Moa

What did the giant eagle look like?

The most commonly seen resonstuction of Harpagornis, attacking adult moa, with plumage like an Australian wedge-tailed eagle. Pic: John Megahan / Wikipedia

The most commonly seen resonstuction of Harpagornis, attacking adult moa, with plumage like an Australian wedge-tailed eagle. Pic: John Megahan / Wikipedia

New Zealand was once home to the largest eagle in the world, Harpagornis moorei, often known as Haast’s eagle. I’m not a fan of that name: Julius von Haast was the Director of the Canterbury Museum and the first to scientifically describe the eagle, from bones collected from a North Canterbury swamp, in 1871. But getting an eagle named after yourself seems a trifle vain, so I prefer to call it the New Zealand eagle or the giant eagle, both of which are more descriptive.

Harpagornis is a marvellous name: “grappling-hook bird”, for its enormous clawed feet. What its Māori name was we’re not sure: pouakai and hokioi have both been recorded, but by the time written transcripts were being made the eagle had been extinct for centuries and had entered the realm of legend.

Wedge-tailed eagle (Aquila audax). The largest eagle in Australia, and capable of taking down a kangaroo, the wedge-tail has a typical eagle skull and head feathers, relatively short compared to a New Zealand eagle. Photo: Sam Schmidt / Flickr

Wedge-tailed eagle (Aquila audax). The largest eagle in Australia, and capable of taking down a kangaroo, the wedge-tail has a typical eagle skull and head feathers, relatively short compared to a New Zealand eagle. Photo: Sam Schmidt / Flickr

Recent examination of its DNA shows that the New Zealand eagle was most closely related to the Australian little eagle (Hieraaetus morphnoides), the smallest eagle on that continent. Its ancestors were blown to New Zealand and increased in size tenfold within a million years, an extraordinarily-rapid increase. Giant eagles weighed about 10kg in males and 14kg in females, nearly half as large again as the largest eagles alive today. They were big enough to kill adult moa—we’ve found the claw marks in moa pelvic bones. And they would have been very capable of killing humans too, which is probably why they were wiped out quite quickly, along with moa, soon after Polynesians arrived in New Zealand.

One account of the eagle, collected by Sir George Grey from a Ngāti Apa elder around 1850, describes it as living in the mountains, having red, black, and white feathers with a red crest, and being as big as a moa. The problem with this account is that giant eagles never, as far as we know, lived anywhere near Ngāti Apa in the Whanganui or Manawatu area. All the fossils we’ve found are from the eastern South Island and Southern Alps. So this centuries-old tradition is unlikely to be based on eye-witness accounts.

3. attenboroughOlder reconstructions of the giant eagle, based on this 19th century description, show it with lurid red plumage and a pointed crest. Its closest relative, the little eagle, is a rather more inconspicuous rusty brown. Most recent depictions give it the brown plumage of an Australian wedge-tailed eagle. Almost none of the reconstructions, however, get the head right: the giant eagle had an extraordinarily long skull, half as long again as you’d expect from a bird its size. The recent David Attenborough documentary set inside the Natural History Museum included a computer-animated Harpagornis, but it was really just a scaled-up golden eagle, with long narrow wings and a too-short skull.

(Attenborough was rather guilty of exaggeration when he described the eagle, in breathless voice-over, as having “a beak the size of a butcher’s cleaver”. Its beak is actually about 7 cm long, the size of my little finger or a paring knife.)

1. eaglevulture-sketchThe giant eagle’s extremely long bill, with small bony flaps protecting the nostrils, is actually rather like that of some species of Old World vultures. A vulture’s elongated bill is an adaptation for sticking its head inside the messy carcasses of animals much larger than itself. Most eagles don’t need such bills, because they’re feeding on relatively small prey. But giant eagles were killing moa 15 times their size, so their feeding would have been similarly messy. Not only did they have the elongated beaks of vultures, they perhaps had the short head feathers or even bald heads of them as well.

