Unlocking Migration's Secrets

Last August a female whimbrel took off from the treeless tundra of Southampton Island, which guards the iceberg-choked entrance to Hudson Bay in the Canadian subarctic, and set a course southeast.

Long-limbed and gray-brown, she was the size of a small duck, bearing the field marks that make this shorebird instantly identifiable—dark stripes on the crown of her head, and a long, thin, drooping crescent of a bill. It gives the whimbrel its genus name: Numenius, Greek for “new moon.”

Southampton had merely been a way station for her; some weeks earlier she had arrived there from her breeding grounds on the Mackenzie River delta in the Northwest Territories, some 1,500 miles and 52 hours of flying time to the northwest. Now her bill was stained purple from weeks of gorging on the autumn tundra’s bounty—blueberries, crowberries, and cloudberries, all of which her body had converted to thick layers of fat, fuel for the incredible journey ahead.

Tapered wings pumping without pause or rest, she flew east across Hudson Bay, passing thereafter over the rugged Ungava Peninsula of northern Quebec, then above the trackless boreal forests and wild rivers of Labrador. After 1,500 miles of unbroken flight, averaging 43 miles per hour, she left land behind, flying out into the open ocean somewhere south of Newfoundland.

Illustration by Peter Hoey

High Hope: A Whimbrel's Migration

It was here that she ran into trouble. Her flight path brought her into the remnants of Tropical Storm Gert, which was roiling its way up the north Atlantic. Fighting ferocious headwinds, the bird struggled to stay aloft as she plowed ahead at a painful crawl; for the next 27 hours her average ground speed slowed to a mere nine miles an hour.

Finally she broke through to the storm’s far side. Now, with the gale at last at her back, she rocketed along at 92 mph. In little more than 90 minutes she flew 150 miles to make landfall at Cape Cod—her first rest since she’d taken off from Southampton Island four days and 2,325 miles earlier.

That we know about this migratory drama at all, much less in such extraordinary detail, is thanks to a small satellite transmitter nestled among the feathers on the whimbrel’s back—part of a transformation in wildlife tracking that is making it possible for scientists to understand the movements of migratory animals with a level of precision unimaginable even a few years ago. They can comb through the chemical isotopes in a bird’s feather and learn where it spent the winter, sift the DNA in its genes to tease out how migratory populations are related to one another, attach minute devices that faithfully record its location for years at a stretch by just observing the time the sun rises and sets each day, or track threatened eagles in the Appalachians by tapping into the ubiquitous cell phone network (and thus help planners avoid conflicts with new wind farms). They have found that neighboring populations of the same species may take wildly different routes to far-flung wintering areas, and that many birds show an almost incomprehensible degree of fidelity to particular stopover and wintering sites.

With that new knowledge has come a recognition of what we’ve badly underestimated: the profound, almost universal role that migration plays in virtually every aspect of a wild bird’s life—and, with it, a new effort by dozens of researchers, agencies, and organizations like Audubon to better map these movements, better understand their significance, and harness this greater understanding for the benefit of birds.

“This new generation of telemetry has enormous potential for understanding bird biology and conservation,” says Steve Kress, Audubon’s vice president for bird conservation, and the founder of Project Puffin. “The new data loggers and transmitters could be far more important than bird bands, and future ornithologists may someday think of placing metal rings on bird legs as being as primitive as we might think of John James Audubon’s method of tying a silver thread to a phoebe leg. This is because these new devices give us the ability to track individual birds throughout the year—something that a band was never intended to do.” (To learn about the migratory secrets of some other individual species, from long-tailed ducks to pink-footed shearwaters and golden eagles, go to audubonmagazine.org.)

But by lifting the veil that has masked much of where and when birds travel, conservationists not only realize how little they know about migration. They’ve also learned, sometimes to their grief, that they have badly underestimated, too, the dangers facing these global wanderers—birds like the whimbrel named Hope.