Only New Zealand can create a species as lovably odd as the kiwi, which is essentially a mammal masquerading as a bird.
New Zealand’s location and isolation cultivated a unique collection of birds. But the same factors that make these birds so interesting also make them susceptible to extinction, as New Zealand is overwhelmed by an invasion of mammals.
Evolution is founded in gene mutation, when some random rung of an organism’s DNA ladder is altered. This genetic change, however minor it may seem, can have a huge impact on how the actual creature looks or acts. For example, you and me as humans differ from chimpanzees in only 1.2% of our genetic material. An incredibly small amount of difference, but it has made all the difference.
So evolution, at its core, is random due to the fickleness of genetic mutation. These tiny mutations either create an advantage for an organism or damage it, which could be the difference between the longevity of s creature or its ultimate demise. If the mutation creates an effective enough trait, that may lead to a new species someday.
This is where isolation becomes the driving force that amplifies the effects of mutation. Isolation can be in the form of being geographically stranded on an island or isolated in the form of a mutated group being unable to breed with its species. Whichever form of isolation evolution chooses, it eventually leads to speciation as one group of a species goes down a different evolutionary pathway than another group on a different island or a different mountaintop.
You are probably wondering about the relation between this abbreviated high school biology lecture and New Zealand’s wild birds (which is what you came here for), but isolation is the backbone to the evolution of New Zealand’s amazing wildlife. New Zealand’s isolation for millions of years has created a living laboratory of evolution that has cooked up some wild animals. Gecko’s give live birth here, insects become large enough to eat large carrots, and you are more likely to stumble upon a bird on the ground than see one soaring above your head. Only New Zealand could be home to a 10 foot-tall ostrich on steroids, the world’s only flightless parrots, and a bird with whiskers.
Sadly, many of these creatures are already gone or teetering on the edge of extinction. New Zealand’s extinction rate for birds is incredibly high at 34%. Species like the Chatham Island snipe, fairy tern and kaki have populations with less than 150 individuals. The evolutionary processes that molded New Zealand’s incredible birds have also contributed to their demise in today’s world.
The Antipodes
New Zealand owes a lot to its far-flung location. It is so remote, over 1,300 miles southeast of Australia resting about halfway between the equator and the South Pole, that it was one of the last places on earth to be settled by humans. The Polynesian ancestors of the Maori arrived to New Zealand in large, ocean-going canoes only around 850 years ago and dubbed it Aotearoa, “the land of the long white cloud.”
Early European explorers called New Zealand and nearby Australia the antipodes because of their existence on the opposite side of the globe from Europe. It’s not quite right, but it does sum up the otherworldly land and animals they found there.
This geographical isolation from the rest of the world was due to processes deep within the earth. New Zealand, along with the rest of the Southern Hemisphere, was once part of the supercontinent Gondwana. The most fateful moment in the evolutionary history of New Zealand is when it broke off from this massive landmass to do its own thing 85 million years ago. This breakup was caused by the phenomenon of plate tectonics, or the shifting and colliding of continental plates on the earth’s mantle. As the continental plates that formed Gondwana began to shift apart, New Zealand was essentially along for the ride, drifting farther and farther away from Australia. New Zealand’s islands are actually still drifting, with Christchurch in the South Island (on the Pacific plate) moving away from Auckland and the North Island (on the Australian plate) at about 4 meters every century.
New Zealand’s existence far from any other major landmass effectively cut it off from the rest of the planet, letting evolution run its course without outside interference. That all changed when the Maori hauled their canoes up onto the black sand beaches of New Zealand.
The tui is one of New Zealand’s more interesting-looking birds, sporting distinctive white tufts under their throat. The aggressive and noisy bird plays a key role in New Zealand forests as a pollinator and seed disperser. This picture was taken at the Kiwi Birdlife Park in Queenstown, New Zealand.
The Avian Ark
When New Zealand set out on its ‘continental drift’ odyssey, dinosaurs were its main inhabitants on land and large seagoing reptiles dominated the surrounding waters. Essentially missing from the drifting landmass were mammals, who were still toward the bottom of the biological pecking order during the Cretaceous Period. After non-avian dinosaurs and giant sea reptiles were wiped out following the last mass-extinction 65 million years ago, their evolutionary offspring, avian birds, took over a landmass unlike anywhere else on earth. It had no land-based mammals, save for three species of tiny bats.
This offered birds the incredible advantage of returning to the ground. With no land-based predators, wings began to become almost frivolous ornaments for birds who had nothing to fear on the ground. Even the native species of bats walked on the ground, using the elbows of their wings to scamper about. Evolutionarily speaking, the ability to fly is very energy intensive, and since there was nothing to eat you while on the ground, flying lost its evolutionary advantage. Many birds on the island have lost the ability to fly well, while many have even lost the ability to fly altogether.