Griffon vulture (Gyps fulvus) have shorter, finer feathers on their head and neck (sometimes bald) and protected nostrils to prevent clogging. Photo: mhx / Flickr

Griffon vulture (Gyps fulvus) have shorter, finer feathers on their head and neck (sometimes bald) and protected nostrils to prevent clogging. Photo: mhx / Flickr

Ornithologists who study the New Zealand eagle get defensive when you suggest it may have had a head like a vulture. For decades, Harpagornis was victim of a terrible slander: its short wings supposedly meant it was on its way to becoming flightless, and it thus must have spent most of its time on the ground scavenging moa carcasses. In fact, short wings are a characteristic of forest eagles that need to maneouver around trees, not soar for long distances. And the discovery of claw marks on moa bones show that Harpagornis was indeed killing its own prey. But it took quite some time to dislodge its reputation as a scavenger, and a vulture-like reconstruction would hardly help.

Whether the New Zealand eagle had a bare head, or indeed a fancy red crest, is ultimately something we can’t determine from the few remaining bones. Māori rock art depictions of eagles are too stylised to help. Nobody has seen one for 500 years. Perhaps one day a mummified skull with feathers will turn up, as has happened with moa. But ultimately we have to make our own estimate of what’s probable, and rexognise that all depictions of a long-extinct creature, however convincing, are mostly well-informed guesses.

Dr Mike Dickison is Curator of Natural History at the Whanganui Regional Museum.

Whanganui Live!

Whanganui

In case you missed it on Saturday morning, the Director and the Curator of Natural History were interviewed by Kim Hill on Radio Live.  Kim Hill hosts the regular Saturday Morning programme and on 15th November visited Whanganui to air her show live from the Royal Opera house.  This was part if the ‘Smart21’ initiative which focuses on regional centres.

Listen to the interview with Dr Eric Dorfman, Director of the Whanganui Regional Museum, here as he talks about the job, his professional history, and the wonderful town he now lives in.

And listen to Mike Dickison, Curator of Natural History, here as he discusses the Museum’s amazing collection of Moa bones and taonga, the illicit trade of bones around the world, and his Wiki Wednesday project.

A Treasure Trove of Moa in Whanganui

Last week the Moa Gallery opened at the Whanganui Regional Museum in Stage I of a visible-storage project that sees the entire moa bone collection out of boxes in the basement to where people can see it, both in display cases and on the internet. But why is the moa collection so important? Why put it all on display?

North Island giant moa (Dinornis novaezealandiae)

North Island giant moa (Dinornis novaezealandiae)

Whanganui has been known for its moa bones since the earliest days of European settlement. As far back as the 1850s Anglican missionary Richard Taylor collected enormous bones from old pa sites and sent them to the eminent zoologist Professor Richard Owen in England. Owen was the first scientist to recognise that these bones could only be from a giant flightless bird, and coined the name Dinornis for them; a “terrible bird” in the same way a dinosaur was a “terrible lizard”.

Moa bones are found throughout the country, and collecting them was a popular hobby from the 19th century onward, so most museums in New Zealand have a moa collection. You can find the bones in caves from birds that wandered in, or fell down sinkholes; in dunes, where the shifting sand covered and protected their skeletons; or in swamps, where moa were trapped and sank into the mire, accumulating in huge numbers over the centuries.

The 1937 excavation at Todd’s Hole

The 1937 excavation at Todd’s Hole

As more of the pool was extracted, excavation continued as walls were built to hold back the liquid mud

As more of the pool was extracted, excavation continued as walls were built to hold back the liquid mud

One such moa death trap was near Ūpokongaro, up the Makirikiri Valley, in a swampy pool named Todd’s Hole on the Todd Family Farm. Beneath a thin crust of soil was a funnel of liquid mud full of moa bones, plus a few more from farm stock that had wandered in more recently. At first the bones could be just yanked out with an iron claw, but when the vast size of the deposit became clear, representatives from the Museum, with a £1200 excavation budget, began a proper excavation. Over 1937 and 1938 a crane, bucket and sluice were built, hundreds of cubic yards of mud sorted through by hand and about 2,000 moa bones extracted, cleaned and sorted.

