Saving New Zealand's rarest bird, fairy tern/tara iti, with help of a pink thermos

Saturday, 28 November 2020

Watch Department of Conservation staff return critically endangered fairy tern eggs to their nest after a storm in Mangawhai during the 2020 breeding season.

When bad weather threatened four vulnerable fairy tern eggs at a Northland beach, Department of Conservation rangers swung into action, saving the rare eggs with an unlikely household item. Josephine Franks reports.

A lot of high tech kit goes into protecting New Zealand’s rarest bird.

The number of adult tara iti, or fairy terns, hovers below 40.

To try to boost the numbers, eggs are whisked from their nests when bad weather threatens. At Auckland Zoo, incubators mimic the conditions under the mother as closely as possible, automatically turning the eggs every hour, maintaining Goldilocks-like levels of humidity and temperature.

But it’s a pale pink Kmart thermos flask that’s the hero of the operation.

Ayla Wiles sets off on the last leg of the journey returning fairy tern eggs to their parents’ nest.

There are fewer than 40 adult fairy terns in New Zealand.

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The route to the fairy terns’ nesting spot winds through unmarked sand dunes.

In the gravel car park of a private estate near Mangawhai, Department of Conservation ranger Ayla Wiles dunks a thermometer into the flask full of water. Behind her, a triangle of blue water beckons where the car park gives way to the beach.

Wiles has just spent a 90-minute car ride with a travel incubator snug between her knees, three thermoses of warm water in the back. She’s the temporary guardian of four tara iti eggs on their way back to their parents’ nests.

Thirty-seven degrees is the temperature she’s looking for; a splash of cold water brings it right. She dumps the water on the ground, stuffs balls of cotton wool in its place, creating a warm cushion for the eggs on the final leg of their journey. The eggs go in, then more cotton wool on top.

The tara iti eggs nestled into the incubator at Auckland Zoo, where they are closely monitored.

And then we walk.

You can get to the beach where the fairy terns nest by boat, or if you go the long way, by quad bike. But the easiest route is a march over the savannah-like dunes.

Once a day, the eggs are 'candled” – held up to torchlight to see what’s happening inside.

We cut along the shoreline, high tide pressing us into the trees as we play chicken with the creeping waves. The two DOC rangers stride ahead, cradling their thermoses. They follow an invisible path through the unmarked dunes until we emerge onto the beach, Whangārei heads laid out before us.

Fairy tern ranger Jacob Ball braves the swirling fairy terns to swap out their eggs.

The changeover is a swift operation, with dummy eggs swapped for the real thing.

Angry birds overhead is a good sign – it means they've accepted the dummy eggs as their own.

Tape dissecting the dunes and a small white wooden shed – the hide – just beyond the fence line are the only signs we’ve reached the nesting place. That, and the two other DOC rangers waiting for us.

Fairy terns need a lot of hand holding to ensure their survival. It’s a full time job – literally. Shannan Courtenay and Jacob Ball, DOC’s Mangawhai fairy tern rangers, are stationed at the beach 40 hours a week.

For the five-month breeding season, a team of rangers and trained volunteers work across the four tara iti nesting sites at Papakanui Spit, Pakiri Beach, Waipū and Mangawhai sandspit. The intensive monitoring showed good results last season, with seven chicks fledged, boosting the population by 20 per cent.

The four eggs that are about to be returned to the nest were removed two weeks prior when a big storm was coming in. Tara iti scrape their nests into banks of sand and shells, leaving them vulnerable to stormy weather and high tides.

Auckland Zoo is always on standby to receive eggs, but the 10 they’ve been looking after is more than they are used to, the zoo’s senior lead bird keeper says.

Catherine Francescon or one of her team visits the eggs at least three times a day to manually turn the eggs – on top of the automatic rotation they get in the incubator. “We’re quite obsessed with making sure the eggs are turned.”

All that movement helps mix up the nutrients and protein within the egg, which the embryo feeds on while it’s developing.

To get a better look at the eggs, once a day the zoo staff examine them with the lights turned off. Hold a fairy tern egg up to a torch and you’ll see a spider web of blood vessels in silhouette. From day three signs of life are visible; staff look at the same time every day to make sure they are growing as they should.

Back up at the cordon, Wiles and Ball are ready with their thermoses.

There isn’t a collective noun for fairy terns: there aren’t enough of them. But as the rangers get ready to approach the nests, at least seven birds swirl into the air – a fifth of the New Zealand population. This is what Wiles was hoping to see. They’re protective of their nests, which means they’ve accepted the dummy eggs left in their nests as the real deal.

The rangers crouch behind the hide, clutching a thermos each and waiting for the right moment to scurry in. The changeover is swift. One dummy egg goes and out and two real ones go in. The birds settle back in. It’s a success.

So if the egg swap worked, does that mean we’ll see the population bolstered next year?

It’s early days, Wiles cautioned.

Three of the four eggs hatched in the days following the transfer, but there’s still the summer to get through, and any bad weather could easily upset things.

The lesson here: don’t count your chicks before they’ve fledged.