environment

Tracking the mysterious kuriri

A GPS tracker successfully attached to the back of a small bird led to hugs and misty eyes at the Pukorokoro Miranda Shorebird Centre on Tuesday morning.

It was the culmination of months of effort by the centre staff, volunteers and a team of international scientists. It’s hoped the data scientists receive from the tag will help answer questions about why the numbers of kuriri, or Pacific golden plovers, visiting New Zealand are declining.

The shores of Miranda, in the Firth of Thames, are the part-time home to the kuriri. Thirty years ago they used to arrive in their thousands each year to escape the Northern Hemisphere’s winter. Now fewer than 200 visit.

Why the numbers coming to New Zealand have plunged is a mystery, as is much about the birds’ life.

Each year the small birds migrate to somewhere near the Arctic Ocean to nest. It’s not known whether this is Sibera or Alaska, what route the birds take to get there or if and where they might stop on the way. There’s speculation a habitat they might use as a stop-off point might be degraded.

Finding the answers could be the first step to stemming the birds’ decline.

“I had been asking where do they come from? I would get ‘We don’t know. Nobody knows.’ What do you mean nobody knows? It piqued my interests.”

Project volunteer leader JoJo Doyle said she had been asking questions about the birds for two or three years.

“I had been asking where do they come from? I would get ‘We don’t know. Nobody knows.’ What do you mean nobody knows? It piqued my interests.”

She and project coordinator Jim Eagles discussed how technology could be used to answer the questions. Like Doyle, Eagles had also been surprised at the lack of knowledge about the birds and had previously been in touch with an international plover expert, who suggested he would be happy to help if a project was created.

Funds for 10 $2000 light-weight GPS trackers were raised, permission was granted from the Department of Conservation and Massey University Animal Ethics Committee and a team of international plover experts were gathered from Montana State University and Brigham Young University-Hawaii for the week-long tagging attempt.

The volunteers have been watching the birds every day since November to try to make sure the attempt to catch some of the notoriously flighty birds was successful.

The volunteers mapped out the areas where the birds were gathered and noted how many there were, what they were doing, and whether tide levels or wind strength or direction changed their behaviour.

“We found out a lot about the birds we didn’t know before and we found out a lot of surprises. We would have these conclusions, but they would constantly prove us wrong.”

The birds shifted location several times over the months. It seemed they had finally settled in one area which would be ideal to set netting to catch them. An area had been prepared for the netting operation and plans had been made on how to “twinkle” the birds towards the net. Doyle describes twinkling as being a very slow, calm way to herd birds.

“A week ago they abandoned it completely.”

With one week before the international team experienced in attaching the GPS trackers' arrival, it was a mad scramble for the volunteers to document their behaviour patterns in the new area.

Monday’s attempt to catch them was unsuccessful. With information from the volunteers about the birds’ favourite flight area, the team went out at 3am Tuesday morning and caught two birds. One male and one female, both adult and large enough to carry the few extra grams of the GPS tracker on their migration.

It’s hoped another eight will be caught and be fitted with the GPS trackers.

“We’ve fallen in love with these birds. We’re enamoured with their personalities.”

Montana State University ecologist Wally Johnson is a plover expert and has put trackers on birds in Hawaii where some Pacific golden plovers winter. The discovery was the birds fly directly to Alaska to nest, a journey of 4800 kilometres which takes the birds about three days.

He’s also fitted trackers to birds south of Hawaii.

“For birds south of Hawaii, it’s probably too far for one big flight. They go to Japan, spend about 20 to 30 days there fattening up and then make the last part of their flight to Siberia.”

He said he doesn’t know if New Zealand’s kuriri will stop in Japan, but thinks there is a good chance it will.

While in Japan, he said the birds stay in rice fields where they can eat insects and worms.

He said in Alaska there is also plenty of good habitat for the birds.

Climate change could affect vegetation which is important for ground-nesting birds.

“In the long-run, that’s really the big threat, as well as sea level rise, which will eliminate some wintering grounds.”

He hopes the trackers will provide “fundamental knowledge”.

“Without that information you can’t make sound decisions in respect to conservation efforts.”

The GPS tracker is attached to the kuriri's back with glue and a nylon harness. Photo: Farah Hancock

The trackers will send information to satellites at intervals set by scientists. Catalina Amaya-Perilla, a representative from the tracker manufacturing company Lotek, is on hand at the shorebird centre for the tagging week to ensure the GPS trackers attached to the birds were functioning correctly.

Deciding how often the trackers are triggered to send information to satellites is a balancing act.

“The more GPS fixes you take the less battery life you’re going to have,” said Amaya-Perilla.

Solar versions of the units are too heavy for the small kuriri.

It’s hoped the batteries will last an entire year so the kuriri’s return journey is also tracked in case the route is different.

The progress of the kuriri will be updated on the Pukorokoro Miranda Shorebird Centre’s website so the public can track the migration along with scientists.

The birds are expected to migrate in the first few weeks of April.

Doyle, the volunteer team lead will continue to help with trapping efforts for the rest of this week and then monitor the birds to ensure the GPS trackers remain attached until migration. Once they’re gone she said she’s going to feel a little lost not visiting their favourite spot.

“It’s like their playground. They feed there, they bathe, they chase each other. They love it. I’ve videoed it on my iPad. We’ve watched it with our binoculars. We’ve laid on our tummies in the evening at twilight and watched this magical time they have.

“We’ve fallen in love with these birds. We’re enamoured with their personalities.”

Doyle said she’ll be visiting the website often to track the birds’ migration after they leave New Zealand in April, one bird's progress in particular is likely to be of interest. The female kuriri caught on Tuesday was nicknamed JoJo after her.

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