Bird Files: Tundra Swans Fly High with Precision

March 27, 2015

Like many birds, Tundra Swans are on the move these days. And right now, mid-to-late March, is a good time to see them flying over Pennsylvania. They’re traveling from their winter homes on the mid-Atlantic coast and the Susquehanna River Valley—and heading to their summer breeding grounds in the high Arctic.

Tundra Swans are long-lived, large white birds with a wingspan of nearly six feet. They are distinguished from the curved-necked Mute Swans by their straighter posture and mostly black bills. Touches of yellow on the bill, right near the eyes can help to distinguish them, too.

They fly in a "V" formation like geese.  It is an ingenious method, one that is important for birds traveling a long distance because it helps them save energy.

Scientists long theorized that birds use the disturbed air coming off the one in front, based on what they knew of aerodynamics. It’s only in the last decade, that they have been able to measure the phenomenon.

Tiny data monitors attached to Northern Bald Ibises—that also fly in "V" formations—confirmed two things.

First, as suspected, the birds position themselves in the right place—just off to the right or left of the bird in front of them--to take advantage of the “upwash” of air coming off the wings of the front bird.  Second, they also make sure that their own flap is timed perfectly to use that air current to its best advantage.

What really surprised researchers is that the birds’ use of this “good air,” is very consistent. They had only expected birds to stay in the sweet spot 20 percent of the time—but found them doing it nearly 100 percent of the time!

Watch for this synchronicity next time you see a "V" formation of birds. If you want to identify them as Tundra Swans, though, you may have to use your ears. Flocks are noisy. It’s said they can be heard up to three miles away. Listen for loud boisterous calling that may sound like Canada Geese at first or even barking dogs. Once they come closer, you’ll be able to discern their softer and more melodious tones. If they are close enough to the ground you may hear the mechanical whistling noise of their wings.

By April, Tundra Swans will have reached their Arctic breeding grounds on the tundra for which they are named. If you miss them this spring, try again in fall—and be sure to listen for them.

Bird calls for this segment come courtesy of The Macaulay Library at the Cornell Lab of Ornithology, and were recorded by Wilbur L. Hershberger.

Photo right: Tundra Swans fly in "V" formation. Credit: U.S. Fish and Wildlife Service