Johns Hopkins Magazine -- February 1997
Johns Hopkins Magazine




Bill Seegar fell in love with falcons as a boy, through the King Arthur legends. Now he and a crew of wildlife biologists are taking the study of these birds from the dark ages of banding to the microelectronics revolution.
S C I E N C E    &    T E C H N O L O G Y

Raptor Romance
By Melissa Hendricks

ON A BRILLIANT AUTUMN MORNING, a worn Chevy Blazer pitches and rolls, heading south, across a desolate stretch of beach on Assateague Island. Three pairs of eyes inside the truck scan the seam between bleached sand and bluebird sky. At the wheel, a tall man named Bill Seegar is telling a story, while in the seat beside him, his assistant, Jimmy Dayton, holds a lure embroidered with nooses. Abruptly, Seegar stops his story.

"Hawk at 3 o'clock. Hold this," he blurts, handing Dayton a cup of coffee. He turns the truck around, and people and papers, cell-phone and knapsacks sail across the seats. The Blazer races westward toward a hillock 200 yards away. In the distance, the object of Seegar's desire, a peregrine falcon, takes flight. Seegar throws the baited lure high up out the window, and speeds away. The falcon swoops once, twice, then lands a few feet from the lure.

The people in the truck hold their breath as the falcon eyes the bait. Then, not a hundred yards from the falcon, a swimmer emerges from the sea. "A nudey," mumbles Seegar nervously. "Don't go near the bird!" The falcon looks up. The nude man starts jogging southward along the beach. In a heartbeat, the falcon is gone.

"Goddammit! We had that bird. Goddammit!" shouts Seegar. He stomps on the accelerator and resumes his drive southward, shoulders hunching forward, and eyes combing the dunes for another chance.

BILL SEEGAR (PhD '77), A BIOLOGIST WITH THE U.S. ARMY, directs a team of wildlife biologists and naturalists who catch, band, and release tundra peregrine falcons every autumn on Assateague, a barrier island along the Maryland-Virginia border. The birds migrate south from breeding territory in the tundra regions of Greenland, Canada, and Alaska to wintering grounds in Central and South America, and Florida. Falconers discovered the migration through Assateague in 1938, and the Army began banding and surveying tundra peregrine falcon there in the late 1960s.

Banding and surveys help biologists monitor flux in the peregrine population. It was through such methods that falconers and biologists discovered the drastic decline in peregrine during the 1940s through 1970s, which was eventually linked to the pesticide DDT. Though DDT has been banned in the U.S., and the tundra peregrine falcon (the subspecies Seegar studies) has rebounded, new pesticides and destruction of critical habitat now loom as threats. The biologists remain on the lookout, and conduct their survey zealously. A missed bird is a cursed blunder.

But banding reveals only a snapshot of the range of a peregrine, which can fly 10,000 miles in one migration. Where does a bird banded in Assateague in the fall spend the winter? Where does it stop along the way? Banding and surveys leave many questions.

Now Seegar is poised to solve many of those mysteries. He holds the answer in his hand, in the form of a gold-colored box the size of a Matchbox car. The device, he says, is taking the study of peregrine falcons from the dark ages of banding to the renaissance of the microelectronics revolution.

It takes about 45 minutes to equip a peregrine falcon with the satellite transmitter that will allow the team to track its migration southward. Each transmitter costs between $2,400 and $2,900, so the researchers use them sparingly.
The instrument is a transmitter that communicates with satellites. When fitted to a bird, it informs Seegar's team of the falcon's location anywhere on the globe. "It is like the Manchurian Candidate," he says. "You know where the bird is all the time."

The platform transmitter terminal (PTT), as the device is formally called, is a souped-up version of a prototype developed at the Johns Hopkins Applied Physics Laboratory (APL). Though it weighs a mere 20 grams (0.7 ounce), it contains some of the world's most sophisticated microelectronics. The team has placed about 60 of the devices on peregrines, and in just a few years, the transmitter has provided more information about the migration and distribution of peregrine falcons than biologists had learned in the preceding decades, says Seegar.

Through a U.S. Department of Defense program, the researchers have also placed the instruments on a dozen other species including eagles, pelicans, horses, and even a type of antelope called oryx. The transmitter can help show where an animal goes, which species it interacts with, and, in particular, how people affect its well-being, all useful information for resource managers.

