On September 28, a small bird made a very long flight. An adult male bar-tailed godwit, known by its tag number 4BBRW, has landed in New South Wales, Australia, after more than 8,100 miles in transit from Alaska – flapping its wings for 239 hours without a rest , and setting the world record for the longest continuous flight of all landbirds in terms of distance. And 4BBRW isn’t even finished yet. In the coming days, the Barge is expected to end its southward migration to New Zealand after its well-deserved island stopover, said Adrian Riegen, a West Auckland builder and avid bird watcher.
From his home office, usually reserved for construction project management, Riegen keeps an eye on 4BBRW and 19 other bar-tailed barges equipped with solar-powered tracking trackers. During the migration season, he spends at least an hour each morning browsing through the most recent location data and writes a daily report for the current project, run by the PÅ«korokoro Miranda Shorebird Center, a non-profit organization of education and research in Miranda, New Zealand, where many barges go months without breeding. All the best pieces he compiles are distributed to the centre’s subscribers on Facebook and Twitter, so that people can follow the trans-hemispheric and trans-oceanic voyages of the birds – speed bumps and all. âIt’s such an amazing story,â says Riegen. âWe want to share it as widely as possible. ”
While 4BBRW’s achievement is astonishing, it may not be particularly surprising. Bar-tailed barges are incredible migrants: individuals have broken the record for “longest non-stop migration” more than once since satellite tracking began in 2007 and regularly perform continuous flights of over 7,000 miles.
In fact, 4BBRW previously held the world record for its 2020 flight of 7,580 miles. And just three days before 4BBRW landed in 2021, a female barge, tagged 4BYWW, made a trip of a similar distance that was briefly considered the record. While several Band-tailed Godwit subspecies make long journeys across the globe, the New Zealand and Alaska population is furthest from its migratory loop. âIt’s that imaginative and magical thing that we have in this world, to think that this tiny little bird has traveled thousands of miles,â said Natalie Dawson, executive director of Audubon Alaska.
Unlike the albatross or other long-flying seabirds, barges are active thieves, not gliders – their wings move all the time. âIt’s beyond belief, really,â says Riegen. âI mean, even though I’ve known this for decades now, I still find it hard to imagine how anything can sustain that kind of effort around the clock, without taking a break. ”
Barges begin their life along the coastal and estuarine breeding and nesting territories of Alaska, from the Yukon-Kuskokwim Delta to the North Slope. For food, they use their long beaks to pull crustaceans, molluscs, and insects out of the sticky mud. âMove, feed, move feed â always on,â Dawson says. Juveniles can fly at only 30 days, and by the end of their first summer, almost all congregate on the Yukon-Kuskokwim mudflats to refuel. From there, just a few months after hatching, the young Barges join the previous generations and undertake a difficult first migration. Some birds will stop over in New Caledonia or Australia, as 4BBRW did, but many will head directly to New Zealand.
The exact distance traveled varies from herd to herd and from individual to individual. Birds make sailing decisions to optimize favorable winds and avoid inclement weather, and a tenth of a degree difference in departure angle could add or subtract mileage. Even with all of these variables, the barges are surprisingly precise and consistent, returning to the same sites year after year and leaving for their migrations within a matter of days. “There is one bird in particular that goes [north] almost exactly on March 25 of each year for 13 years, âsays Riegen.
When it’s time to return to Alaska in March and April, the bar-tailed godwits follow a slightly different path, detouring over mudflats in parts of the Yellow Sea, before continuing. And this stopover habitat has quickly disappeared in recent decades, which is part of the reason why the PÅ«korokoro Miranda follow-up project started in 2019, working with other institutions in New Zealand and abroad. Globally, barge populations have declined amid increasing threats from habitat loss and climate change. Researchers following this population want to know if the birds adapt to the loss of habitat and find other migratory routes. They also hope to understand how young birds move and select their non-breeding sites in New Zealand.
Only two years, and the work has already yielded surprising results. After the birds’ initial voyage from Alaska, birders previously believed that juveniles spent their early years in New Zealand looking for sites they would return to in the future and not roaming too much. Barges don’t reach breeding maturity until around 3 years old, so there is no reason for them to take the risk and waste energy returning to Alaska before then. But tracking data has shown that the young barges undertake additional large flights early on. Young birds often join migrating adults – making test flights up to 1,000 miles – before turning around, realizing they are under-prepared for the trip, Riegen explains. And, in at least one case, a tagged immature female has completed the entire migratory cycle.
Adults too are consistently successful against incredible odds. One bird this year, marked 4BWRB, departed from Alaska and traveled 1,300 miles before encountering inclement weather and turning around. Despite this false start, he tried again and reached New Caledonia just 17 days after his first attempt.
âYou know, whatever we predict, they denigrate us: just say, ‘you have no idea what we can do,’â says Riegen. The birds’ ability to cope with extreme adversity makes the story of the Godwits easy to get excited about, he adds. âIf your passion is the night, the endangered snails, you know, it’s a lot harder to sell it to the rest of the world. But people can catch that story, and they can go and see barges. â
Ultimately, he believes the more people encounter these birds, virtually or otherwise, the more likely they are to be protected, which has made it worth spending hours writing Facebook posts. He frequently meets bird watchers who come to PÅ«korokoro Miranda after first hearing about barges online. They say, ‘Well, I followed this story and I had to come and see for myself. “”