The trumpeter swan - a 25-pound adult female - was quiet as she was banded, tagged, checked for gender and painted with a bright yellow dye. She protested just once, flailing her legs as she was flipped onto her back so the underside of her tail could be dyed.

Trapped at Red Rock Lakes National Wildlife Refuge in Montana, tagged at eastern Idaho's Harriman State Park and shipped to the Fort Hall Indian Reservation, the swan was participating in an aggressive - and urgent - bid to move hundreds of scarce trumpeters out of the Yellowstone region.For all the uncertainties about the unique swan capture program, one thing has become clear: If the swans are left to winter in Harriman, they will run out of food and hundreds could die - some within about six weeks.

"The odds of them being alive at the end of the winter would not be very high," said Ruth Shea, an Idaho Department of Fish and Game regional biologist who has tracked the Yellowstone trumpeters for 14 years. "This is not the normal way you would do range expansion."

Instead, it's an emergency rescue. Faced with a shrinking swan food supply at Harriman, biologists involved in the hastily arranged transplant program are trying to move as many trumpeters as possible this winter.

Eventually, Shea would like to see the swans transplanted as far as the Midwest. But for this winter, biologists are settling for six warmer locations in Idaho, Utah and Wyoming.

Counting this transplant, 70 swans have been moved out of the Yellowstone region. But as the winter unfolds, more swans are apt to arrive at Harriman, and trappers will be even busier.

Last winter, more than 700 swans wintered at Harriman, or about one-third of the wintering population in the greater Yellowstone ecosystem. But this year, experts estimate there is only enough winter forage at Harriman for 100 swans. By mid-November, before the trapping got under way, more than 300 already had arrived, park manager Gene Eyraud said.

Trappers are unsure of the best way to catch swans in the winter since it has never before been done. So far, "spotlighting" has been the most effective method.

Using a loud portable generator and a light attached onto a football helmet, a biologist floats the Henry's Fork of the Snake River late at night and approaches a swan at close range. The light and noise stun the swan, which is collected in a salmon net.

But spotlighting does not work when the skies are clear and the moon is bright. Long before trappers can get in range, the swans see them and fly away.

"Basically, we're just trying techniques," said Rod Drewien of the U.S. Fish and Wildlife Service. "We don't know what will work and what will not work."

Other techniques may include swim-in traps and net guns.

Biologists also are unsure how the birds will react to new winter range, or if they will return to Harriman. One swan, released at Bruneau Dunes State Park in southwestern Idaho, returned to Harriman within four days.

"It may not be a total negative," Shea said. "That bird now knows a whole lot of habitat 250 miles south of here."

Biologists say it will be tough to break older swans of the habit of wintering at Harriman. They are more optimistic about cygnets and young adult swans.

So far, the captured swans are in good physical shape, even though conditions promise to get steadily worse. And that puts Harriman park officials in a delicate position. The wintering swans are a popular attraction with skiers and photographers, but the birds also are in danger.

"It's been a generally well-received program, but we knew we had to handle it right," Eyraud said. "We knew the public would fry us if we didn't do anything."