Takahē: Back from the brink

Thursday, 15 November 2018

Rangers have figured out how to breed the birds in captivity. (First published November 2018)

It's been 70 years since takahē were rediscovered in a rugged corner of Fiordland. In the decades since, those dedicated to their conservation have become very good at breeding the birds, but this creates its own challenges. Michael Hayward reports.

At the bottom of a quiet Southland gully thick with red tussock, Glen Greaves hunkers down under a large piece of grey material.

Greaves, the Department of Conservation's senior takahē ranger, ignores the shrieking calls coming from a thick clump of native grass nearby.

A solid bird about half a metre tall dashes through a gap in the tussock, moving faster than its bulk would suggest. It's covered in feathers of a dark iridescent blue, with a green patch on its back, and a wide bill and stout legs of deep red.

Shortly after, takahē ranger Kerstin Schmidt walks over with a pair of large pale eggs, splotched purple-red, that she's raided from a nest. She places one into Greaves' cupped hand. It disappears into the darkness, where he shines a light into one end of the egg.

DOC takahē rangers Glen Greaves and Kerstin Schmidt with a pair of eggs found to be infertile.

* First population of takahē outside of Fiordland released into wild**

By shining a light through the eggs (known as candling), the rangers can check fertility by seeing if there is any development inside.

The process, known as candling, is how the eggs are checked for fertility. If there are no signs of life, it is taken from the breeding pair and destroyed.

This encourages the pair to try again before breeding season (early September to late December) ends. A breeding pair can make up to three attempts each season in captivity.

Greaves is checking the eggs from a pair named Miharo and Nuimea, who are usually good breeders. He is surprised to find the first egg infertile. The second is also.

This means Schmidt has the unpleasant job of destroying the nest and she scatters thick wads of dried tussock into the breeze.

The Burwood Takahē Centre has a mixture of breeding pens and runs for juveniles to learn the basic skills they will need to survive in the wild.

DOC rangers have learned that destroying a nest encourages another breeding attempt. If the nest is left intact, the pair may not breed again that season.

This happens at the Burwood Takahē Centre, the engine room of DOC's takahē recovery programme. It's effectively a farm, on the flat near Te Anau, but a farm like no other in New Zealand. Since it was created in 1985, it's become very good at breeding the rare bird in captivity.

In recent years, Burwood has boosted the overall takahē population by about 10 per cent annually, a rate of growth those overseeing the scheme think to be sustainable. The total population currently sits at about 375 birds.

But this prolific production has created a fresh problem: the new birds need a home, and there are not many places in New Zealand where it's safe to put them.

A trial of 30 takahē dropped into Gouland Downs in Kahurangi National Park in March is showing positive signs – all of the birds have survived so far and one group has laid eggs. Although there is space for up to 30 pairs there, it is too soon to know if it will prove a good home long-term.

Outside of that, its not known where they could go. The predator-free island sanctuaries are effectively full. The rugged and remote Murchison mountains above Lake Te Anau, where the takahē were rediscovered and a wild population still lives, will be at capacity by 2021.

And it's not a great home for them to begin with.

Dr Geoffrey Orbell (right) and Neil McCrostie with the rediscovered takahē in the Murchison Mountains on November 20, 1948.

DEFYING EXTINCTION

To be facing this problem at all is extraordinary, because the takahē was once so rare it was declared extinct.

The first recorded run-in Europeans had with the takahē was in Dusky Sound in 1849. A group of whalers followed the tracks of a large bird, which was chased and caught by their dogs. The whalers ate the takahē, finding it delicious, but kept the skin. It found its way to naturalist Dr Walter Mantell before being shipped to the British Museum in London.

In 1851, Mantell received a second skin from Māori on Secretary Island, at the seaward entrance to Doubtful Sound. It wasn't until 1879 that another one was caught, by a rabbiter's dog on the eastern shores of Te Anau.

A fourth was caught by a dog on the other side of the lake in 1898.

But sightings were so rare that the takahē was officially marked extinct the same year.

For five decades, there were nothing more than whispers of the bird's existence through unverified sightings. Then suddenly, the takahē became international news.

