A Whooping Crane Migration Will Finish By Truck An effort to coax essentially orphaned whooping cranes all the way from Wisconsin to their wintering grounds in Florida has ended for the season. The problem this time isn't a possible violation of Federal Aviation Administration rules, but rather the birds themselves. "The birds haven't been cooperative,"" said Liz Conde, a spokeswoman for Operation Migration, the group that organizes the flights. "The birds are refusing to follow the ultralights any further."" The last time an Operation Migration pilot tried to guide them a few days ago, on a morning with perfect weather for flying, "the birds would just come out of the pen, fall in behind the ultralight, take off in beautiful formation, fly for a short bit and then break away."" "It's a game of "Can't catch me!" or something," she mused. The decision is something of a disappointment after an epic struggle to get the F.A.A. to allow the migration to resume. Acting on a complaint that the flights were commercial, and that the ultralights and their pilots are not certified for commercial use, the agency grounded the flights after the birds and pilots reached Alabama. It relented after a chorus of experts said that it was important to re-establish a wild population of endangered migrating birds, that this was the best way to do it, and that time was of the essence. It may already have been too late. The weather has been unusually balmy for this time of year, around 61 degrees today, Ms. Conde noted, and the increasing hours of daylight are a cue to the birds that winter is already waning. The birds may also have been undergoing some hormonal changes, she said. In any case, the only way to get the cranes moving will be to put them in crates and drive them by truck to the Wheeler National Wildlife Refuge near Decatur, Ala., she said, where six or seven whooping cranes, alumni of earlier migrations, are already wintering. Operation Migration has never led birds to Wheeler, only to Florida, she said; the wild cranes that are there now picked the spot on their own. But that's O.K., Ms. Conde said: "You never want to second-guess a wild bird." Wheeler is about 45 miles northeast, as the crow flies, from their current position. The cranes that are being trucked might return year after year to Wheeler or they might go elsewhere; no one is really sure. If they remain impressionable and fly with a group of other whooping cranes, they might make it to Florida next year, Ms. Conde said; or they might pair off with mates and fly to Florida. The group is posting progress reports on its blog.