Call it CSI: Bird Strike. For the first time, researchers have used a sophisticated chemical analysis to finger the fowl that brought down an airplane. The case? Figuring out just which type of bird caused a US Airways jet to crash into New York's Hudson River in January.
Shortly after taking off on 15 January from LaGuardia Airport in New York, the engines on US Airways Flight 1549 failed when the plane encountered a flock of birds. In what was hailed as testimony of pilot prowess, the pilot glided the plane onto the Hudson River, with no loss of life. Federal investigators collected 100 samples of tissue and feather remains from the engines, then sent them to the Smithsonian Institution's Feather Identification Lab in Washington, D.C.
Large waterfowl were the top suspects, as plane engines are designed to withstand strikes from smaller birds. "It is really critical" to know what birds are involved, as airports need permits and programs to deal with birds that get in the way, says Sandra Wright, who manages the federal bird-strike database at the U.S. Department of Agriculture (USDA) in Sandusky, Ohio. In 2007, there were more than 7400 bird strikes documented in the United States, and many thousands more go unreported. Since 1988, worldwide, bird strikes have caused 229 deaths and destroyed more than 210 aircraft. They cause an estimated $1.1 billion in damages each year.
To narrow down the suspects in the US Airways crash, the Smithsonian lab's Carla Dove isolated and sequenced a small piece of a mitochondrial gene--known in the field as a DNA bar code. By comparing that sequence with a known database of bird bar codes, she learned that Canada geese were the culprits, one of two prime suspects. Dove routinely determines the bar codes to identify birds involved in bird strikes, but this time, she went one step further: She wanted to figure out where the geese came from.
To do that, Dove tapped Peter Marra, an ornithologist at the Smithsonian Migratory Bird Center in Washington, D.C. Marra studies bird migrations in part by doing a sophisticated chemical analysis of feathers. Using mass spectrometry, he measures concentrations of stable isotopes, such as hydrogen, which vary from one region of the continent to another. They are consumed as part of the birds' diets and can reveal breeding grounds.
Marra and his colleagues first determined the hydrogen isotope profile of feathers from museum specimens collected from Labrador and Newfoundland, Canada. They also looked at the profiles from Canada geese that live year-round in New York City. The isotope profile of the feathers inside the jet engines matched that for the Labrador birds, the team reports online today in Frontiers in Ecology and the Environment. These birds were likely wintering in balmy New York but were on the move again because of a recent snowstorm in search of open fields, says Marra.
"This information has broad implications for wildlife management," says Michael Begier, a wildlife biologist with USDA in Washington, D.C., who advises airports about reducing bird strikes. Often, he says, airports take steps to clear resident geese from areas surrounding airports. That migratory birds were to blame in this crash suggests that more research needs to be done into bird-detecting radar or other onboard strategies to prevent hits, says Begier.