The bird was rediscovered by a group made up of Dr Geoffrey Orbell, Neil McCrostie, Rex Watson and his future wife, Joan Telfer. All four have since died.

Orbell's daughter Lynley Charteris was at Orbell's Te Anau lakehouse on November 20, 1948 – the day her father and his friends ventured into the Murchison mountains and made history.

She says her father, a doctor based in Invercargill, was 'a man who never stopped'. Over the years he took up hobbies ranging from collecting gemstones to building boats, making 96 over his lifetime.

Dr Geoffrey Orbell with a takahē in the Murchison mountains in 1998 – 50 years on from their rediscovery.

Orbell was 90 per cent sure he would find the birds before the group set off in his boat in 1948.

His confidence stemmed from an earlier visit to the area in April 1948, when Orbell heard some unusual bird calls and found tracks along the shores of a small lake. He measured the tracks by marking the stem of his pipe.

The group was more prepared in November, leaving Te Anau in the early hours of the morning with a video camera and a net.

After completing the steep walk to the lake, the group soon spotted two takahē. Orbell shot a roll of film before the group netted the birds and took photos.

Newly hatched takahē chicks are entirely black.

In the days following, he told The Press that the birds were making a 'penetrating, gulping noise' but were not scared of the group. 'They walked into the net of their own accord'. After an hour and a half the takahē were released.

The rediscovery was widely covered in the media, making it into papers and magazines as far away as England and America.

DECADES OF REFINEMENT

It's only in the last decade that DOC really mastered breeding takahē, though the success is based on years of refinements.

Although 50,000 hectares of the Murchison mountains were declared off limits to the public in 1949 – a rule still in place today – it wasn't until 1955 that a sanctuary was created at the Pukaha-Mount Bruce Wildlife Sanctuary in the Tararua District. Takahē were living there by 1957, but it took 20 years for the first chick to be successfully raised in captivity.

From 1984, takahē began to be transferred to secure island sites around the country, seen as an insurance policy if something catastrophic happened to the wild population in Fiordland.

A takahē chick being fed on Tiritiri Matangi.

A year later, Burwood was set up with six breeding pairs. Initially, eggs were artificially incubated and chicks reared using puppets and paper mache models – an approach that created birds that were poor parents, rearing half as many chicks as those born and raised in the wild.

Over the years, the programme had setbacks. An attempt to set up another population in the Stuart mountains, near the rediscovery site in Fiordland, proved unsuccessful because 58 birds were drip-fed into the area from 1987-92. They spread out without settling.

In 2007, a plague of stoats saw the wild population in the Murchison mountains plummet from 168 to 93 birds.

The fortunes of the species improved following 2011, when a new model was put into place at Burwood. It has more takahē onsite (they are now up to 24 breeding pairs), avoids artificial incubation where possible, and moves eggs between different nesting pairs to maximise production. It seems to be the recipe for successfully breeding takahē.

Greaves says its important to recognise the work done in the years before the changes were made, as it took that time to build a model that worked.

Though the species' genetic stock is robust, it's carefully managed, with birds frequently transferred between sites to prevent inbreeding. The programme moved 70 birds around the country last year.

All of this is working towards the overall goal of re-establishing takahē in Aotearoa. 'If we can't put them in places around New Zealand, we might as well give up,' DOC's takahē science advisor Dr Andrew Digby says.

DOC rangers work with wild takahē in the rugged Murchison mountains above Lake Te Anau in Fiordland.

The current recovery programme is split into four parts – the wild populations, Burwood, the offshore islands and other secure sites, plus advocacy and awareness work.

The whole thing runs on a shoestring budget – Greaves said the annual spend is about $590,000 including wages, with about $200,000 of that coming from Fulton Hogan. The programme also relies on organisations such as Air New Zealand, which provides flights.

A juvenile male takahē named Lowe at the Burwood Takahē Centre in Southland. There are about 375 individuals now and the population is growing about 10 per cent a year.

The breeding success means there is the breathing room to try things that would not have been possible earlier. When takahē were released into the Stuart mountains 30 years ago, the argument was over whether to put in four or five at once. When they were put into the Kahurangi National Park this year, it was whether to put in 30 or 40.