Back at the Museum, the Curator George Shepherd began assembling skeletons from the pile of bones, putting together 10 in all. In those days moa classification was not well understood and many species were thought to be represented in the find, some from just a single bone.

Today with the help of DNA we can put the bones from Makirikiri into just three species: Mantell’s moa, a small species found around forest edges and wetlands; the bush moa, another small slender species that lived in the forest and seems to have been the most common kind of moa in the area; and the North Island giant moa, with gigantic females 1.5 m at the shoulder and weighing perhaps 200 kg, with males only half that size.

Photo of the Makirikiri Moa skeletons in the new Museum wing 1968. They’ve since been reassembled into positions more like those of a living moa.

Photo of the Makirikiri Moa skeletons in the new Museum wing 1968. They’ve since been reassembled into positions more like those of a living moa.

The skeletons were put on display in the Museum and the rest of the bones put in storage until they were re-examined in the late 1980s by moa expert Trevor Worthy. He was the first to recognise that the moa collection from Whanganui was of international importance. Although other large moa deposits had been discovered, especially in the South Island, most of those bones had been sent around the world, traded, lost, or destroyed. The Whanganui collection is one of the most important in the world because it has stayed almost completely intact, which lets scientists study an entire community of moa trapped in the swamp over thousands of years: their age, growth rate, size and male/female ratio.

These bony rings support the trachea, or windpipe, of a moa and are sometimes found in a pile in the middle of a very well-preserved skeleton.

These bony rings support the trachea, or windpipe, of a moa and are sometimes found in a pile in the middle of a very well-preserved skeleton.

The moa species that ate leaves and twigs would also swallow small stones, known as gastroliths or gizzard stones, to help grind up their food, in the same way chickens swallow pebbles and grit. Sometimes one or two kilograms of smooth stones can be found in a pile in a sand dune long after the rest of the moa skeleton has crumbled away.

The moa species that ate leaves and twigs would also swallow small stones, known as gastroliths or gizzard stones, to help grind up their food. Sometimes one or two kilograms of smooth stones can be found.

The goal of the Museum is to make this collection accessible by putting it all on exhibition and also by photographing, registering, and 3D-scanning the bones so everyone in the world can see them, not just people able to visit Whanganui. The whole process will be happening in the gallery itself, where visitors can watch and ask questions. We’re hoping that our moa collection will put Whanganui on the map, not only for moa biologists but for anyone interested in these amazing giant extinct birds.

 

Dr Mike Dickison is the Curator of Natural History at the Whanganui Regional Museum.

Reviving the Moa

Recently Labour MP Trevor Mallard, in a breakfast meeting with Wainuiomata business owners, suggested moa might roam the hills again in 50 or 100 years. He was widely mocked by politicians and pundits, but could he be onto something? How difficult would it be to resurrect the moa?
Ever since Jurassic Park brought back dinosaurs the idea of de-extinction has gripped our imagination, but the science has yet to live up to the hype. Geneticists have cloned a few animals and moved DNA around in the lab, but no species has returned from the dead yet. To revive an extinct animal, we need at least three things: all of its DNA, some way of getting that DNA into a living egg, and a mother for the egg that could incubate it or bring it to term.

In the early days on moa DNA research, chunks of bone were drilled out of museum specimens, ground up, and the DNA extracted. This revolutionised our understanding of the moa family tree, but the only a tiny percentage of the genome was recovered, and it was heavily contaminated with the DNA of microbes and even people who’d handled the bones.

In the early days on moa DNA research, chunks of bone were drilled out of museum specimens, ground up, and the DNA extracted. This revolutionised our understanding of the moa family tree, but the only a tiny percentage of the genome was recovered, and it was heavily contaminated with the DNA of microbes and even people who’d handled the bones.

