Birder’s Notebook: Bar-tailed godwit––Local research spotlights a superstar of long-distance migration
In October 2022, a four-monthold, Nome-grown bar-tailed godwit, “B6,” captured worldwide attention when it completed the longest nonstop migration ever documented in the animal kingdom.
Guided only by instinct, the young godwit covered an astonishing 8,330 miles over the Pacific Ocean from Alaska to Tasmania in 11 days of continuous, flapping flight.
Godwits are shorebirds. Unlike seabirds such as arctic terns, also famous for epic migrations, shorebirds are unable to land on water to rest or feed. Nor can they take a break and soar like raptors. Relying on constant wing action, wind, and the fuel they carry as fat, bar-tailed godwits span the globe twice a year between foodrich breeding grounds in the far north and bountiful wintering areas in the southern hemisphere.
In March, Alaska’s bar-tailed godwits leave wintering areas in eastern Australia and New Zealand on a 6,200-mile nonstop flight to the Yellow Sea between China and the Korean Peninsula. There, they spend four to five weeks gorging in rich, intertidal mud flats to replenish their fat reserves. Then, they launch again on another 4,200-mile nonstop flight to Alaska.
These spring odysseys are remarkable in themselves, and godwits are not the only shorebird species to complete them.
But that itinerary is surpassed by an even more astounding feat of endurance when the godwits fly south in the fall. Departing from the Kuskokwim River Delta, they flap more than 7,500 miles across the Pacific to Australia and New Zealand––the longest nonstop migration known.
Recently, a global audience tuned in to a Northwest Campus Strait Science Zoom presentation to hear wildlife biologist Dan Ruthrauff, from the USGS Alaska Science Center, tell the captivating story of his godwit research here. Against all odds, he and colleague Jesse Conklin, tracked the first migration of juvenile bar-tailed godwit B6, which surpassed all previously documented flights in both distance and duration.
Ruthrauff and Conklin tagged the now-famous young godwit as part of a research project on the Teller Road about 30 miles west of Nome in an area where bar-tailed godwits breed.
Shorebird research is important because many populations are in steep decline. It is estimated that there are 17 million fewer shorebirds today than in 1970. That is an overall decline of 37 percent, and 70 percent of shorebird species are believed to be declining. It is crucial to gain knowledge about all aspects of these birds’ lives, and where and when they face the greatest threats, in order to help reverse these trends.
Much is still unknown about the basic life history of bar-tailed godwits. Ruthrauff’s team set out to answer questions about chick growth and survival, juvenile survival, survival during migration and where the young birds settle and move on their wintering grounds.
To do that, they set seemingly modest goals: Find nests; track chicks before they fledge; determine growth and survival of the chicks; and follow their first migration with tiny satellite-tracking devices. But this work isn’t easy. As challenges mounted, it was clear why this information was still lacking.
During incubation, bar-tailed godwit parents are secretive and stealthy. Their cryptic coloration makes their nests, tucked into the tundra, exceedingly hard to find. Conklin had worked in the same area in previous years and managed to find nests. During their 2022 field season, however, he and Ruthrauff found only one. When they stumbled into broods of chicks already roaming over the tundra, they realized clutches had hatched earlier than expected.
Once the eggs hatch, the parents become loud and defensive, giving away the presence of nearby chicks, which the researchers hoped to capture and measure. Within five days of hatch, however, broods scatter widely. When parents sound an alarm call the chicks hunker motionless, vanishing into the tundra, hidden as effectively as their nests.
Eventually, Ruthrauff and Conklin located ten chicks from six broods. To keep track of the highly mobile young, they glued tiny VHF radio transmitters to the backs of the chicks, hoping to repeatedly relocate the chicks to determine growth rates and survival.
However, the chicks scattered widely, moving two to three miles a day over the tussocky tundra. Keeping up with them went from difficult to impossible once the chicks went out of radio range from the road. Ruthrauff and Conklin were able to track and measure the chicks’ growth for only one to five days.