A DANGEROUS HOMELAND

The mountains which kept the takahē alive are not good habitat for the bird. The unforgiving hills provided a natural barrier from some predators which proved enough for the takahē to hang on, but the steep terrain and brutal weather is not ideal for a bird from a family better suited to living in flat wetlands.

The area remains free of ferrets or cats and has relatively low numbers of stoats, kept down by 3500 traps spread through 50,000 hectares of rugged terrain. They are checked several times a year, but don't catch much. During the last check, nine stoats and 13 rats had been caught throughout the entire network.

An orange triangle on a pole marks the site of the nest.

Science advisor Digby says studies have shown the wild population in the Murchison mountains would 'dwindle to extinction if we didn't prop it up'.

Its been known the population was in decline since 1971, but for decades it was not known why. In 2011, DOC staff started putting transmitters onto the takahē in the hills to understand why they were dying.

Digby says when the deaths are checked out, the cause is unknown for almost half, but the biggest proportion of those deaths with an identifiable cause is accidents, by 'quite some distance'. When staff investigate, they often find the birds have drowned or fallen off cliffs.

Three freshly laid takahē eggs have been found in a nest in Kahurangi National Park.

There's also limited room up there. Because the area is a low quality habitat from a food perspective (takahē mostly eat red tussock and other native grasses), breeding pairs have larger territories than they would at other sites, and they guard them fiercely.

Greaves says the Murchison mountains will effectively be full by 2021 if the programme keeps producing at its current rate. For the takahē to have a future, new homes will need to be found.

Though its early days, the Gouland Downs section of the Heaphy Track is looking positive as a new home for 30 takahē.

THE 1080 QUESTION

Big sections of the South Island would be good habitat for takahē – if the areas could be cleared of predators like ferrets and cats that would wreak havoc on a small population.

DOC takahē rangers Kerstin Shmidt and Glen Greaves head out to check egg fertility in one of the nesting pairs at the relatively flat Burwood.

Greaves says the birds are a 'generalist' species and should do well if they have enough grass, water and space.

He says wild sites need to be over 3000 hectares, so at least 30 pairs of birds could be moved in, enough to ensure their genetic security.

The terrain and climate at Burwood is fair more benign than that in the Murchison Mountains, but still gets a thick blanket of snow in the winter.

There are few such areas of tussock that are not home to predators (low numbers of stoats is OK but cats or ferrets are not), which is where 1080 comes into the equation.

Digby says the 1080 question keeps him up at night – how will takahē react to the controversial poison?

They are one of the few New Zealand birds (along with kākāpō) that are yet to be exposed to the toxin. It's never been used in their corner of the Murchison mountains.

Digby says the data shows trapping alone is not effective enough to set up predator-free areas large enough for takahē in places suitable for them to live.

With limited options in the conservation tool-kit, it means 1080 will have to be used until a better alternative is developed.

To further complicate things, the supplementary food pellets used at Burwood and other sanctuaries are based on a similar cereal to that used in 1080. Any takahē that have gone through Burwood (most of them these days) has had supplementary feedings a couple of times a week while there. They have been trained to eat the cereal.

Trials have found some (but not all) takahē will eat the type of cereal used in 1080, so work is underway to find a repellent that could be added which would put off the birds but still attract predators. It's thought the right smell will put the birds off, with substances such as tannic acid and d-pulegone (which has a peppermint smell) being trialled.

Digby says the results have been mixed so far – some individuals have been really put off but others are not.

He says it's unlikely there will be a silver bullet, but a number of measures could be put in place to minimise takahē interest in the poison.

Then there is the political element. Those on the takahē programme are keenly aware that any takahē deaths from 1080 will lead to negative backlash from anti-1080 campaigners. There would be huge pressure to stop using it, even if it prevents dozens more takahē deaths than it causes.

Solving the 1080 problem could be the last step to cracking the code of takahē conservation.

Greaves says if they can do that, they could 'spend the next 50 years filling up the Kahurangi'.