The first step might be the easiest with moa. The DNA we’ve recovered from moa bones and eggs is in tiny fragments, most of it is missing, and it’s contaminated by microbes, but technological advances over the last 20 years have made us better at figuring out where the fragments might fit together. We haven’t figured out the entire moa genome yet, though we’re getting closer; it’s been successfully done for Neanderthals and mammoths. This is all on computers but we don’t know how to assemble the actual fragments like a giant jigsaw yet. Even if we did, building chromosomes out of the DNA would be very tricky. Nevertheless, these problems are ones we may well solve.

 

Recently researchers have discovered that moa DNA is preserved much better on eggshell than in bones; the pores of eggs protect it from the elements and contamination by bacteria. DNA from the inside of the shell is of both male and female chicks, but from the outside is only from males.

Recently researchers have discovered that moa DNA is preserved much better on eggshell than in bones; the pores of eggs protect it from the elements and contamination by bacteria. DNA from the inside of the shell is of both male and female chicks, but from the outside is only from males.

The second step is harder. A mammal’s egg can be extracted, its DNA replaced, and the egg coaxed into dividing again until it’s stable enough to implant back into the womb; this is how cloning works. The problem with bird eggs is they have a hard shell, and puncturing this, taking out an embryo, and reintroducing it after it’s been dividing for many generations is in the Too Hard basket at the moment. We can’t even clone chickens yet with a multi-billion-dollar poultry industry backing researchers. Extinct mammals, therefore, are likely to be revived well before we get around to birds.

 

 

Uncovered in 1931 during gravel excavation near Tokomaru, this egg of Anomalopteryx didiformis, the Little Bush Moa, is one of the six most-complete moa eggs in the world. Because it’s almost the same size as an ostrich’s, it represents the largest moa species we would be able to hatch from the egg of a living bird.

This egg of Anomalopteryx didiformis, the Little Bush Moa, is almost the same size as an ostrich’s egg and represents the largest moa species we would be able to hatch from the egg of a living bird.

A final problem with resurrecting moa is which egg would we use? Giant moa had eggs 24 cm long, much bigger than even an ostrich (the largest egg available), so there’s no living species that could hatch a giant moa chick. Some of the small moa species had ostrich-sized eggs (there is one in the Whanganui Regional Museum) but there’s a second problem: ostriches are only distant relatives of moa, no more closely related than horses are to cows. Transplanting the DNA of one into the embryo of the other is an insurmountable problem, at least at the moment.
So reviving moa would be very difficult, but there are other candidates that seem much more likely. Mammoths, for example, will almost certainly be resurrected before moa are. Mammoth cells have been snap-frozen in relatively good condition, so scientists have been able to sequence their genome. They have close living relatives; woolly mammoths are actually more closely related to Indian elephants than African elephants are. And the technology for cloning mammals is far more advanced than for birds. So in theory it’s certainly possible that one day an elephant will give birth to a mammoth calf.

 
But when? It might be 50 years before mammoth cloning is a reality, and moa would take even longer. By then, what state will the Siberian tundra be in? Will the mammoths have to live out their lives in zoos? There are big ethical questions about bringing back an animal with no habitat, at great expense, when other species are dying out for want of conservation dollars.
New Zealand forests, by contrast, evolved to deal with moa browsing. We could even see moa as an essential part of our forest ecology, missing for centuries, replaced by destructive mammals like deer and pigs. Luckily, we’ve spent decades perfecting ways to wipe out introduced pests and restore damaged forests; in 50 years, if we put our minds to it, we could have prime moa habitat ready to go when the technology catches up. Perhaps our grandchildren will get to see moa in the bush again.
 
Dr Mike Dickison is the Curator of Natural History at Whanganui Regional Museum and did his PhD research on the evolution of giant flightless birds.