Tuesday, 21 Sep 2021

Back from the brink: The fish, lizard and bug being saved from extinction at Auckland Zoo

Think zoos, think baby pandas. But what about the baby bugs, lizards and more that represent the survival of some of New Zealand’s rarest species? Auckland Zoo has successfully bred 12 threatened natives – or 7187 individual animals. As Conservation Week draws to a close, Kim Knight talks to the experts.

A decade ago, Auckland Zoo – then home to elephants, lions and tigers – opened an enclosure starring species collected closer to home.

Director Kevin Buley says Te Wao Nui, the Aotearoa New Zealand track that spans six habitats from the coast to the high country, “represented a genuine paradigm shift in the role and purpose of the Zoo as a wildlife conservation organisation”.

But while more than six million people have since visited the $16.4m development, Buley says that’s just “the teeny visible tip” of a proverbial iceberg of locally-based conservation work that also includes vet hospital care for the likes of wild takahē, kākāpō and sea turtles, and fieldwork in conjunction with the Department of Conservation.

“Our breeding work in dedicated behind-the-scenes facilities for a wide variety of endemic New Zealand species in some instances now represents the last remaining place where they can be found on this planet . . . “

Black mudfish – around 350 of the rarely seen species have been bred at Auckland Zoo ahead of their first-ever large-scale release back to the wild.
Julie Underwood, lead senior keeper:

“They’re small, they’re brown and nocturnal. To see them you have to be out at night with a head torch spotlighting in a wetland – obviously not a lot of people do that. They’re a bit of a mystery fish and that boils down to where they’re found. There are not a lot of wetland areas.

“The adults are anywhere from 10cm-16cm long, roughly the width of your index finger. They’re not that colourful or exciting, but they’re unique to New Zealand and they have a lot of cool adaptations. The more you know, the more interesting they are. You don’t start out loving the mudfish . . .

“There are five species: Northland, Black, Canterbury, Chatham Island and the Brown. The black mudfish is found mainly in the Waikato, a little bit in Auckland, and up around Whangārei-ish, where they’re less common.

“They’re considered at risk or declining because over 90 per cent of our original wetlands have been destroyed. There are a couple of big protected wetlands in the Waikato and so we consider those strongholds for the species. We know they are surviving there and they are not going to go extinct, but definitely north of the Bombay Hills and all the little populations up to Whangārei – they’re not safe.

“Their name is really misleading. They like clear, still or slightly flowing water. The ‘mudfish’ part comes from the fact they have the ability to survive out of water. We call it ‘aestivation’, it’s similar to hibernation but it happens in summer. Some of the wetlands originally would dry up a lot over summer and the mudfish would burrow into the mud or under logs or leaf litter. As long as they stay damp they can absorb oxygen through their skin and they’ve got this thick mucous layer to help keep them moist.

“People would find them when they dug up mud – all these little wriggly fish that you never notice when the water is there. As soon as people started draining for agriculture and horticulture they started discovering them.

“If you protect the mudfish, you’re protecting the wetland and that benefits all those wading native birds and all the plants. Wetlands are really important in that they almost act like filters . . . the presence of mudfish is indicative of a healthy environment.

“Our founders came from the Hikurangi swamp, just north of Whangārei. They were brought in as juveniles in 2015. It took them a few years to get going, but to be honest, it’s a project that we just left ticking over. It’s in an abandoned aviary and it gets the reject equipment – we were basically wanting to leave the fish to it as much as possible in a natural setting.

“You can strip the eggs out and artificially fertilise them, but we wanted to learn about their breeding habits, to figure it out so it’s cheap and easy and low maintenance for other people to do as well.

“It was 2018 before we had our first spawning and now we get breeding every year. Some years we’ve had hundreds, some years it’s 20 or 30. When we make our breeding groups we don’t 100 per cent know how many males and females we have. There are ways to look at them under a microscope, but Covid really got in the way a bit over the past couple of years – our vets are just too busy.

