On September 28, one small bird completed a very long flight. An adult, male Bar-tailed Godwit, known by its tag number 4BBRW, touched down in New South Wales, Australia, after more than 8,100 miles in transit from Alaska 鈥攆lapping its wings for 239 hours without rest, and for the longest continual flight by any land bird by distance. And 4BBRW isn鈥檛 even done yet. In the next few days, the Godwit is expected to end its southbound migration in New Zealand after its well-earned island stopover, says , a builder from West Auckland and a passionate birdwatcher.
From his home office, usually reserved for managing building projects, Riegen keeps tabs on 4BBRW and 19 other Bar-tailed Godwits fitted with solar-powered location trackers. During migration season, he spends at least an hour each morning going through the most recent location data and writes a daily report for the ongoing project, run by the , an education and research nonprofit in Miranda, New Zealand, where many Godwits spend non-breeding months. All of the best tidbits he compiles are disseminated to the center鈥檚 followers on and , so that people can follow along with the birds鈥 cross-hemisphere, trans-oceanic journeys鈥攕peed bumps and all. 鈥淚t's such an amazing story,鈥 Riegen says. 鈥淲e want to share it as widely as we can.鈥
Although 4BBRW鈥檚 feat is astounding, it may not be particularly surprising. Bar-tailed Godwits are incredible migrants: Individuals have broken the 鈥渓ongest, non-stop, migration鈥 more than since satellite tracking began in 2007 and regularly make continuous flights of more than 7,000 miles.
In fact, 4BBRW previously held the world record for his 2020 flight of 7,580 miles. And just three days before 4BBRW鈥檚 2021 touch-down, a female godwit, tagged 4BYWW, completed a trip of a similar distance that was . While multiple subspecies of Bar-tailed Godwit make long distance journeys around the world, the New Zealand-Alaska population travels the farthest in its migration loop. 鈥淚t's this thing of imagination and magic that we have in this world, to think this tiny little bird traveled thousands of miles,鈥 says 爆料公社 Alaska executive director .
Unlike albatross or other long-flying seabirds, godwits are active flyers, not gliders鈥攖heir wings are moving the whole time. 鈥淚t just beggars belief, really,鈥 Riegen says. 鈥淚 mean, though I've known that for decades now, I still find it hard to imagine how anything can keep up that sort of effort 24-hours a day, without taking a break.鈥
Godwits begin their lives along coastal and estuarine breeding and nesting territory in Alaska, from the Yukon-Kuskokwim Delta to the North Slope. To feed, they use their long beaks to pull crustaceans, mollusks, and insects out of sticky mud. 鈥淢ove, feed, move feed鈥攁lways active,鈥 Dawson says. Juveniles can fly at just 30 days old, and by the end of their first summer, almost all congregate on the Yukon-Kuskokwim mudflats to fuel up. From there, only a few months after hatching, young Godwits join the previous generations and undertake a taxing first migration. Some birds will stopover in New Caledonia or Australia, as did 4BBRW, but many head straight to New Zealand.
The exact distance traveled varies from flock to flock and individual to individual. The birds make navigational decisions to optimize favorable winds and avoid severe weather鈥攁nd one tenth of a degree of difference in the starting angle could add or subtract mileage. Even with all these variables, godwits are startlingly accurate and consistent, returning to the same sites year after year and setting off on their migrations within a window of a few days. 鈥淭here's one particular bird that goes [north] almost exactly on the 25th of March every year and has done for 13 years,鈥 Riegen says.
When it's time to return to Alaska in March and April, the Bar-tailed Godwits follow a slightly different path, detouring to mudflats in parts of the Yellow Sea, before continuing. And this stopover habitat has been in recent decades, which was part of the reason the P奴korokoro Miranda tracking project began in 2019, in collaboration with in New Zealand and abroad. Globally, godwit populations have been declining amid growing threats of habitat loss and climate change. Researchers who follow this population want to know if the birds are adapting to habitat loss and finding other migratory routes. They鈥檙e also hoping to understand how young birds move around and select their non-breeding sites in New Zealand.
Only two years in, and the work has already yielded some surprising results. After the birds' initial journey from Alaska, ornithologists previously believed that juveniles spent their first few years in New Zealand looking for the sites they鈥檒l return to in the future and not moving around too much. Godwits don鈥檛 reach breeding maturity until about 3 years old, so there鈥檚 no reason for them to take the risk and waste energy flying back to Alaska before then. But tracking data has shown that young godwits do undertake big, additional flights early on. Young birds often join up with migrating adults鈥攎aking test flights up to 1,000 miles鈥攂efore they turn around, realizing they鈥檙e underprepared for the trip, says Riegen. And, in at least , a tagged, immature female bird completed the whole migratory cycle.
Adults, too, succeed in the face of incredible odds regularly. One bird this year, tagged 4BWRB, departed from Alaska and before hitting severe weather and turning back. Despite that false start, it tried again and reached New Caledonia just 17 days after its initial attempt.
鈥淵ou know, whatever we predict they rubbish us: just say, 鈥榶ou've got no idea what we can do,鈥欌 Riegen says. The birds鈥 ability to cope with extreme adversity makes the story of the Godwits an easy one to get people excited about, he adds. 鈥淚f your passion is nocturnal, endangered snails, you know, it's much harder to sell that to the rest of the world. But people can grab this story, and they can go and see godwits.鈥
Ultimately, he believes that the more people meet these birds, virtually or otherwise, the more likely they are to be protected鈥攚hich has made the hours writing Facebook posts worthwhile. He frequently encounters birdwatchers who come to P奴korokoro Miranda after having first learned about the godwits online. 鈥淭hey say, 鈥榳ell, I've been following this story and I had to come and see for myself.鈥欌