Migratory shorebirds are usually not a person’s first bird crush. They lack the supernatural aura of the resplendent quetzal, and they don’t go in for outlandish mating displays like that of the prairie chicken. As the Princeton University biology professor and shorebird-lover David Wilcove put it, migratory shorebirds can give an impression of being “little brown guys, buzzing around in the mud, not too big and not too small, and, whether one is a stint or a phalarope or a knot or a godwit, they’re just kind of there.” And yet, Wilcove told me, they are a birder’s kind of bird. Once people get to know them, they tend to fall in love. [...]
Migratory birds in captivity develop Zugunruhe, an agitated fitfulness, at certain times of year. Scientists don’t know precisely what provoked A34 to set off northward one spring afternoon, with a flock of her fellows, though, if they did, they might better know how her species will be affected by the shifting seasons of our changing climate. Godwits cannot soar like hawks or glide like albatrosses. They migrate by continuously flapping their wings. They must navigate crosswinds and headwinds, storms and maybe an occasional hurricane, continuing on day after day, night after night. As best as we can tell, they do not, while flying, eat or drink or sleep (at least not with more than one hemisphere of their brain at a time). After a journey of hundreds of hours and thousands of miles, they descend on a snow-covered shore at the Cook Inlet of southern Alaska or another favored breeding ground. They land considerably lighter than when they took off. “Many arriving shorebirds seem to be tired,” the ornithologist and conservationist Joseph Archibald Hagar wrote, in his foundational monograph, “Nesting of the Hudsonian Godwit at Churchill, Manitoba,” from 1966. In a field-diary entry, Hagar describes a group of birds that “within a minute or two dropped into some sunny spot out of the wind, tucked heads into scapulars, and went to sleep, not to move again for as long as we watched.”
In 1976, the young ornithologist Robert Gill took a job with the U.S. Fish and Wildlife Service in Anchorage. He was dispatched to the Alaska Peninsula to do biological inventories on public land that was up for lease to private companies. During those long-lit Alaskan summer days, walking across salt marshes and through the foothills of the mountains, Gill encountered thousands upon thousands of migratory shorebirds. He told me, “In Alaska, where the seasons are so prominent, it’s very dramatic. It feels like all the birds turn up over the course of one weekend in May.” Along with godwits, the peninsula was a summer home to yellowlegs, dowitchers, sandpipers, Arctic terns, and other species. But almost no one was aware that so many birds relied on this land. How the birds managed their journeys, where they might stop along the way, even how many of them there were—no one knew for sure. “In the vast expanses of wetlands and coastal tundra, you could see why,” Gill said.
The extinction of the once common passenger pigeon, famously described by the naturalist John Muir in his memoir (“I have seen flocks streaming south in the fall so large that they were flowing over from horizon to horizon in an almost continuous stream all day long, at the rate of forty or fifty miles an hour, like a mighty river in the sky”), was part of the impetus behind the Migratory Bird Treaty Act of 1918. Godwits are protected under the act, so killing them or holding them captive, even for scientific purposes, is highly regulated. Also, they’re difficult to capture. Gill’s means of learning more about them was limited, he said, to “the kind of observational work done by old-school naturalists.”
In October of 1987, Gill received a call about nine bar-tailed godwits that had crashed into a radar dome near Cold Bay, Alaska, and died. “They were greaseballs,” he recalled. “They made any Christmas goose look lean.” The carcasses were sent to a lab to be analyzed. Fifty-five per cent of their body mass turned out to be fat. Gill suspected that these chubby godwits were preparing to fly non-stop from Alaska to New Zealand, where this species wintered. However, at that time, the longest known non-stop migration flight was barely half that long. “But, if they were going to stop in French Polynesia, why carry all that baggage?” Gill reasoned.
The lab also measured the birds’ internal organs. Gill’s collaborator, Theunis Piersma, noticed something peculiar: the guts, gizzard, liver, and kidneys of these birds were very small—it was like cutting open a lion and encountering digestive organs the size of a house cat’s. Then, in March of 1992, some forty godwit carcasses were seized from a poacher in New Zealand. These were birds in a very different part of their migratory cycle, and their digestive organs, when analyzed, were of more normal proportions. In 1998, Piersma and Gill published their findings in a paper titled “Guts Don’t Fly: Small Digestive Organs in Obese Bar-Tailed Godwits,” concluding that the birds shrank their digestive organs to reduce their weight and their metabolic demands during a non-stop migration. And then, somehow, regrew them. [...]
A female godwit, E7, took off on March 17, 2007, from near the Piako River, on New Zealand’s North Island. She flew more than six thousand miles non-stop to a nature preserve on the Yalu River, near the China-North Korea border; she stayed there for a little more than a month; she arrived at her nesting area in Alaska on May 15th and spent the summer there. The tracker was still working on August 29th, when E7 started flying southeast, over the Pacific. Gill’s team was doing field work in western Alaska and had only spotty internet service; the team would gather around a laptop, waiting for the updates on E7’s location to come through. North of Kauai, she took a slight right turn and continued flying. On September 7th, after more than two hundred hours aloft, she landed at the mouth of the Piako River, back on the North Island of New Zealand, where Gill had first met her.
Before E7, the longest documented non-stop migratory-bird flight was that of a Far Eastern curlew who had flown about four thousand miles. E7 flew some seven thousand without a break. The flight defied reason. “I had an engineering professor at M.I.T. call me up and say he gave his students an assignment to compare the size and flight range of E7 to a 747 jet,” Gill said.
by Rivka Galchen, New Yorker | Read more:
Image: Ash Adams
[ed. Stan Senner was a friend and collegue. Didn't know Bob Gill personally but used his work frequently in my habitat protection efforts.]
