DAVID GREENE, HOST:
And now a murder mystery of sorts. The scene of the crime: Everglades National Park. We already know the murderer: the giant Burmese python. The species has invaded Florida. The mystery lies in identifying its victims. As NPR's Rhitu Chatterjee reports, a forensics expert is on the case.
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RHITU CHATTERJEE, BYLINE: Carla Dove opens a small white box. She's sitting at a lab bench in her office at the Smithsonian Museum of Natural History.
CARLA DOVE: It's kind of like Christmas for me because I never know what's going to be in these packages.
CHATTERJEE: Inside are a bunch of sandwich-size Ziploc bags.
DOVE: One, two, three, four, five, six - eight. Eight samples today.
CHATTERJEE: Each sample consists of grayish pieces of feathers, and sometimes bones, all from inside the stomachs and intestines of Burmese pythons. These giant snakes are thriving in the Everglades and devouring local birds and animals.
DOVE: Let's look at this one first. This is python number 780. It was collected on the 18th of March 2013, so it's a recent one.
CHATTERJEE: Park officials are interested in the diets of these pythons because they want to know what native species might be threatened. Now, when it comes to animals, they pretty much know that the snakes eat rabbits, foxes, even alligators. They've often caught them in the act. But it's been harder to know what birds they've been snacking on. That's where Carla Dove comes in.
DOVE: We can see what's in here and go to work on identifying the birds that this nasty snake has been eating.
CHATTERJEE: Now, you can't identify the birds from their DNA because these half-digested remains are contaminated with snake DNA. So it's a question of recognizing the birds just from their feathers.
DOVE: Sometimes they are nice and complete feathers and I can recognize them right away.
CHATTERJEE: But often she has only tiny fragments to go on. She uses tweezers to pull a piece out from one of the Ziploc bags.
DOVE: Even though it's as tiny as the strand of hair, really, it could be enough to have some special diagnostic microscopic features that might help us determine if it's a heron or maybe it's a bird of prey or a pigeon or a dove.
CHATTERJEE: This piece is a downy bit from the base of a feather, what scientists call barbules. Dove places it gently on a glass slide and turns on her microscope.
DOVE: I'll let you have a look at this. In the middle of this slide there's a tiny piece of a downy barbule that has me excited.
CHATTERJEE: To me it's just a bunch of fine transparent needles with bits of color here and there. But Dove recognizes the pattern instantly. It belongs to a group of birds that includes cranes and rails. But...
DOVE: It's different from the rest of the birds that it's related to.
CHATTERJEE: She still has to confirm it, but she suspects the python's victim was a limpkin. Now, most days Dove spends her time investigating the remains of birds who've died in very different circumstances: birds who've crashed into airplanes, like the flock of starlings that brought down a flight off of Boston Harbor back in 1960. The crash destroyed the plane and killed most of its passengers.
DOVE: After the Boston crash, the airline industry started to get really interested in birds that are causing damage to airplanes.
CHATTERJEE: Most bird strikes don't cause crashes, but it's still really important to know what species was involved, so you can change flight paths or alter the airport environment or design stronger aircraft engines.
DOVE: Knowing the exact species of bird that is on your airfield and causing a problem is the very first step in trying to reduce this risk.
CHATTERJEE: And there's a huge demand for Dove's expertise. Just this past year, she processed about 8,000 cases, many of them involving military airplanes.
DOVE: We get a lot of samples from Afghanistan. That's because we're doing a lot of flying there.
CHATTERJEE: A few years ago, she solved the mystery of a large unknown bird that flew into a fighter jet at Bagram Air Base. Michael Begier is with the U.S. Department of Agriculture's Airport Wildlife Hazards Program. He was called in by the Air Force to help with the case.
MICHAEL BEGIER: There was several million dollars' worth of damage.
CHATTERJEE: Dove had identified the offending bird as a black kite.
BEGIER: The black kite is a raptor, but it's similar in size to some of the vulture species we have in North America.
CHATTERJEE: And it was up to Begier and his team to prevent such accidents from happening again. So they went out to Bagram Air Base and started looking for black kites.
BEGIER: One of the things we discovered was that trash disposal at the base was in a spot that brought the birds closer to the runway and to the flight path of the jets.
CHATTERJEE: Once the trash was removed, the birds disappeared. One of the reasons Dove is able to identify birds from anywhere in the world is because the Smithsonian Museum has a massive collection of birds. Dove takes me out into a climate-controlled hallway, stacked from floor to ceiling with cabinets.
DOVE: So this collection is like my library. This is my reference.
CHATTERJEE: The library has 620,000 specimens from all over the world. And in fact, Dove's work with the military in Afghanistan has added 80 new species to the museum's collection. But it's the python victims that are on her mind today. She wants to confirm that the fragment she saw under the microscope was indeed from a limpkin.
DOVE: Here we go to the limpkin drawer. Slide out the case door.
CHATTERJEE: She's in luck, because in addition to that fragment, the ziplock bag also contained a single intact feather. She holds it against the wing feathers of a very still, very dead bird that looks a bit like a browner, smaller version of a heron. The match is perfect.
DOVE: So I think we have solved this case. Python number 780 was feasting on a limpkin on 18th of March 2013.
CHATTERJEE: Dove's keen eye and knowledge of feathers has come from more than two decades of practice. And she's the only person in the country with these skills. But she worries about the future of this kind of analysis.
DOVE: Unless I have someone to follow me around and do some research on the microscopic structure of feathers, I think that one of these days the whole expertise in this field is going to go away.
CHATTERJEE: She inherited this lab from the only other person in the country who did this kind of work. But she says she has yet to find the person who will take over this unique feather forensics lab. Rhitu Chatterjee, NPR News, Washington.
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GREENE: The aptly named Carla Dove has determined that pythons like to snack on some 30 species of birds, including limpkins, mallards, egrets, herons and wood storks. To date, Dove has examined the remains on nearly 150 Burmese pythons. You can learn more about her work and also take a virtual tour of her lab by watching a slideshow at NPR.org.