DNA

The Mysterious Adzebill

New Zealand was once home to many flightless birds. Some, like the moa, are well-known, but others, like our flightless ducks, geese, and owlet-nightjar, are familiar mostly to palaeontologists. One bird that deserves to be better known is the mysterious adzebill.

1. Adzebill Martinson

A North Island adzebill (Aptornis otidiformis) eyes up a tuatara in a 2005 painting by Paul Martinson.
Photo: Te Papa / CC-BY-NC-ND

There were two species of adzebills, Aptornis otidiformis in the North Island and Aptornis defossor in the South. Both were huge. When their bones were first discovered, they were mistaken for a small moa. Fully-grown birds would have weighed perhaps 20 kg, larger than a swan or pelican.

Adzebills had massive heads with heavy down-curved beaks. The beaks tapered to a point, and Dr Richard Holdaway, who coined the name “adzebill”, once confessed to me that “pick-bill” would have been more accurate. The robust vertebrae in their neck would have anchored strong muscles and allowed them to deliver a powerful blow.

These birds also had massive feet, with strong tendons, that would have made them good at digging. For some time biologists debated what they ate. Did they dig up roots, pluck leaves or break apart rotten logs? Their beak wasn’t hooked like a bird of prey.

A technique called stable isotope analysis which lets us analyse animals from the composition of bone – you are what you eat – revealed that adzebills were carnivores. We can imagine them tearing open trees for huhu grubs, plucking lizards or baby birds off the forest floor, digging up giant earthworms, and excavating tuatara, or even nesting seabirds, out of their burrows.

A second mystery was what adzebills were, exactly. They didn’t resemble rails like the weka or takahē, and for some time were put in their very own family. Some ornithologists thought their closest relative was the flightless kagu of New Caledonia. Others thought it belonged with chicken-like South American birds called trumpeters. The debate continued fruitlessly for decades.

Alex Boast is a PhD candidate at the University of Auckland, working on ancient DNA. Improved techniques now allow us to recover and examine fragments of DNA from bones and eggshell of extinct birds, not enough for Jurassic Park cloning, but enough to construct a family tree and determine their nearest relatives. Alex analysed adzebill DNA and compared them to numerous other birds, and the results suggest that adzebills are not kagus, or trumpeters. They are flufftails.

2. Flufftail Keugelmans

The white-spotted flufftail (Sarothrura pulchra), painted by John Keulemans in 1894. This delicate little bird seems to be the adzebill’s closest living relative.
Ref: Wikimedia Commons

Flufftails (nine species in the genus Sarothrura) are secretive ground-dwelling birds about the size of a starling, rusty brown and spotted. They do indeed have fluffy tails. What’s unusual is that flufftails are all found in Africa, and on the island of Madagascar, nowhere near New Zealand.

Africa and New Zealand were once connected as part of the supercontinent Gondwana of course, and fossils tell us that adzebills have been here for millions of years, plenty of time for their ancestors to get here and evolve into a giant flightless predator. Intriguingly, the kiwi seems to have done the same thing. Its closest relative is another African species, the elephant bird of Madagascar. The difference is, while one flightless bird survived the arrival of human beings and became the symbol of New Zealand, the other was wiped out. The not-so-mysterious adzebill is now mostly forgotten.

 

Dr Mike Dickison is curator of natural history at the Whanganui Regional Museum.

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Discovering new species

When a new species of plant or animal is discovered it’s a big news story, but the secret amongst biologists is that it’s actually easy to find a new species. It’s hard to convey to people just how many species remain to be discovered, and how few people there are left looking for them.

Undiscovered jumpers: There are over 50 species of cave wētā, or tokoriro, in New Zealand, which, despite their name, live mostly in the forest. So many new species are being discovered that there is a backlog waiting for the few entomologists who study wētā to find the time to describe and name them. Creative Commons BY-NC, Jon Sullivan / Flickr

Undiscovered jumpers: There are over 50 species of cave wētā, or tokoriro, in New Zealand, which, despite their name, live mostly in the forest. So many new species are being discovered that there is a backlog waiting for the few entomologists who study wētā to find the time to describe and name them.
Creative Commons BY-NC, Jon Sullivan / Flickr

There are probably undescribed species living in your backyard. Entomologist Willy Kuschel spent 15 years collecting beetles in the Auckland suburb of Lynfield. He found 982 species of beetle, far more than anyone would have suspected could be living 10 kilometres from the central city. Amazingly, 150 of those beetles were new to science. Nobody had noticed them because nobody had looked.

There are probably species to be discovered in Springvale and Aramoho, but if I wanted to find one I’d start at Bushy Park, one of the last remnants of lowland forest in this part of the country. Bushy Park has never had biologists do a comprehensive survey of its insects, snails, and spiders, so we have no idea what’s there. Collecting a scoop of leaf litter from the forest floor and picking through it might well reveal species surviving there and nowhere else.