In perhaps its most dramatic demonstration, the transmitter was used to pinpoint the cause of a mysterious and precipitous decline in the population of Swainson's hawks from breeding grounds in Canada and the western U.S. Scientists tracked several of the equipped hawks to wintering grounds in Argentina, where they discovered thousands of the dead birds. The hawks had perished by consuming grasshoppers laden with the pesticide monocrotophos. Faced with this information, Argentina has since banned its use on certain crops, and manufacturer Ciba-Geigy is changing its labeling. This demonstrates, Seegar says boldly, that the transmitter is changing the face of wildlife biology.

Part Indiana Jones, part Robin Williams, Seegar can talk the chicken off the bone when he's onto something he cares about. With his towering frame, mantle of silvering hair, and fondness for bold neckties, he stands out at meetings of gray-suited academics like a cardinal among starlings.

Seegar fell in love with peregrine falcons as a boy, through the King Arthur legends. His boyish enthusiasm often still surfaces, as when he says his work with falcons is "a really cool thing to do," though now his interest is charged with a sense of mission. "Every place migratory birds land is critical habitat," he says. "They've got to forage for insects, seeds, shorebirds. If we develop that land--build an asphalt parking lot on a marsh--we'll wipe it out. Using this technology, we're fighting the war on preserving avian species in this hemisphere. We're going to lose it, we're going to lose it badly. We need to figure out how we can save species, and do the best we can."

Where Seegar is electricity, Jimmy Dayton (center) is equanimity--an all-around Mr. Fixit, the straight man to Seegar's jokes, observed writer Melissa Hendricks (right).
Where Seegar is electricity, Jimmy Dayton is equanimity. Balding, with a neatly trimmed red moustache, Dayton is reliable, Seegar's all-around Mr. Fixit, and the straight man to his jokes. Dayton has been a hippie, master carpenter, logger, and organic beef farmer, and is now the program manager for the transmitter project.

Mike Yates, a raptor biologist at the Raptor Research and Technical Assistance Center, in Boise, Idaho, also came from another line of work. He was a lending and collections agent who lived for the times he could shed his suit and tie and go birding, when the team offered him a job. He is a rough-shaven, imposing figure, who, in another life, might have worn an eyepatch and carried a parrot on his shoulder.

Team member Linda Schueck was on a path toward a military career when she stumbled across the research of the falcon team. She is now a biologist at the Raptor Center.

For several weeks each autumn, these four, and intermittent others, come together on Assateague. They live in a former U.S. Coast Guard station and spend their days, from sunup to sundown, making rounds of the 37-mile- long island in two trucks, and luring in falcons and banding them. It is customary for Seegar to drive one truck, and Yates the other. The two men engage in a friendly rivalry to see who can catch the most birds. In a day, together they will catch from zero to two dozen falcons.

The team is amoeba-like. Anyone who provides a service that helps the researchers conduct their work is enveloped, and earns a seat in one of the trucks. The motley crew includes wildlife biologists, falconers, artists, a photographer, a mechanic, and hangers-on, all drawn together by the magnetism of the falcon.

And for a few days in early October, I am allowed to tag along as well.

EVERY HOUR SEEGAR'S TEAM SPENDS on Assateague is precious. A migrating peregrine falcon stays on the island only about 35 hours. "You have to be fast to catch falcons," says Seegar, as he drives along, scouring the dunes. "If you don't move fast, you don't catch birds."

The tundra peregrine falcon, Falco peregrinus tundrius to biologists, flies faster than anything on the beach, reaching speeds of up to 75 mph in level flight, and faster when diving. "When flying, they look like a teardrop, the most aerodynamic form," says Seegar. These birds of prey can climb several hundred feet, turn around, dive downward while accelerating, and pull up just in time to snag a shorebird. The designers of the F-16 jet supposedly studied the peregrine falcon to learn its aerodynamic secrets.

Adult tundra peregrine falcons are crow-sized, with long, pointed wings, slate-gray heads and backs, white breasts, and black-barred or dappled bellies and legs. Their eyes encompass a third of their heads, and they seem to watch you with an unflinching self-confidence.

For all their regality, the Einstein of the bird world they are not. "Does Gomer Pyle mean anything to you?" quips Seegar. "They're dumb, but they sure go like stink." Their edge in the hunting world comes from speed, Top Gun flying skills, and keen vision.