“People hear the words ‘mudfish breeding facility’ and they’re like ‘oh, fancy’. And then we show it to them. It’s very DIY!

“It’s a far cry from what I imagine zoo keeping is in people’s minds. I wasn’t always an ectotherm keeper. I started out thinking I wanted to work with carnivores and I found working with native species really interesting – to be part of the breed-for-release programmes and the conservation work we do – it’s more technical and there are some really cool research and science aspects to it. If I can contribute to their survival in the wild that would be awesome.”

Cobble skink – known population of just 70 lizards, half of which were bred at Auckland Zoo.
Richard Gibson, Head of Animal Care and Conservation:

“New Zealand is famously a land of birds, but there are actually about 130 species of lizard, all of which are endemic, none of which occur anywhere else on the planet. They are an unknown, unsung and under-appreciated threatened species. They literally exist below the radar. I suspect most New Zealanders have never seen a New Zealand lizard.

“Conservation work that supports bird recovery can sometimes be detrimental to lizards. When you take some of the predators out of an ecosystem, other predators react. When there are few or no rats, mice numbers often explode. Mice are big predators of plants, seeds, insects, frogs and lizards.

“Native lizards are pretty cryptic. They’re secretive, they are low key and they are in horrible decline everywhere. Many, like the cobble skink, are as close to extinction as you can get.

“It’s relatively small, it has big eyes and it seems to be adapted to living in and around the large cobbles at the top of the beach, hence the name. We believe it’s a specialist to this little place on the West Coast of the South Island, called Granity. There’s a pub, and it’s literally behind that pub where the last of these skinks were known to survive.

“Cobbles are always shifting with high tides and storms, but because of the additional modifications humans have made – sea walls or turning great big flat areas into pasture – habitat pressures are much greater. And then we add in all the predators and suddenly we’ve got this perfect storm. And it was a storm that was their final problem.

“The Department of Conservation had been surveying and trying to understand how many cobble skinks were left. A cyclone was likely to wreck that habitat. They did an emergency salvage. They managed to find 34 and they sent them up to us, all packed up individually in little plastic ventilated boxes with screwed up paper towels so they didn’t shake around.

“In the meantime, Cyclone Gita hit. There’s not been a cobble skink seen there since. That leaves us with a safety net of a single population at Auckland Zoo.

Zoos specialise in intensive management. We’ve more than doubled the population now. They only have two babies at a time, matchsticks with legs, and they’re very, very fragile and very prone to any sort of dehydration or overheating. They don’t all survive.

“Some are maintained outdoors with a little bit of extra rainfall that we give them, some are managed indoors in a climate-controlled facility and we have another room, where we rear the babies. We’re spreading the risk but we’re also learning what works best.

“As lizards go, they’re very aggressive. The females beat up on the males and when those males get damaged they become stressed and immunosuppressed and susceptible to sickness. Now they only have occasional conjugal visits.

“We keep a studbook, or a pedigree. When we only have 36 “founders” every single animal’s genes are really important. We need to capture all that genetic material to give this population – this species – the best chance of long term survival, so their management can become less intensive and we can move groups down to a larger facility back on the West Coast . . . enclosures with natural beach cobble, seaweed and muehlenbeckia plants so they can sort of live naturally, but still under our protection and management.

“There’s a scientific computer program called Vortex that models extinction risk. If we run the cobble skink through it, we’re still really only looking at about a 50/50 probability this species is going to make it.

“Lizards are often pollinators of flowers and seed dispersers. They’re predators of lots of invertebrates and they’re a prey item for both natural and unnatural predators. Any animal has multiple roles in an ecosystem. The more holes you punch in an ecosystem, the more everything starts to go off track. In the long term, some plant, some flower, some insect, will be better or worse off. Some predator will have to change what it’s feeding on.

