Tracked bar-tailed godwits set new nonstop flight record for birds
In an avian flight of epic proportions, a female bar-tailed godwit lifted off from her Alaskan breeding ground and flew south 11,680 kilometers, nonstop, until she reached her winter home in New Zealand. Called E7 by the scientists who monitored her, she flew more than eight days without food, water or rest, on the longest direct flight by a bird ever documented, researchers report online October 21 in Proceedings of the Royal Society B.
“It’s phenomenal that a bird can go that far,” comments conservation biologist Geoffrey Geupel from PRBO Conservation Science in Bolinas, Calif., a conservation organization founded as Point Reyes Bird Observatory.
A research team also tracked eight other bar-tailed godwits, a type of shorebird, on what researchers call extreme endurance flights. Seven females, which typically have a wingspan of 30 to 40 centimeters, flew an average 10,153 kilometers over, at most, 9.4 days, uninterrupted. That’s the equivalent of flying from Los Angeles to London with 1,000 kilometers to spare.
The two males tracked flew slightly shorter distances over, at most, 6.6 days. But even these godwits shattered the longest nonstop flight record (as far as humans know), previously held by a Far-Eastern curlew that flew 6,500 kilometers over three to five days from Australia to China.
A team of researchers headed by Robert Gill Jr. of the U.S. Geological Survey Alaska Science Center in Anchorage implanted tiny satellite trackers in female godwits near the Alaska coast. Males, which are typically smaller, were harnessed with external (and lighter) satellite trackers on their legs. Scientists then monitored the changing coordinates of the godwits as the birds made their long flight over the Pacific Ocean.
Assessing the weather patterns in Alaska, the team also found that the godwits timed their departures to coincide with favorable tail winds that helped them fly south. “All birds took off with favorable winds,” says Gill, who added that tail winds caught in Alaska can shoot these birds 3,000 to 5,000 kilometers. “Some birds get shot almost to Hawaii,” says Gill.
Conservation biologists have documented well the impact of climate change on weather patterns that migratory birds depend on.
Weather changes have put some bird species out of sync with their food sources, have left birds trapped in a freezing climate or have caused them to miss narrow windows of time for correct migration.
This study details for this species the critical relationship between migrations and weather patterns. "Certainly we know that birds use weather fronts and wind, but no one has ever documented it like this," says Geupel.
Despite this detailed look at one species’ flight patterns, many questions remain. Scientists don’t know how the godwits assess weather patterns or navigate. What’s more, the satellite trackers can’t measure altitudes — the birds could be skimming the ocean or flying thousands of feet above the surface, says Gill. Future studies are needed to fully explain the species’ flight across the Pacific Ocean.
Gill Jr, R.E., et al. In press. Extreme endurance flights by landbirds crossing the Pacific Ocean: Ecological corridor rather than barrier? Proceedings of the Royal Society B.