Unfortunately, the peregrine's perch at the top of the food chain has also been its vulnerability. Peregrine falcons are extremely susceptible to DDT, a chemical that clings to fat tissue. Insects eat plants laced with DDT, small birds eat the insects, and by the time large birds eat the small birds, they get a walloping dose.

DDT inhibits an enzyme that reinforces eggshells with calcium, causing thin shells that often break before hatching. By the 1970s, the eastern population of the subspecies Falco peregrinus anatum had been wiped out, in large part due to DDT, and the tundra peregrine falcon was an endangered species.

Since the ban on DDT in the U.S., the tundra peregrine falcon has rebounded, and was recently removed from the endangered species list. (F. peregrinus anatum remains endangered.) The fate of peregrine falcons and other raptors is far from certain, however. DDT is still used heavily in many developing nations. Pesticide use is climbing in the U.S. and throughout the world, according to the American Bird Conservancy.

Seegar likes to say that he is "like a doctor with his finger on the pulse of a patient." By studying predators such as falcons, he says, "we glean an enormous amount of information about the prey they eat. Going to where predators go, we can identify an area that's good for prey." Peregrines may be like the proverbial canary in the coal mine.

Seegar grew interested in peregrine falcons long before he had even heard of DDT. "They always made me wild," he says. "Ever since I saw one in a book when I was 11, I knew I was going to study them." At Hopkins's School of Hygiene and Public Health, he studied the closest thing he could find to falcons--swans, or, specifically, the life cycle of a swan heartworm. He earned his PhD in pathobiology under the tutelage of William Sladen, now professor emeritus.

Later, as a NATO research fellow at Oxford University, Seegar met Paul Howey, a waterfowl biologist with a bent for electronics. Howey had invented an electronic egg that contained sensors for temperature, humidity, and position. Placed in a nest, the "Trojan egg" would reveal the microclimate required for hatching. Raptor biologists had been trying to raise peregrine falcons, but they were having trouble hatching eggs in incubators. Seegar and Howey decided to use the electronic egg to measure the conditions under which peregrines hatched in the wild.

Off they went to a region of rocky cliffs frequented by nesting peregrines, in southwest Scotland. They planted their egg in a peregrine's nest, and retreated to a trailer to collect the data remotely. While the mother peregrine brooded, the scientists waited. And waited.

From boredom novel ideas are sometimes born, and so it was with the young biologists. Among other things, they discussed the migration of peregrine falcons.

No one had ever followed a peregrine to its wintering destination. So Seegar and Howey cooked up a plan using transmitters and satellites.

For several weeks each autumn, a former Coast Guard station on Assateague Island is homebase for Seegar and his team of wildlife researchers. They work from sunup to sundown banding falcons.
Back in the States, a friend named Joe Brennan who was a lawyer for APL urged Seegar to discuss his idea with engineers at the lab. In 1981, Seegar, by then a research scientist at the U.S. Army Edgewood Research Center, in Aberdeen, Maryland, proposed what he describes as a "naive request"--to a group of APL engineers.

Seegar asked the engineers--among them Joe Wall, Harold Black, George Weiffenbach, and Stanley Mantel--if they could build a satellite transmitter small enough to fit on the back of a peregrine falcon. To allow the bird to fly unimpeded, the transmitter could weigh no more than 5 percent of the bird's weight--for an adult male peregrine (one-third smaller than a female) that would be about 20 grams. At the same time, to communicate with a satellite, the transmitter would have to generate at least a watt of power.

The engineers looked at Seegar with raised eyebrows. They had invented Transit, the first satellite navigation system, for the Navy. But Transit tracked submarines, where weight was less of a constraint. Using satellites to track peregrine falcons was like something out of a James Bond movie. However, APL had been pioneering ways to shrink electronic components. So the engineers took on the challenge, soon joined by Howey, who had accepted a research position at APL.

AT ASSATEAGUE, SEEGAR ANGLES HIS TRUCK inland from the beach. Ahead on a dune a tall man carrying a pair of binoculars is waving. "That's Dave Hallenbeck," says Seegar. "He probably knows as much about falcons as anyone." When Hallenbeck is not teaching math at the University of Delaware, he walks the beach, neck craned backward, in search of falcons.

As we pull up alongside Hallenbeck, he tells us he just saw a passage tiercel, falconers' term for an immature male bird, and earlier in the morning saw a haggard falcon, a mature female bird. The tiercel flew inland, he says. He declines an invitation to ride in the truck, preferring to walk so he can scan the sky.