Here are a few of the most interesting avian oddities cooked up in New Zealand’s wonky evolutionary lab:
A stuffed kakapo at Auckland’s War Memorial Museum.
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One prime example of complete flightlessness is the kakapo, a large nocturnal parrot that resides on the ground full-time. Besides being the only species of flightless parrot, the kakapo is also the world’s heaviest parrot at a hefty five to nine pounds. Without the presence of predators, the kakapo was able to pack on the pounds and lose the ability to fly. The wings are not quite vestigial, or functionless, as the stocky parrot uses them to balance while it ambles and climbs through the forest.
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Another remarkable bird from the “Land of the long white cloud” was the huia. The largest of the five wattlebird species native to New Zealand, this songbird had the most striking example of beak sexual dimorphism of all birds. Male and female huia have completely different beak structures, with the female sporting a longer, curved beak and the male possessing a shorter, heavier straight beak. Attached at the base of each of their beaks were bright, fleshy orange wattles that contrasted against the dark black of its feathers which would sheen green and blue when light danced on them. Like many of their fellow New Zealanders, the huia seemed to have been a reluctant flier, preferring to hop along low branches and the forest floor. Huias were reportedly the first birds to call in the morning, with each sex calling and responding with unique calls, answering one another during the day’s first light.
The two distinct beak shapes of the huia bird, the most extreme example of beak sexual dimorphism in all of birds.
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The most famous and strangest of all of New Zealand’s birds is the kiwi. The species is so beloved, it has become a national symbol. New Zealanders have proudly called themselves kiwis since 1917. The shaggy flightless national icon evolved from birds that flew to New Zealand millions of years ago. Like many other New Zealand birds, the absence of mammals not only allowed the kiwi’s ancestors to feel safe enough to leave the sky for the ground, but also offered many empty ecological niches that were filled by mammals elsewhere. Today there are five species of kiwis, all around the size of a chicken, with the aptly named little spotted kiwi and great spotted kiwi bookending the size spectrum.
The kiwi bird examines some kiwi fruit. Also known as Chinese gooseberry, the fruit is usually called kiwifruit in New Zealand to help Kiwis avoid confusion between the fruit and the kiwi bird.
Kiwis specifically are a great illustration of the evolutionary power of isolation. Although there are only five kiwi species today, over the last million years there have been at least 11 lineages of kiwis. The rapid evolution into different forms and possibly into distinct species is reminiscent of Darwin’s Galapagos finches who diversified when spreading to new islands with diverse food sources.
But instead of being isolated on different islands, the kiwis were isolated by glaciers throughout New Zealand, which have expanded and retracted numerous times over the last 800,000 years. Over this period of extreme cycles of glaciation, the kiwis diversified five times faster than usual according to a 2016 study. At that rate, they were diversifying faster than even the Galapagos finches!
Kiwis today are nocturnal, passing the day away sleeping in hollow logs and burrows. At night, kiwis forage for insects, berries and seeds along the forest floor with their impeccable sense of smell. They are, in fact, the only birds with nostrils on top of their long, slender beaks. At the base of their beak are cat-like whiskers that help them feel through the dark. In fact, the kiwi has many similar mammalian traits, including the lowest body temperature of any bird at a mammal-like 100 degrees Fahrenheit, well-developed hearing, and two ovaries (most birds have one).
While on the topic of ovaries, the kiwi’s egg is incredibly large compared to their body size, sometimes accounting for up to 20% of the females weight (the same as a 120-lb woman giving birth to a 24-lb baby)! A benefit of the egg being so large is that baby kiwis are very developed when they hatch, which is vital because by that point, the parents are gone.
A female kiwi and her massive egg at Auckland’s War Memorial Museum.
Lost in all the hubbub about moas and kiwis is the recently discovered Kumimanu biceae, the world’s second largest penguin ever. Living 55 million years ago, only 10 million years after the asteroid impact that wiped out the dinosaurs, this penguin was massive, packing 220 pounds into a 6 foot frame (the largest species today tops out at 4.3 feet tall). The name reflects its impressive size: Kumimanu is a combination of the Maori words for “monster” and “bird”.
Gigantism vs. Dwarfism – What Gives?
The birds of New Zealand are very strange today thanks to being isolated from mammals. But the mere fact of being isolated on an island kicks evolution into overdrive as populations are isolated by large swaths of water. Islands have the ability to create giant and dwarf-sized species, and one of the best examples of this occurred on New Zealand.
Moas were a collection of ostrich-like, flightless birds that included the tallest species of bird ever, which stood as tall as a basketball hoop and weighed around 550 pounds. The smallest of the nine confirmed species was about the size of a turkey, tiny compared to its immense brethren but still a large bird in its own right.