The stick that moves: A new species of stick insect found only on the Poor Knights Islands was recently named Clitarchus rakauwhakanekeneke, in conjunction with local iwi Ngāti Kuri. Its Māori name means “the stick that moves”. Thomas Buckley / Landcare Research

The stick that moves: A new species of stick insect found only on the Poor Knights Islands was recently named Clitarchus rakauwhakanekeneke, in conjunction with local iwi Ngāti Kuri. Its Māori name means “the stick that moves”.
Thomas Buckley / Landcare Research

The scientists who do this sort of survey and name new species are called taxonomists and their work is the foundation of all conservation policy and ecological research; you have to be able to list and name the living things in an area before you can measure how they’re doing or develop a management plan. Taxonomic research has always been the mainstay of museums, which have large comparative collections. But museums all over the world have been cutting back, and New Zealand is no exception.

 

When I was a lad I was mad keen on lizards, and conventional wisdom was that we had a dozen or so species in New Zealand. Since we started looking closely at lizards and their DNA, it turns out there are actually about 100 species, but there are only a handful of scientists able to formally describe them and give them names. The most recent field guide to native lizards has to refer to fairly-widespread species with labels like “Genus B species 1”, because we don’t have enough taxonomists.

Thambotricha vates, a Latin name that translates as “wonder-haired prophet”, has been found by entomologists for the first time since 1996. This elusive moth has only been seen 15 times since it was described and named in 1922. Creative Commons BY-NC, XXXXXXXXXXX / Flickr

Thambotricha vates, a Latin name that translates as “wonder-haired prophet”, has been found by entomologists for the first time since 1996. This elusive moth has only been seen 15 times since it was described and named in 1922.
Creative Commons BY-NC, XXXXXXXXXXX / Flickr

Even after a species is described, we don’t know necessarily know anything about it. Recently a small moth, Thambotricha vates, was caught by Landcare entomologist Robert Hoare. It had last been seen in 1996 and only 15 specimens had been collected by scientists since it was first described in 1922. Because it’s found from Nelson to Katikati, it probably isn’t rare; we just don’t know its habitat. Although the media treated this rediscovery as a big story, it isn’t all that exceptional. There are over 1,700 species of moths in New Zealand, and some of our 10,000 insect species have almost certainly been seen just once, by the entomologist who described them.

 

In NZ there are many species of native earthworms, some of them gigantic. In all the gardens, parks, and farmland of NZ the earthworms are just a few introduced European species. Unfortunately we know very little about native earthworms; many have been found from deep in the subsoil, living in a single patch of native bush. Thirty species occur only on a single small island each, but 102 species are listed as “data deficient”. They could be widespread, or on the verge of extinction – we don’t know. And there are surely native earthworms still unknown to scientists, which might go extinct before they’ve even discovered.

A new species washed up on the beach: George Shepherd, Curator at the Whanganui Regional Museum in 1933, measuring the skull of the beaked whale that was eventually named Tasmacetus shepherdi in his honour. Whanganui Regional Museum Collection 1805.296.2

A new species washed up on the beach: George Shepherd, Curator at the Whanganui Regional Museum in 1933, measuring the skull of the beaked whale that was eventually named Tasmacetus shepherdi in his honour.
Whanganui Regional Museum Collection 1805.296.2

Not all new species are moths and worms. There are still discoveries to be made in the deep sea, even of large marine mammals. The Whanganui Regional Museum still has the skeleton of a beaked whale that washed up on the beach near Hāwera in 1933, and was collected by George Shepherd, the Curator at the time. He recognised it was unusual, and sure enough it turned out to be a new species. Shepherd’s beaked whale (Tasmacetus shepherdi) lives in deep water far from shore, in cold southern seas, so live animals have been seen only a handful of times. Most of what we know about them comes from stranded specimens.

 

New techniques can also help discover species that were hiding in plain sight. When the DNA of kiwi populations all over New Zealand was compared, the birds around Ōkarito on the West Coast turned out to be very different from other brown kiwi. Collectors in the 19th century had noticed this, and used the name rowi to distinguish them from other kiwi. The DNA evidence was enough to establish them as a new species, Apteryx rowi, numbering just a few hundred birds in one patch of forest. They now have their own captive breeding program.

