Thousands of bar tailed godwits have arrived back at feeding spots across New Zealand after an 11,000km migration from Alaska for spring and summer.
It's the longest non-stop flight undertaken by any bird.
This year researchers have been able to keep track of every move of some making the journey, as part of a project to learn more about their decline on our shores.
Godwit researcher Tony Habracken's been on the welcoming committee at Pukorokoro Miranda, on the Firth of Thames, one of our premier spots for godwits.
He's been following godwit birds since he was about 11 and at this time of the year he's on the shell banks for hours on end.
"Probably more than my wife would like me to be out," he told 1 NEWS.
"There're about 3000 godwits here at least and we could probably see an increase in numbers in the coming months," Habracken said.
Last year, 20 Godwits feeding at the Firth of Thames were fitted with solar-powered transmitter backpacks.
That's made the work done by Habracken and others in the shorebird research community simpler this year.
"With this new programme we've got going I've got the ability to be down here when we think the birds are going to arrive and meet them on the day," he said.
In 2007, satellite tagging successfully recorded the travels of a bird dubbed E7 from New Zealand to East Asia and Alaska.
The tracking then proved her journey back to our shores was direct.
"We've known that all of our godwits must be doing this flight but we haven't really been in a position to put satellite tags on that give us that real-time information until this year," Massey University’s Associate Professor in Zoology Phil Battley said.
He said the tracking technology has come a long way since 2007 and this time researchers have been able to get a better picture of the birds’ routes and the weather conditions they’ve encountered.
"There are adults that have migrated, that haven’t got to New Zealand yet," Habracken said.
"We'd expect them to arrive back but on their journey south of Alaska the easterly winds that came through the subtropics, drew them into more westerly areas, and they've landed in New Caledonia and in Australia.
"In the past it's just been random, chance sightings and this year now we've been able to track them okay.
"We know these birds are somewhere else in the skyway and have stopped off... we've always been aware birds have stopped off in odd place, this gives us context".
Battley said this year it was "quite a difficult migration for them".
"The winds have been often adverse, from large storms in the North Pacific and headwinds, through to persistent easterlies across the entire route.
"What's unique is the fact that so much of their flights are over vast stretches of ocean that don't really have emergency stop offs, so we're really getting insights into the possible role that little islands may have on the evolution of this whole migrating system.
"We know of some birds in Fiji in previous years," he said.
But researchers expect the birds that have either found somewhere to take a break or been blown off course to return to New Zealand.
Battley said a bird currently in Rockhampton is "probably having a fabulous time in a lovely tidal flat with godwits that probably wanted to go there, and I'm anticipating within the next month we may see it come back down and return to NZ".
Anyone's able to check in on their progress here.
"The need for this research is just growing and growing because of the pressure on their habitats, and we're seeing changes in migration habits, we are seeing changes in migration timing," Battley said.
"Birds are migrating earlier than they used to in New Zealand, and it’s possible that a reason for that is degradation of their habitat and major loss of food resources.
"Loss of tidal flats may mean that it takes birds longer to refuel. So, this work is tying in with other monitoring that we are doing in NZ and around the flyaway trying to figure out what’s happening with these birds.
"We know their populations are going down and we're trying to pinpoint what the cause of that is".
Battley said Covid-19 impacted the project with colleagues in the Yellow Sea region unable to conduct on-ground evaluations of the habitat due to Covid-19 restrictions, but says the project is still providing valuable insights into the species.
He says the other important factor for godwits is the weather.
They rely large scale weather systems for favourable winds at the start of their migration.
"So godwits leaving Alaska are very selective and ideally when a large storm system comes across and passes by Alaska, they get really good tail winds for the first 1000 - 2000km of their journey," Battley said.
He said climate change may alter the frequency and timing of these storm events, and it's unclear if this will make it better or worse for the godwits.
Habracken's completing separate research, about how long it takes birds to recover from the mammoth journey.
"It's just discovery, anything that's new is always great," he said.
Some of the most recent to complete the 11,000 kilometre migration from Alaska are the juveniles, who are at best just 14 weeks old.
They'll now stay in New Zealand for a few years and work out which part of the country they like before they're ready to breed and make the pilgrimage part of their annual routine.
For the next six months though godwits of all ages will be visible on New Zealand shores.
"From Parengarenga Harbour in the north to Invercargill, all the suitable harbours would have godwits," Habracken said.
The godwits will be resting, moulting their feathers and fattening up, ready for their next big journey in March.