“Humans find it very hard to think along evolutionary and geological time frames. We live in our own little lifetime bubbles and we operate in the blink of a blink of a blink of an eye in time. These lizards have been here for 50 to 100 million years.”

Wētāpunga – since 2012, Auckland Zoo has bred and released 6049 wētāpunga into the wild.
Don McFarlane, curator of ectotherms:

“Biodiversity goes beyond pandas and blue whales and the animals that are so very charismatic. Their survival depends on the stuff you don’t really notice but has been around on the planet just as long.

“Wētāpunga were all over the North Island before they were knocked back to one natural population on Hauturu, Little Barrier island. They weigh around 45g, the heaviest on record was 70g, and they have been here 80 million years.

“There are lots of different wētā and a few species of the giant wētā. This one is the largest, and one of the rarest – the sumo wrestler of the giants. If you look in the Guinness Book of Records, under “bugs” there is a wētāpunga. It is world-beating.

“We’re all familiar with the tree wētā, particularly in Auckland. Superficially, wētāpunga looks the same but conducts its life very differently. It’s a little bit more cumbersome. It’s a little bit less aggressive and it will come down to lay its eggs on the ground making it very vulnerable. Its reproductive rate is different and it never adapted to being around introduced animals. They were really just about wiped out 200 years ago.

“Twenty years ago, DoC identified that wētāpunga needed to be put on to four other islands additional to Hauturu before it was considered safe. We’ve done eight islands now, in 21 separate releases. The more there are on islands, the safer they are.

“They are eaten by birds and to a certain extent we want that to happen. We’re basically just replacing a piece of the ecological jigsaw . . . one of the ways we can give them the upper hand is by releasing them when they’re much bigger.

“We’re in this lovely sweet spot, with the confidence in our breeding, where we can mix our strategies. We’ve done multiple releases on all these islands, overlaying wētā, not all from the same parents. We’re permitted to return to Little Barrier and collect a set number of founder animals and we’ve done that three times now, to overlay more genetic variability into the population.

“Baby wētā are super cute! They sit on your little fingernail and when they first hatch they’re a luminous green, you can almost see through their body and they’ve got antennae that are probably six or seven times the length of their body.

“It takes roughly a year from popping out of their rice-grain-sized egg through to becoming an adult, which is something like 200 times heavier. They go through a series of moults, and they literally take off their skeletons. They’re not like us, they have an external skeleton.

“Mammals invest a lot of time rearing their young to adulthood so they survive and pass on their genes whereas invertebrates go all out with these huge numbers in the hope that just a few will survive. We hugely sway the survivorship to their benefit. Up to 80 per cent survive and that just doesn’t happen in nature.

“One of the ways an invertebrate might lose its life is cannibalism – when they shed their skeleton they’re quite soft and if they time that poorly, another wētā might come along and nibble it.

“When we release the bigger ones, our volunteers chop up pieces of bamboo, which you can attach to trees with little sections of cotton at certain angles so rain doesn’t pour in. You remove a mesh bung, and the wētāpunga can come out when they want at night. And if someone forgets to remove the mesh, they can chew their way through.

“Humans are a funny bunch, we love rarity, we like to be proud of something that’s unique to us. I think people relate to wētāpunga because of its size. It takes up most of your hand, so it’s an ambassador for everything else. If you can start to get people on board for wētāpunga you can start talking about all the other invertebrates that are just as important.”

Auckland Zoo: Looking after the locals
– 10 years this month since the opening of Te Wao Nui, a $16.4m development, housing 55 native species across six habitats
– Nine species bred for release back into the wild: Pāteke (brown teal), whio (blue duck), kākāriki karaka (orange fronted parakeet), tara iti (fairy tern), brown kiwi, wētāpunga, tuatara, grand skinks, and Otago skinks
– Three species being bred for future release: Cobble skinks, Kapitia/Chesterfield skinks and black mudfish
– 41,400 field staff hours (worth $1.5m) donated to “wild work” in the past decade; around half in partnership with the Department of Conservation.

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