New research blames some feathery Canadian residents for the dramatic crash-landing of a jet into the Hudson River.
Researchers from the Smithsonian Institution say the birds that hit the engines on US Airways Flight 1549 just after it took off on Jan. 15 were Canada geese migrating south from Labrador.
Authorities initially thought the avian culprits were native to New York, but a research team at the Smithsonian found evidence that they were from Canada.
Carla Dove, director of the feather identification lab at the Smithsonian, and her group analyzed 69 bags of "snarge" - the institute's name for what remains of a bird after it has collided with an airplane - from the Airbus A320's engines retrieved from the bottom of the river. A DNA test identified the birds as Canada geese. Additional tests compared isotopes in the feathers to Canada geese from across North America.
"The samples were nowhere near resident birds," Dr. Dove said yesterday in a telephone interview from Washington. "They were closer to birds in Canada."
The isotopes suggest the geese bred and molted in Labrador, said Peter Marra, a research scientist with the Smithsonian Migratory Bird Center.
Dr. Marra said their research has even managed to identify the sex of the birds: At least one female hit one engine and a female and a male hit the other.
"Now we're doing some geotyping to see if we can identify individuals and try to determine how many birds hit the engines," he said.
Why were the birds flying past at the time? Dr. Marra said it may have had something to do with a recent snowfall that had blanketed New York green spaces.
"Canada geese are essentially flying cows," he said. "They're grazers. They graze on grass and they look for open fields where they can get food. If those open fields are all of a sudden blanketed with snow, if a lot of the open water is now frozen, they're forced to move -- and I think that's what was happening here."
Airlines and transport authorities control native bird populations by killing them or scaring them away from airports, but can do little to prevent collisions with migratory birds. "It gets much more complicated. You can't just guess when they're going to be there," Dr. Marra said.
Aircraft engineers have researched ways to make planes more visible to birds, but Dr. Marra questioned the effectiveness of altering the exterior of a plane.
"You've got this big, loud plane coming at you. I don't know how you could be any more visible to the birds." Dr. Marra and Dr. Dove said the best way to prevent migratory bird strikes is by using bird-detecting radar.
"If you've got birds used to moving around, you're going to need more sophisticated tools," Dr. Dove said.