The plan was to replace the VHF radios with small, solar-powered satellite tags, just prior to fledging, to track migration. This was seeming less and less possible when they encountered a brood of three chicks, about 22 days old––still too small to tag. But luck was on their side when they found the brood again four days later. Realizing it was likely their only chance, they put satellite tags on all three. It was a good call because it was the last time the researchers saw any chicks.
For the first two weeks after the chicks were tagged, the still-flightless youngsters moved around on the tundra of the breeding area. Then on August 3, from the comfort of their offices, Ruthrauff and Conklin were excited to see that fledgling B6 had flown to the Sinuk River drainage.
The transmitters of the other two tagged chicks never left the breeding ground. The harnesses were attached loosely to allow for continued growth and a doubling of body mass before migration. It is very possible that these chicks slipped their harnesses, leaving their transmitters on the tundra. Or the chicks may have died.
Adult bar-tailed godwits leave the breeding grounds before their young can fly. In mid-August, 90 percent of bar-tailed godwits breeding in Alaska gather in huge flocks on the lower Kuskokwim River delta to gorge before their epic migration, which typically begins in late August. Guided only by instinct, the juvenile godwits follow about a month later.
On August 6, novice flier B6 left the Seward Peninsula and flew across Norton Sound, coming to land near St. Michael and Stebbins. From there B6 continued south along the Yukon-Kuskokwim Delta, eventually settling north of Nelson Island on September 8.
B6 remained there until October 13, by which time most bar-tailed godwits are already wintering in Australia and New Zealand. The researchers feared that something might have gone wrong––that the transmitter had failed, or that the bird had died or wouldn’t migrate.
However, bar-tailed godwits have a knack for sensing low pressure systems and timing their departures to maximize help from the wind. On October 13, a massive low-pressure system moved in and B6 launched for the southern hemisphere, riding strong tailwinds through the Gulf of Alaska at speeds of up to 76 miles per hour.
Following an innate map and internal GPS, the four-month-old godwit averaged 32 miles per hour on its marathon 11-day, 8,330-mile journey over the Pacific.
Near the flight’s end, strong winds swept B6 past the usual godwit landfalls in New Zealand and eastern Australia. It seemed B6 might be blown to Antarctica, once again putting Ruthrauff and Conklin on the edge of their seats. It was an immense relief when the bird finally came to land on the northeast tip of Tasmania on October 24.
This longest documented migratory flight seems extraordinary to us mere humans, but perhaps it is nothing far out of the ordinary in the life of the amazing bar-tailed godwit.
For 13 days, B6 transmitted from the remote coastal, agricultural area where the bird landed. Then, the signal went off the air. Long-distance migrants lose significant weight during migration, which can cause harnesses to slip off the tagged birds. Or perhaps B6 died. No one knows.
But if B6 or its siblings, B3 and B4, are still alive, there is a chance their prominent leg flags may be spotted and reported. It is not known if bar-tailed godwits return to the breeding areas of their origin, but some similar species do. If so, we are in a prime position to see these birds. Keep a lookout!
Shorebirds
Shorebirds are a group of birds adapted for feeding in coastal areas and wetlands. They often have long legs for wading, and long bills for extracting invertebrates from mud, sand or wet ground. Many shorebirds breed in the far north, where the invertebrates they eat are plentiful in summer. Breeding shorebirds of the
Bering Strait region include godwits, curlews, sandpipers, plovers, phalaropes and turnstones.
These birds must head south before freeze-up cuts off their food supply. Long known for impressive migrations, the actual mind-boggling duration and extent of their travels was not fully realized until tiny satellite trackers enabled researchers to follow along virtually on their epic journeys. Many shorebirds such as bar-tailed godwits, whimbrels, bristle-thighed curlews and Pacific golden-plovers migrate to the southern hemisphere. The bar-tailed godwit’s southbound journey is the longest nonstop migration of them all.
EPIC JOURNEY OF B6 – The map shows the daily route and progress of four-month-old bartailed godwit B6 between the Kuskokwim River delta and Tasmania. The 8,330-mile nonstop flight took 11 days at an average speed of 32 miles per hour. With little prior flight time and no adult to guide them, young godwits follow an innate map and compass, propelled by wind and wings.