Forensic Analysis

January 1, 2009 by Gregory Gough

On January 15, 2009, US Airways Flight 1549 hit several birds forcing it to land on the Hudson River after both engines failed. The courageous flight crew saved all 155 passengers.

Planes striking birds is not an uncommon occurrence. In 2007, more than 7,400 birdstrikes with aircraft were reported in the United States. At least 110 of those strikes caused significant damage. Since 1988, scientists estimate that birdstrikes have caused 229 deaths and destroyed 210 aircraft worldwide.

The Guilty Party

To mitigate future bird/airplane interactions, it's critical to determine which kinds of birds are involved in the collisions. Large birds are the ones most likely to cause damage and many of these types of birds have been increasing in number in recent years.

Two geese flying

The Feather Identification Lab analyzed feathers and tissue samples recovered from the plane's engines. Both DNA analysis and comparison of feathers with known samples fingered the culprit: the Canada goose (Branta canadensis).

Canada geese are big birds. They can weigh more than 10 pounds and their wings can span 5 feet across. Canada geese are a familiar sight. They live all across North America in local parks, golf courses, and wetlands—they like fresh water and they like lawns.

But despite their ubiquity, Canada geese are quite varied. Some subspecies are almost as diminutive as a mallard duck. And these different varieties have different ranges at different times of year, some are migratory and some are not.

A Second Look

To figure out which variety of Canada goose caused the damage, the old adage "you are what you eat" was employed. The food a bird consumes is what is used to build its feathers. A goose grows new feathers after it has molted, which it only does once a year, on its nesting grounds, and after raising young.

The raw ingredients of both food and feathers are familiar elements such as Hydrogen, Oxygen, and Carbon. Although they are found all over our planet (and throughout the Universe), there are subtle differences in the number of neutrons in their nuclii. The different variations of the elements are called isotopes.

These isotopes can be more common in certain areas. In the case of Hydrogen, the isotopes vary by latitude, there is a difference between polar, temperate, and equatorial regions.

The isotopes in the goose feathers were compared with known samples from birds that are resident in the New York area and those that nest in the Arctic and migrate to New York for the winter.

They most closely matched samples from Labrador, Canada thus indicating that the Canada geese involved in the collision were migratory geese, not the more common resident Canada geese.

Plane and cormorant flying

State-of-the-art forensic analyses helped determine the species and geographic origin of the birds involved in the crash of US Airways Flight 1549 and provided airport managers with important information to use in formulating strategies to reduce the risk of future bird/plane conflicts.

In the video below, Carla Dove and Pete Marra discuss the use of forensic techniques to identify birds.

This article summarizes the information in this scientific paper:

Migratory Canada geese cause crash of US Airways Flight 1549. 2009. Peter P Marra, Carla J Dove, Richard Dolbeer, Nor Faridah Dahlan, Marcy Heacker, James F Whatton, Nora E Diggs, Christine France, and Gregory A Henkes. Frontiers in Ecology and the Environment 7: 297–301.

Download scientific paper