current issue web exclusives blog multimedia archive subscribe advertisers
Feature Articles
Editor's Note
Audubon View
Field Notes
Green Guru
Citizen Science
Earth Almanac
One Picture

Feather Forensics
Carla Dove helps solve avian mysteries as head of the Feather Identification Lab at the Smithsonian Institution.

From left to right: Marcy Heacker, Faridah Dahlan, James Whatton, and Carla Dove.
Chip Clark, Smithsonian Institution

When US Airways flight 1549 went down in the Hudson River earlier this year, initially no one knew what kind of birds took out the plane. To identify the species, tissue and feather samples were sent to Carla Dove (yes, that’s her real name), who heads the Feather Identification Lab housed at the Smithsonian Institution in Washington, D.C. Her four-person lab has interagency agreements with the Federal Aviation Administration, the U.S. Air Force, and the U.S. Navy. Audubon recently spoke with Dove about how her lab is helping to make the skies safer for birds and planes, the recent birdstrike in New York, and how an airplane can hit a deer while flying at 1,500 feet.

Audubon: How did you get into this field? 
Dove: I came to work at the Smithsonian as a museum technician, and that’s where I met Roxie Laybourne, who was the pioneer of what’s now being called forensic ornithology. That was in 1989, and she was in her 80s at the time. So I started working with her and learning her techniques for feather identification. I went back to school and worked on my graduate degrees, both of them at George Mason University in Fairfax, Virginia, under Roxie’s direction, and the Air Force supported my position as her assistant. She passed away in 2003. She was 92, and she was still working until the very last months of her life. She was a character. In her day, and in a museum environment, she was a rare bird.

Q: Where do you get the samples?
A: We usually get the samples through the U.S. Post Office. They’re feather samples or bits and pieces of dried material that may or may not have any bird remains. Last year we did over 4,500 samples; that’s somewhere around 18 per day. It takes a minimum of an hour to do one identification, and some can take up to six days if we send them to the DNA lab. Our busiest times of the year, of course, are spring and fall migration, when we can get close to 500 samples a month. Over the past few years it’s been increasingly steady throughout the year. We don’t have very much downtime anymore.

From left to right: Marcy Heacker, Carla Dove, James Whatton, and Faridah Dahlan.
Chip Clark, Smithsonian Institution

Q: How do you go about identifying the samples?
A: Our typical day consists of opening the mail and sorting it into what kind of material it is. Is it whole feather? Is it a sample that’s been wiped off of an aircraft on a paper towel? Then we do triage. Basically, we have three tools. We have the whole feathers, which we can compare to the museum collection; we have the microscopic feather characters; and we have DNA analysis.

Q: Could you tell me a bit about each of those tools?
A: If we’ve got some whole feathers and they’ve got some color and some size and shape and texture, we’ll identify them using the specimens that we have here at the Natural History Museum. That’s usually the fastest and the cheapest way to do it. There are 10,000 species of birds in the world, and we have about 85 percent of that biodiversity represented in the collection. We have many individuals from different species, so we have somewhere around 620,000 museum specimens. That includes study skins and skeletons, eggs and nests, and specimens stored in alcohol.

Now, what if we just have a big brown feather? There are a lot of birds that have brown feathers. Roxie Laybourne looked at the microstructure of different groups of birds and determined suites of characters that set groups apart—like the shape of the node [a certain part of the feather], or the amount of pigment in the downy, fluffy part of the feather. So we have an idea of orders of birds based on a microscopic structure. If we know that big brown feather belongs to a bird of prey, we might compare it to the microstructure of some of the hawks and vultures, and then narrow it down.

If we don’t have anything except a blood smear, or what we call snarge, on a piece of tissue, then we will send that to our DNA lab. We’re collaborating with the University of Guelph, and they’re making a library of a small gene sequences called BoLD (Barcode of Life Database) that we use to match up our unknown sequences from birdstrikes. We have now a known DNA library of the birds of North America. We usually get a 99 or 100 percent match to the library, and then that’s sufficient for us to call it identified.

Q: Which birds do you usually see?
A: By far the most common birds are small birds, passerines, things like horn larks and barn swallows. Mourning doves are very common because of the habitat on the airfield—they like the grass seed, and they like to hang out on the flat areas. Killdeer like to nest on the pebbled areas. These small birds are usually non-damaging. When people have a birdstrike program on their airfield, and they are reporting a lot of small birds, then they are probably doing what they need to be doing to keep those big birds that do damage away from the airfield. Some people are hesitant to report birdstrikes because they fear that it looks like they have a problem, but that’s not the case at all. If you don’t report birdstrikes, we know you’re not doing something right because every airfield has birdstrikes.