Saving a subspecies: The Hector’s dolphin (Cephalorhynchus hectori) has North Island and South Island subspecies that can interbreed. The North Island form, or Maui dolphin, is in danger of extinction, but saving it shouldn’t be as high a priority as all the other actual endangered species in New Zealand. Creative Commons BY-NC, Earthrace Conservation / Flickr

Saving a subspecies: The Hector’s dolphin (Cephalorhynchus hectori) has North Island and South Island subspecies that can interbreed. The North Island form, or Maui dolphin, is in danger of extinction, but saving it shouldn’t be as high a priority as all the other actual endangered species in New Zealand.
Creative Commons BY-NC, Earthrace Conservation / Flickr

Without the attention of taxonomists the rowi might have quietly gone extinct while we were distracted by showier things like Maui dolphins (which are not actually a distinct species, just the Hector’s dolphins that happen to live in the North Island). The worst scenario is discovering much later, from museum specimens, that something collected a century ago is both a distinct species and no longer to be found in the wild. How many species have we already lost, species that we’ll never know about, because we didn’t notice them in time?

 

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

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.

The Passenger Pigeon

In the 1870s, passenger pigeons were still forming a “feathered river across the sky”, but by the end of the decade their numbers had crashed.  Smith Bennett, Wood engraving from original sketch

In the 1870s, passenger pigeons were still forming a “feathered river across the sky”, but by the end of the decade their numbers had crashed.
Smith Bennett, Wood engraving from original sketch

The passenger pigeon (Extopistes migratorius) was once the most abundant bird on Earth. Flocks of millions of birds darkened the skies of North America, and took days to pass overhead. When they descended on a forest they would strip it bare of nuts and acorns, break branches with their sheer numbers, and carpet the ground with droppings, which eyewitnesses said “fell like snow”. People firing randomly with shotguns or waving sticks would knock down dozens, to be packed and shipped east as cheap food. Yet, incredibly, by the end of the 19th century, the birds had almost disappeared.

Martha died on 1 September 1914, aged probably 29, in Cincinnati Zoo. She was the last survivor of a small flock that the zoo had been unsuccessfully trying to breed in captivity.

Martha was the last survivor of a small flock that the zoo had been unsuccessfully trying to breed in captivity.

This specimen was given to Samuel Drew, the founder of the Museum, by the German naturalist Otto Finsch in the late 19th century.

This specimen was given to Samuel Drew, the founder of the Museum, by the German naturalist Otto Finsch in the late 19th century.

The last passenger pigeon, named Martha, died in Cincinnati Zoo in 1914. Her body was immediately frozen in a block of ice and sent to the Smithsonian Institute. Other museums had been collecting specimens as the pigeons approached extinction; there are about 1500 in museum collections around the world, including three in the Whanganui Regional Museum. But it wasn’t collectors or even hunters that ultimately wiped out the passenger pigeon, although they were hunted in staggering quantities, but forest clearance. The birds relied on huge forests of nuts to maintain their enormous flocks, and they needed to breed in enormous communal colonies. Once enough forest had been cleared for agriculture, flocks dropped below a critical threshold for breeding, and during the 1870s the population crashed. Past this point, they were doomed as a species, though a few persisted into the 20th century.

 

 

These mounted male and female passenger pigeons show off the male’s pale cinnamon breast feathers. Whoever mounted these birds gave them yellow eyes, but those were red in life.

These mounted male and female passenger pigeons show off the male’s pale cinnamon breast feathers. Whoever mounted these birds gave them yellow eyes, but those were red in life.

John James Audubon, the French-American naturalist and artist, included this pair of passenger pigeons in his masterpiece Birds of America, published in a series between 1827 and 1838. He recalled seeing an enormous flock of several billion birds in 1813 that took three days to pass overhead.

John James Audubon, the French-American naturalist and artist, included this pair of passenger pigeons in his masterpiece Birds of America, published in a series between 1827 and 1838. He recalled seeing an enormous flock of several billion birds in 1813 that took three days to pass overhead.

Recently, researchers examining passenger pigeon DNA were surprised to find that despite their abundance the birds had quite low genetic diversity, suggesting that their population had only recently exploded when European settlers encountered them. The best explanation is that pigeon numbers went through periodic booms and busts, in response to regular fluctuations in the availability of nuts and acorns, which occasionally have super-abundant “mast” years. Pigeons had evolved to seek out heavy nut crops and rapidly increase their numbers to exploit them. When Native Americans were devastated by disease following colonisation, they stopped hunting pigeons and collecting nuts, and passenger pigeons quickly increased to enormous numbers. Their population was going through a natural downturn at exactly the time European forest clearance and hunting began to increase, and those combined forces were enough to push them into a death spiral.

To estimate pigeon genetic diversity for this study, the researchers needed DNA, which is hard to get from a species extinct for 100 years. They turned to museum specimens, and were able to take tissue scraped from the toe pads of passenger pigeon skins and use recently-developed technology to extract fragments of DNA and reconstruct long sequences of the bird’s genome. This ability to recover ancient DNA has made museum collections valuable in a new and unexpected way: from them we’ve learned that female moa were twice the size of males, that the kiwi and the Madagascar elephant bird are close relatives, and, now, why the passenger pigeon went extinct so rapidly. Even if they died over a century ago, museum specimens can, in a small way, live again.