Although large moas, like the South Island giant moa, may have looked intimidating, they were chiefly grazers and browsers, eating fruit, seeds and grasses. They are also the only flightless bird to not have wing bones, which shrouds their arrival to New Zealand in mystery. Growth rings in leg bones have led researchers to believe moas grew at incredibly slow-rates, taking ten years to stretch into the trees.
But why were moas so much larger than similar species from the mainland, like ostriches and emus? Gigantism on islands has been a phenomenon observed since at least 1964 when biologist J. Bristol Foster made some interesting general observations while looking at mammals on North American islands. He concluded that small animals, like rodents, tended to grow larger on islands, and bigger animals like deer (and, in one case off of California, mammoths) tended to shrink on islands. This became known as the “island rule.”
But this rule is not so cut and dry, as one island may have giants of a species while the same animal is dwarfed on a nearby island. The particulars of what spurs gigantism or dwarfism on islands is still hazy, but we can look at the moa example to figure out why the bird became so giant on New Zealand.
Having the benefit of not being hunted on New Zealand promoted larger size, as well as the general rule that larger animals can exploit a wider range of resources, which leads to healthier individuals and healthier (and larger) offspring. Being so large also helped moas survive drought and famine because of their larger stores of energy and water. Ultimately, the circumstance in New Zealand was perfect for moas to become gigantic. On New Zealand there were no other large land animals after the demise of the dinosaurs, leaving the large herbivore ecological niche wide-open and moas evolved to fill it, eventually dwarfing flightless birds almost everywhere else.*
New Zealand’s mighty moas.
New Zealand’s most fearsome bird evolved to prey on these mammoth moas. The Haast eagle was the largest eagle ever and was equipped with talons as large as tiger claws. Both the Haast eagle and the moas had to deal with periods of glaciation over the last million years of New Zealand, and bigger body size probably helped them survive the cold.
Haast eagles were perfectly evolved to target even the largest moas on New Zealand’s island. It would dive down on top of the massive bird, knocking it down with its large feet before crushing its skull. Ancient Maori stories tell of giant birds called “pouakai”, which were probably Haast eagles. Terrifyingly, these stories tell of the giant birds sweeping in and taking the occasional child for dinner, which is no exaggeration when considering the size of these eagles.
*While the Southern Island giant moa was the world’s tallest bird, the heaviest bird was the elephant bird from the island of Madagascar. Elephant bird eggs are the only thing capable dwarfing a moa egg with a volume equal to over 150 chicken eggs!
The morepork is New Zealand’s only species of owl. It gets its name from its call, which actually sounds like the owl is asking for “more pork”. Although considered not threatened, small mammals like possums raid morepork nests to steal eggs. Picture taken at the Kiwi Birdlife Park in Queenstown, New Zealand.
The Mammalian Invasion Threatens to Topple the Avian Ark
Unfortunately, these two magnificent birds are extinct, disappearing a few hundred years after the arrival of humans. The moa was most certainly hunted to extinction by early settlers. A 2014 study of the bones from 281 moas found no DNA evidence for genetic decline before the arrival of humans, with the population looking remarkably healthy before the first Polynesians arrived. Moas were over hunted to extinction by the late 1600s. With the disappearance of its food sources, the Haast eagle faded into extinction with the moa, denying us the ability to see one of the most spectacular hunts in our planet’s history.
But for most species of New Zealand birds, the most dangerous thing about the arrival of humans was not the humans themselves but what they brought with them. For millions of years, New Zealand offered a safe haven for birds to evolve and adapt without the presence of mammals. The arrival of the Maori 850 years ago, followed by European settlement 600 years later, threw a wrench into the bird evolutionary eden by introducing a plethora of mammals that outcompeted and ate these marvelous birds. Sheep, elk and cattle were brought in to graze upon the fields that were once forests. Rabbits, rats and mice also found their way over, outcompeting smaller birds and eating their eggs.
Brushtail possums were brought across the Tasman Sea from Australia to jumpstart an ultimately fruitless fur trade in the 1850s. Today the possum population is at an astounding 30 million and the cute marsupials wreak havoc on native New Zealand forests, chewing through trees never adapted to such an efficient omnivore. Their presence causes trees hundreds, if not thousands, of years old to collapse. Like rats, they also outcompete native birds and eat their eggs.
Early attempts to solve the invasive mammal problem only exacerbated it. The weasel-like stoat was brought over to control the exploding rabbit population. The predator soon found the naive ground-dwelling birds to be much easier prey than rabbits, which led to a spike in stoat populations and little effect on the rabbit population. Similar to Australia, the cats and foxes brought over as pets and for sport have proved to be the most damaging, as the small, flightless birds are the optimal prey size for the ruthless and efficient predators.