Q: How does the data help prevent future birdstrikes?
A: We really strive to get that species identification because that’s the bottom line. Species differ on what they eat and where they like to hang out, how much they weigh, when they migrate, how they fly. For instance, in the Hudson River case, it could’ve easily been a brant, which is a goose that looks similar to a Canada goose and is also quite common in the region, but it weighs a lot less than a Canada goose. So for the purposes of the engine failure, we really needed to confirm that indeed it was an eight-pound bird that went into the engine instead of a three-pound bird or a four-pound bird.

When we get the remains, there is a report attached that has a unique number. Whenever we do the identification, we just go online, open up the report, and enter the identification. It goes immediately back to the person in the field.

Carla Dove picking 'snarge' from an aircraft part.
Chip Clark, Smithsonian Institution

The Air Force uses that data in a couple of ways. A copy of the report goes to the U.S. Air Force Safety Center, where they maintain a centralized database. They use the data to build bird avoidance models (BAM), for pilots to log onto and check what happened historically on their proposed route at specific times of year, at specific times of day, so they can get an idea of what the risks are before they even begin their flight. And then when engineers design new airplanes and new engines, they take the data on the weights of birds and design the aircraft and the engines to withstand a certain weight of bird at a certain speed, and improve aviation safety and aircraft safety by using that kind of data that accumulates over time.

But the main use, the on-the-ground use, is knowing what species are the culprits right away so they can change the habitat management on the airfield or move a pond, or do some kind of mitigation around the airfield to keep birds from being attracted to the area. Most birdstrikes occur on takeoff and landing, so if they can do something in that immediate area, that can really reduce the risk of birdstrikes.

Q: Do you ever find samples from animals other than birds in the snarge?
A: We find fish, we find frogs, we find deer. One time we had a cat. Sometimes we find birds that aren’t really supposed to be in North America. These are little puzzles that we have to explain, and we have to do more digging in these cases. For example, for the fish, we concluded that an osprey had a fish in its talons, and that’s how it got into the engine at 1,500 feet. Frogs and other small animals will get picked up on the runway; they can get sucked into the engines at takeoff. We really never found a good explanation for the cat, unless it was something a bird had eaten. We get bats because they’re up there flying around just like the birds.

Deer are hit on takeoff and landing. But we did have a puzzling deer strike recently. The sample was just a piece of cheesecloth with some blood wiped on it. We sent it to the DNA lab, and it kept coming back as a high match to deer. We said, ‘Well, the pilot could have hit a deer.’ So we called him and he said, ‘No I remember that strike and it hit the wing, it did like $8,000 worth of damage, and I know that we were at 1,500 feet.’ So we were like, ‘Okay, what happened here?’ It’s not like there are reindeer flying around out there. We went back to the sample, made a microslide from the sample, and we found some tiny barbules from black vulture. So we concluded that probably the black vulture had been feeding on a deer carcass, and when it hit the plane, the DNA from the deer was overwhelming in the sample. It keeps us on our toes for sure.

Q: It seems like the DNA technology is very important. Does it supersede the older techniques?
A: No. The kind of apprenticeship-type training that I got from Roxie is still important because we don’t get DNA from every sample; some of the samples are degraded, and some of them don’t have blood or tissue associated with them, so we still need to use the microscope and the morphology of the feathers. I’m starting to be a little concerned because the support isn’t there right now to train someone to come in and take over. I still have some time left, but not that much. I’ve been here 20 years and it took me about 10 years to really be confident on the microscope. I hope in the near future we can get some funding for a new person who can start learning and carry on this work.

Q: What else does your lab do?
A: We’re working with a biologist in the Everglades, Skip Snow, who is examining stomach contents from Burmese pythons that have established themselves in the Everglades and are wreaking havoc on the native bird populations there. By providing him with the bird species that these snakes are eating, he’s able to say, “Hey, this is really important and we need to figure out how to control these snakes.” It is, after all, an invasive species, and they’re eating a lot of native birds and animals that are threatened and endangered in the state. We also do work with the anthropology department here at the Smithsonian identifying anthropological items that have feathers on them. But most of our work involves birdstrikes.

Q: Your lab confirmed that a Canada goose caused the crash in New York in February, right?
A: Yes. That was the one birdstrike that everybody predicted for 20 years, and luckily nobody was killed. We dodged a bullet. But birdstrikes are very common, and in North America there are a lot of large-bodied birds, like bald eagles, turkeys, pelicans, and cormorants, whose populations have increased significantly over the last 25 years. With more really big birds flying around, and more airplanes flying around, the probability of something like this happening goes up. We don’t have that quantified, but it’s just common sense. There may be increased danger because of those factors, so we hope that by identifying birds and getting that information back to the field, we can prevent something like the Hudson River crash from happening again.

Back to Top

Back to Web Exclusives

Related links: “Clearing the Air