species.”

A moa bone that was recovered 1891. Other items in the collection were discovered in the 1860s.

Moa have been extinct for 500 to 600 years. It is not known what led to their demise, but Scofield says it was probably a combination of predation (being hunted for food) and human disruption to their ecosystems.

“It was a bit of a perfect storm of bad conditions. It was just too much, too quickly,” he says.

“There are other possibilities. The diseases that chickens bring have been shown elsewhere in the world to have wiped out species. That is controversial because there's no direct evidence that Māori introduced chickens to New Zealand.”

It is impossible to know exactly how many moa there were when humans first arrived in New Zealand and Scofield says the science of estimating population sizes from DNA is also “a little bit controversial”.

“Some people say there weren't very many and that's why they became extinct, some people say there were a lot.

“For these large species, they would have numbered in the low tens of thousands on each island.”

The southern South Island giant moa took up to nine years to reach full maturity and by drilling into the bones, researchers can determine an individual’s age – similar to how a tree can be aged by counting the rings inside the trunk.

“We are able to use techniques such as core-drilling to work out how old individuals were, or at least how long it took them to reach full maturity.

“They have got little ‘tree-rings’ in the bone, which show you how many winters it took to reach adult size.”

DNA can also indicate if a bird was male or female and even which ones were related.

Scofield says future studies will only further improve our understanding of moa.

“We don't know anything about their direct behaviour, but from the study of these bones and using DNA techniques, we're able to tease out specific information about the life history of these amazing birds.”

The items listed in this article are not currently on public display.