This rare takahe, Hawkeye, arrives on Hauraki Gulf's Rotoroa Island today. Photo / Department of Conservation
His name is Hawkeye – and for one of New Zealand's rarest species, he's a symbol of hope.
The hefty adult takahē today arrives at his new home – Hauraki Gulf's Rotoroa, or "Love Island" as conservationists jokingly call the offshore creche – with high hopes that he'll hook up with a female named Silberhorn.
Such is the tiny population of takahē – there are still only about 400 birds, despite numbers annually growing 10 per cent – that birds like Hawkeye can make all the difference to the recovery of the flightless icon.
BACK FROM THE BRINK
Because of their similar appearance, they're often compared with the much more common pukeko – but, while they share a common ancestor, they're only distantly related to the scrappy swamp denizens.
They're also much larger, and much more colourful, sporting peacock-blue shoulders and turquoise and olive-green wings that are only used for display during courtship – or to signal aggression.
A survivor of an era when New Zealand was home to an abundance of large, flightless birds, the species has somehow managed to cling on in the face of hunting, habitat loss and wave after wave of introduced predators.
By the time of European settlement, takahē were already reduced in numbers and localised in distribution.
Only four takahē were sighted in the late 19th century, and by the early 20th century, they were considered extinct.
That assumption changed in 1948, when Invercargill doctor Geoffrey Orbell rediscovered the bird high in the tussock grasslands of Fiordland's Murchison Mountains.
At first following their rediscovery, experts believed takahē were safest left alone in their mountain haven.
The rugged Murchison Mountains of Fiordland were declared a "special area", off limits to all except a few scientists and deer cullers.
By the early 1980s, research revealed a serious drop in numbers, kicking off a major conservation push to save them.
Over the years since then, a huge effort has gone into studying takahē and the threats to their survival.
Actions to save them from extinction have included deer control, manipulating wild nests and eggs, artificially incubating eggs, captive breeding and predator control.
"The long-term goal is to have self-sustaining populations in the wild - ideally within their historic range," said Phil Marsh, the programme's secure sites ranger.
"Everything we are doing with takahē management, including small island populations, are designed to get us to that goal as quickly and safely as possible."
At the Department of Conservation's Burwood Takahē Centre in Te Anau, the national recovery programme's largest and most productive site, there were now up to 100 birds, including 25 breeding pairs, at any one time.
Eggs are left on the nest rather than placed in artificial incubators and chicks are left to be reared by adult takahē, instead of models and puppets.
Elsewhere, takahē were scattered across a range of other sites – among them, Cape Sanctuary in Hawke's Bay, Waikato's Sanctuary Mountain Maungatautari, and Kahurangi National Park, where birds were recently released for the first time in a century.
Instead of being handled in sub-species, like kiwi, takahē were managed as one large population.
EASING THE BOTTLENECK
As with other severely diminished species like kakapo, takahē suffered from a bottleneck of genetic diversity.
With little of it, the birds were more susceptible to disease, or coming threats like climate change.
Marsh singled out the late Dr Ian Jamieson for his expertise in developing genetic management as a critical species recovery tool, which DoC has been rolling into its work since the early 2000s.
Once evidence of inbreeding became concerningly clear among takahē, real effort to turn the tide on the country's small offshore island populations began in 2010.
"We aim to ensure that the diversity that is left is as secure as possible through intensive management and spreading the risk," Marsh said.
To pick the best pairings, the recovery team tried to estimate the relatedness and relative rarity, and then gave each potential couple an "RX" value.
There have now been 47 recorded "founder lines" in the takahē population, of which there were 42 still available to use.
"Every bird taken from the Murchison Mountains from unknown parentage has been considered a founder, and therefore potentially holding rare [genetic variants], despite the likelihood that some of these will be closely related to each other," Marsh said.
Still, Marsh said the entire gene pool couldn't be widened, as it were.
All the team could do was ensure that the diversity they currently had wasn't lost through genetic drift, which occurred when species stopped exchanging genes.
"This is done through trying to amplify the rare bird lines through nest management, and ensuring pairings are as appropriate as they can be."
It was also tough to directly measure genetic benefits, as the team didn't currently have the tools to look at individual gene level.
"We can only look at indirect results, such as survivorship and productivity."
The Burwood population was designed to comprise the most under-represented genetic lines, as this offered the best opportunity for amplifying them across the wider population.
Yet, there was still the risk the site could be wiped out – and the other sanctuary sites were there as insurance.
"As such, it is critical that founder lines are spread well through these populations, with the rarest individuals prioritised for the safest sites."
Ultimately, he said takahē were set apart in that the majority of available genetic diversity was represented in a population that could be intensively managed.
"Also, the breeding biology allowing for forced pairing, and up to three nests per year can be induced, meaning we can target rare lines and rapidly grow them."
'LOVE ISLAND'
Rotoroa, an idyllic 82ha patch of land reachable with a one-hour ferry trip from downtown Auckland, was once better known as a refuge for recovering drug and alcohol addicts.
Managed by the Rotoroa Island Trust, it's become home to some of New Zealand's rarest wildlife: takahē thrive there alongside kiwi, pateke (brown teal) tieke (saddleback) and moko skinks.
"The island is like a creche for the takahē - we nurture the chicks in a safe predator-free environment," trust ecologist Jo Ritchie said.
"Rotoroa Island also acts like a bit of a 'Love Island' for the takahē. Birds come in and we hope they will get on, form pair bond relationships and mate.
"But we also need to send them packing when they reach a certain age to find a mate in the South Island. They are a special part of the Rotoroa Island family - we know them all intimately."
Teina, a chick, and Aupiki, a yearling, would be transferring back to Fiordland this week – becoming the second and third chicks successfully bred on the island and then sent south.
Ritchie described Silberhorn, who arrived on the island in 2015, as something of a matriarch of the Rotoroa family.
She had successfully reared a chick every year for three years.
"Silberhorn rules supreme and has been coaching her offspring on how to rule the roost, taking them on tour to visit her minions in the far flung regions to the north and south of the island, occasionally chasing away the other pairs and raiding their pellet hoppers," Ritchie said.
All eyes would be on her and Hawkeye, who, with Silberhorn, would make up Rotoroa's third breeding pair.
"We welcome Hawkeye to the island - and hope he finds love."
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