Tuesday, June 09, 2009

US Airways Flight 1549 Collided with Migratory Geese

The Smithsonian Institute's Feather Identification Laboratory has determined that US Airways Flight 1549 struck a flock of migratory Canada Geese before its crash landing in the Hudson River.

Researchers in the Feather Identification Laboratory at the Smithsonian's National Museum of Natural History used molecular genetic techniques and feather samples from museum collections to determine that the birds involved were Canada geese (Branta canadensis). This is one of the largest species of birds in North America, and the individual birds involved are estimated to have weighed about 8 pounds....

The team took their research to a molecular level at the Smithsonian's Museum Conservation Institute labs in Suitland, Md., where they examined stable-hydrogen isotopes from the feathers to confirm whether the geese were from resident or migratory populations. Stable-hydrogen isotope values in feathers can serve as geographic markers since they reflect the types of vegetation in the bird's diet at the time it grew new feathers after molting. Using a mass spectrometer, which measures the masses and relative concentrations of atoms and molecules at high precision, the scientists compared the bird-strike feather samples with samples from migratory Canada geese and from resident geese close to LaGuardia Airport. Analysis revealed that the isotope values of the geese involved in the crash of Flight 1549 were most similar to migratory Canada geese from the Labrador region and significantly different from resident feathers collected in New York City.
To be clear, this finding does not necessarily mean that the geese in question were migrating at the time of the incident. Instead it means that the geese had bred somewhere north of here – possibly Labrador, possibly someplace else – and migrated to the New York area to spend the winter. This is a normal phenomenon; each winter our resident breeding flocks of Canada Geese are augmented by migratory flocks of Canada and Cackling Geese.

I had thought that if Canada Geese were the culprits, the birds in question would be resident geese, simply because they are so ubiquitous. But in a way, this finding is not surprising. Resident geese are more likely to know the landscape well and have a better sense of the activity and flight paths around area airports. They are thus in a better position to know what areas to avoid so that they do not run into airplanes. Migratory geese, meanwhile, have to learn the area from scratch (or recall it from previous visits), so they may be less aware of potential dangers. I do not know how well geese can apply such knowledge, but it would not surprise me if it were operative in some form.

The Smithsonian scientists hope that their research will help wildlife managers and aviation officials decide how best to prevent such collisions in the future. This type of isotype analysis may also have applications for studying bird strikes on other objects such as communications towers and wind turbines.