An analysis of feathers and DNA found that the birds were migratory and probably wintering in New York. At least three struck the plane's engines, forcing a landing in the Hudson River.
Canada geese hold formation as they glide in for a landing in the San Pasqual Valley. Canada geese fly thousands of miles from the northern U.S. and Canada to warmer climates during the winter. (Don Bartletti / Los Angeles Times)
Chemical analysis of feathers has confirmed that the birds that caused US Airways Flight 1549 to crash-land in the Hudson River in New York were migratory Canada geese, researchers from the Smithsonian Institution reported Monday.
The Airbus A320 collided Jan. 15 with a flock of birds about 2,900 feet above the ground and about 5 miles from LaGuardia Airport, where it had taken off. Both engines were damaged, but Capt. Chesley B. Sullenberger III managed to land the plane in the river with only minor injuries to some of the 155 people on board.
Samples of bird feathers and tissue were sent to the Feather Identification Laboratory at the Smithsonian's National Museum of Natural History, which routinely identifies birds involved in aircraft collisions.
About 7,400 such bird strikes are reported to the Federal Aviation Administration each year, but the real number is far higher: The FAA estimates that only 20% are reported. Bird strikes have destroyed 210 aircraft and caused 229 deaths since 1988.
Remains from about 4% of the reported strikes are sent to the Smithsonian for identification, according to Carla J. Dove, the lab's aptly named ornithologist.
In the case of Flight 1549, the feathers were compared to museum exemplars and found to be structurally identical to those of Canada geese (Branta canadensis), an identification that was confirmed by DNA analysis, the team reported in the journal Frontiers in Ecology and the Environment. The birds weigh about 8 pounds, more than enough to cause heavy damage.
The researchers then went one step further and examined the ratios of hydrogen and its stable isotope, deuterium, in the feathers. Studies of migratory birds have shown that the deuterium/hydrogen ratio can be used to identify where the birds molt and breed: The higher the ratio, the further north the birds were when they grew new feathers.
"This is the first time we've ever done anything like this" to identify bird strikes, Dove said. The analysis showed that the birds were Canadian migratory geese that bred in Labrador. They may have been wintering in the New York area.
"Knowing that the birds were migratory is crucial to developing management strategies," said ornithologist Peter P. Marra of the Smithsonian Migratory Bird Center, another author of the paper.
If the birds are local, he said, tactics such as population reduction and habitat modification can reduce the number of bird strikes. But if they are migratory, then improved radar technology and other techniques would be more appropriate.
"Birds and planes share airspace," Marra said. "We need to figure out how to play nice."
The team is approaching the more complicated task of trying to determine how many birds struck Flight 1549. A preliminary DNA analysis shows that "at least one male and one female struck one engine, and at least one female struck the second," Dove said. "That corroborates what the engineers thought."
The National Transportation Safety Board will open hearings today about the US Airways incident and other bird strikes.
source: http://www.chicagotribune.com/news/nationworld/la-sci-birdstrike9-2009jun09,0,226718.story
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