Migration experiment with a bird's-eye view

Research: A balloon will take geese south to see if they fly back on their own next spring. If so, the method will be used with rare swans and whooping cranes.

November 21, 2001|By Laura Vozzella | Laura Vozzella,SUN STAFF

WARRENTON, Va. - Ten caged Canada geese are dangling atop a flagpole here, getting ready to explore a question that sounds as silly as the strung-up waterfowl look: Can birds learn to migrate without flapping their wings?

Even a birdbrain knows they've got to flap to fly the hundreds and thousands of miles between their summer and winter homes.

That is, unless they hitch a ride on a huge helium balloon.

In an offbeat but earnest scientific experiment that could take flight as early as this weekend from a polo field in Castleton, in central Virginia, pilots will try to fly the balloon about 170 miles south with the 10 geese hanging off the gondola in cages.

It's a fanciful-looking rig, one you might expect to touch down over the rainbow. It could land instead in the annals of ornithology.

If the experiment works and the birds fly back north on their own in the spring, the researchers will try "passive migration" on rare trumpeter swans and whooping cranes. And they'll trade the balloon for a blimp.

"So little is known about how birds migrate. Do they use the stars? Do they look at landmarks?" said Harry Darlington IV, a balloon pilot and son of Antarctic explorers who organized the experiment with Dr. William Sladen, a wildlife researcher who founded Environmental Studies at Airlie in Warrenton.

"The objective is to know: Can a bird learn a migration route passively?" Darlington said. "Can it look at the ground and remember that route next spring?"

The two-year, $100,000 experiment is hardly the first unusual effort in the name of waterfowl migration. But the project has raised eyebrows even in a scientific field known for making birds think ultralight airplanes are their mothers.

Mention of the balloon project drew a chuckle from Joe Duff, who pioneered ultralight-led migration experiments with his partner William Lishman in 1994.

Their work inspired the movie Fly Away Home. Sladen's Airlie center trained geese for the movie and has placed trumpling swans on Columbia's lakes in an effort to reintroduce native swans to the region.

"I don't think it will work," said Duff, speaking by satellite phone from central Georgia last week, on a break from leading 11 sandhill cranes from central Wisconsin to a wildlife refuge near Tampa, Fla.

Duff said he has tried a passive migration experiment, shipping cranes in a closed trailer from Ontario to South Carolina, stopping every 50 miles to let them fly around and see landmarks, then boxing them up again. The birds failed to migrate back north.

"There's a good indication if they don't get there on their own steam, they won't [learn the migration route]," Duff said. "How do you convince a bird to look out the window? How do you make it focus on what you're flying over? We know from our studies that they don't use landmarks."

Bob Ferris, vice president for species conservation at Defenders of Wildlife, is more optimistic. His group considered a similar experiment three or four years ago but scrapped the plan, he said.

"People will think a lot of this stuff is kooky to begin with," Ferris said. "I think it has a good probability of working."

Like the ultralight projects, the balloon effort is aimed at restoring migratory populations of rare trumpeter swans and whooping cranes. That's considered important for the environment and for the birds because the migrating flocks might displace some non-native "resident" birds that deplete underwater grasses and cause other damage.

The project is starting with geese only because it is easier to get state and federal permits to work with those plentiful birds.

Passive migration by balloon or airship holds greater promise than the ultralight projects, which have had mixed results, scientists say.

"If our experiment is successful, we believe that the use of gas balloons or airships will much more accurately replicate a true migration, could significantly improve the safety and provide more flexibility with the weather and increase the number of birds that could be taught migration routes," Sladen said.

Balloons and blimps can travel farther than ultralights and can fly at night and in rougher weather, Sladen said, making the experience closer to natural migration, during which birds typically fly for eight to 12 hours without rest.

The passive method eliminates months of training because the birds are caged. For the 10 geese in the balloon experiment, training consists of being hoisted up the flagpole in crates made of plastic piping so that they can get used to being in the cages and hanging in the air.

Birds used in ultralight experiments need months of coaxing before they "imprint," that is, think of the plane or pilot as their mother and fly after it.

Eliminating that long training would save more than time and money. It would also protect the birds' safety because they can lose their fear of humans after months of contact with their handlers.

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