Snarge. The snarge arrives at the Feather Identification Lab by the armful—20 manila envelopes a day, some 6,600 envelopes last year alone, converging here from airports in all 50 states for scientific analysis. You open an envelope and out slides a gallon-size Ziploc bag, sometimes with a gorgeous owl or duck feather sealed inside, but all too often with a bloody paper towel or charred bits that, after a trip through an airplane engine, look like something scraped off a barbecue. Textbook snarge.
Snarge, the feather lab’s lingo for “bird ick,” results from so-called bird strikes—midair collisions between flying machines and fowl of all sizes. A hummingbird might leave a lipstick smear on the fuselage; a duck might dent a wing; a pelican can take out an engine and bring down a plane.
Pilots don’t know what they hit when they hit it, only that they felt a thwump. After landing, they wipe the bird purée off and ship it to the Feather Lab, located in a cozy four-desk office in the National Museum of Natural History, to find out what it was.
The lab—run by the Smithsonian with support from the Air Force, the Navy, and the Federal Aviation Administration—is headed by the fortuitously named Carla Dove, who wears a blond bob and smiles easily despite her macabre profession. Dove trained as an ornithologist—although, she laughs, “there really was no way to prepare for this job.”
She and her team first try to identify the snarge in each envelope with the help of any whole feathers. But the feathers often arrive in tatters, and for some of the really snargey samples, few feather bits remain.
That’s why Dove’s lab has joined a growing number of federal agencies in embracing a new technology called DNA barcoding.
Every living thing contains DNA, a long, thin molecular helix that produces the proteins and other biomolecules that make us go. Each species has its own DNA sequence—a unique structure of the four chemical “letters” that DNA uses (abbreviated A, C, G, and T, which stand for adenine, cytosine, guanine, and thymine). DNA barcoding uses one small stretch of DNA in each species as a biological tag, much like the universal product code on groceries.
Barcoding is notable for being one of the first practical applications of genetic sequencing, which has made stunning progress in the last decade. And as the cost of sequencing continues to plummet, barcoding has become indispensable even in fields that seem remote from molecular biology.
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The Human Genome Project, which wrapped up around 2003, occupied hundreds of scientists for more than a decade and cost billions of dollars. Most researchers had hoped that mapping the human genome would revolutionize medicine. That hasn’t happened yet—it will likely take a few more decades—but the project did help foment another revolution in biology.
Top DNA-sequencing machines now cost a mere $100,000 and can generate more data in 24 hours than the Human Genome Project did in its first ten years. “Sequencing DNA is now like sending off a roll of film used to be,” says David Schindel, director of the Smithsonian’s Consortium for the Barcode of Life, based at the National Museum of Natural History.
DNA sequencing has become routine, almost mundane. But for exactly that reason, the best minds in science can now concentrate on applying what they’ve learned about DNA to bigger problems, and barcoding has emerged as one of the more promising applications for both pure research and commercial industries.
Dove and her team at the Feather Identification Lab use barcoding in 80 percent of their cases, allowing them to identify almost 100 percent of the specimens they see, even those that are little more than red-crusted paper towels and organic tar. Barcoding has also helped the lab to identify species that are not birds. Planes clip bats all the time, and occasionally smack deer and raccoons, too, because most strikes happen on takeoffs or landings. Dove has even located fish remains on planes—presumably from the mouths or stomachs of unlucky birds.
The information gleaned from barcoding helps pilots, airport officials, and airplane engineers identify what species of birds cause the worst strikes. Dove’s team used DNA to finger the culprit (a red-necked phalarope, a shore bird) when a bird strike over California grounded Vice President Joe Biden’s Air Force Two in April. Barcoding also assists forensic investigations when those strikes lead to crashes. After US Airways Flight 1549 crashed into New York’s Hudson River in early 2009, every bit of organic gunk that biologists could scrape off the hull went to Dove’s lab.
Barcoding identified the culprit in the accident as the Canada goose, a finding confirmed with feather samples. Dove’s lab extracted both male and female DNA from the remains sucked into the engine, proving that at least two geese had brought the plane down. In the end, her team determined that it was probably a gaggle of geese—cruising along in a V high above New York, never suspecting their final destination would be a plastic bag on a desk in downtown DC.