The ruthless and invasive stoat, bane to New Zealand’s birds.
All of these introduced mammals have greatly damaged the populations of New Zealand’s birds, who evolved in their absence for millions of years. The huia is no longer the first bird to sing at dawn, having disappeared in 1907.
The whio, or blue duck, is an endemic species to New Zealand threatened with extinction. Its current population is estimated to be around 3,000. The duck prefers to live in clean, fast-flowing mountain streams which have become degraded and lost as New Zealand’s human population has grown. Like many of New Zealand’s birds, they are also hunted by invasive mammals, such as stoats. This individual resides at the Auckland Zoo.
Restoring the Embattled Birds
Many of New Zealand’s birds are incredibly close to joining the huia, moa and Haast eagle in the finality of extinction. According to New Zealand’s Department of Conservation, there are only 142 kakapos left today, up from 51 in the mid 1990s. The large, awkward parrot has been hit particularly hard by the introduction of cats and stoats because it has very slow reproductive rates, only breeding every two to four years. When they do breed, 1/2 of the eggs are infertile due to low genetic diversity among the surviving kakapos.
All of the kakapos have been relocated to three predator-free islands off New Zealand’s coast, which has become commonplace for conservation in New Zealand. Small island’s offer easier confined spaces to eradicate pests, making them the final refuge for several species of embattled native birds.
Luckily, 2019 is looking like a record year for the kakapo as 52 live chicks were produced from 218 eggs laid since last December. This record-setting number of viable kakapo offspring is due to the help of cutting-edge conservation technology such as transmitters tracking which individuals have mated and 3D-printed eggs being swapped with actual eggs to allow the eggs to be hatched in captivity while not disturbing the mother’s incubation instincts. The recent sequencing of each remaining kakapo’s genome has even allowed a drone to inseminate willing kakapo females with semen from genetically-viable males, which is wild to picture.
Even the beloved kiwi has been knocked to the edge of extinction. New Zealand’s national icon had been decimated by stoats, cats and dogs for decades by 2016, when only 68,000 kiwis remained. Kiwi chicks already face long survival odds because they are abandoned when they hatch. Introduced predators effectively wipe out almost all of these fledglings. In addition to harvesting kiwi eggs in the wild and rearing them in captivity, an expensive and strenuous process, New Zealand has made a goal to become predator-free by 2050. This ambitious goal is key to restoring New Zealand as a bird haven.
But the only way to accomplish this is by conservationists getting their hands dirty, setting traps for stoats and cats where accessible and using cyanide-like poison called 1080 to target these predators in remote areas. Poisoning of feral cats in Australia has caused uproar from animal rights activists, but wide-scale poison is the only way to reduce the staggering numbers of these destructive predators. There is a choice between eliminating the pests or allowing native wildlife to disappear. In New Zealand, where 80% of bird species are at risk of extinction, this should not even be a discussion.
I was lucky enough to come across this kea in Fiordland National Park on the way to Milford Sound. The inquisitive bird was enamored with this red car, continually trying to pick rubber off of the windows and the tires.
The Plight of the Kea
It is important to understand what could be lost when thinking about conservation. New Zealand has so many amazing bird species sculpted by its remote location and predator-devoid ecosystems. One of these species is the world’s only alpine parrot, the kea, which has been completely eradicated from the North Island. Today, it soars through the icy pinnacles of the South Island’s mountains, its last refuge. In 2018, the incredibly smart parrot, which is called “Clown of the mountain” for its antics involving stealing tourist’s keys and picking rubber off of cars, was listed by the IUCN as endangered. The personable birds are at increased danger as their inquisitive nature leads to humans feeding them junk food and accidentally striking them with their cars. Most egregiously, a bounty was even placed on the bird’s head for attacking sheep until 1971, when 150,000 keas were killed, mostly by sheep farmers. Today there are only 6,000 left.
Only in New Zealand will you find a parrot flying through snowy mountains, capable of solving puzzles and willing to walk up and pose for humans. New Zealand’s incredible environments, from the high mountains where the kia lives to the forrest floor where kiwis and kakapos sift through the dark, and lack of predators offered an incredible space for birds to rapidly diversify into several strange and wonderful forms. But these very adaptations that helped them persist across New Zealand, from the keas curiosity to the kakapos bulk, have increased their chances of going extinct. Losing the moa was an incredible loss, and New Zealand needs to increase conservation efforts to save the kiwi and several other species from the same fate.
Check out more pictures of the kea and New Zealand birds at the Natural Curios Instagram page. Click on the icon at the bottom of the page!
All artwork and photography by Jack Tamisiea
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