Seegar continues inland, in the direction of Hallenbeck's tiercel. With a little prodding, he picks up the thread of his story.

After his "naive" request, the APL team identified a satellite system called Argos-Tiros that was used mainly for weather forecasting, which could potentially receive signals from a bird-borne transmitter. They built a transmitter that weighed about 180 grams--not small enough for a peregrine falcon, but an appropriate weight for larger birds. The transmitter would beam radiowave signals up to a receiver on Argos, which would periodically relay the transmitter's frequency down to tracking stations on the ground. The Doppler shift of the radiowaves would reveal the location of the transmitter/bird.

On an autumn day in 1983, the scientists strapped the first transmitter onto a mute swan on Maryland's Chesapeake Bay, and released the bird. "As the bird took to the runway, you could hear running, and then you didn't hear it," says Seegar. "I cannot impress upon you how extraordinary it was. We had translated a dream into a reality. Science wasn't going to be the same."

During the next several years, the team tested the transmitter on trumpeter swans, golden and bald eagles, and giant petrels. Then Howey spun off his own company, Microwave Telemetry, Inc., in Columbia, Maryland (which now manufactures the transmitters for the team), and worked on miniaturizing the transmitter. He substituted an integrated design for one that used modular components, and incorporated a microcomputer to direct many functions. By 1993, the transmitter weighed only 27 grams.

It was ready for testing on a female peregrine falcon.

Seegar stops talking to look through his binoculars, and the roar of the sea fills the momentary silence. "There's one," he shouts, pointing to what looks like a stick angled in the sand a quarter mile ahead.

This time, the drill goes as planned. Seegar speeds up to the falcon. The bird takes flight. Seegar tosses out a baited lure, and backs away the truck. The falcon swoops and is snagged. Seegar sprints toward the bird, places a large hand on its back, and unsnags its talon. In a few minutes, he is holding an adult female, his hands wrapped around her legs and wing tips.

"They're beautiful birds," he says, smiling and holding her up proudly as though she were a miniature Venus de Milo. Indeed, the falcon stays still as a statue. Seegar presses his nose close to her back, and inhales. "She smells like the Arctic," he says. Her feathers are surprisingly soft. Not fluffy, like down, but smooth and luxurious like velvet.

Teflon ribbons looped over the falcon's shoulders and under the wings keep the 20-gram transmitter securely attached.
This bird will not carry a satellite transmitter, but Seegar uses her to illustrate how the fitting is done. The transmitter rests on the back of the bird, he explains, and is secured by Teflon ribbons that are looped over the shoulders and under the wings. It must be affixed just so, not tight enough to discomfort the bird and not so loose that it could detach. As far as Seegar knows, no falcon has been hurt by carrying a transmitter.

Today, the researchers only band the birds. (They will fit three adult peregrines with satellite transmitters next week, after I have gone. Each transmitter costs between $2,400 and $2,900, so the scientists use them sparingly.) Using pliers, Seegar places a band around the haggard falcon's ankle. Dayton swabs her breast with picric acid, an innocuous yellow paint that allows the scientists to avoid recapturing banded birds. The paint wears off in several weeks. Finally, with an upward arc of his arms, Seegar releases her.

A falcon flying on a moonlit night over the hook at the southern end of Assateague would see acres of marsh grass and dunes, crisscrossed here and there by narrow channels that wind from ocean to bay. Tucked in the middle of it all sits a solid, weathered house, the old Coast Guard station. Some 100 years ago, the falcon might have seen rescue workers rushing from the house to save passengers from a ship downed at sea. On this night, though, an aerial view reveals no commotion, just an electric blue glow through one of the downstairs windows.

The light emanates from a computer screen in the living room, where Seegar, Dayton, and Yates hover over Schueck while she taps at the computer's keys. Nighttime is not quitting time for the falcon team. They repair their lures, log the day's catches, and tinker with new software programs for mapping falcon sightings. It's also a nightly ritual for Seegar and Yates to rib each other about how many falcons they caught that day. Inevitably, Yates wins, in quality if not in quantity. "He'll catch more," says Seegar, "or if we get a passage tiercel and a passage falcon, he'll catch a passage tiercel, a passage falcon, and a haggard falcon."

While Schueck scrolls through maps and lists of peregrine data, Seegar talks about how the transmitters have enabled his team to connect the dots of what had been a sketchy outline of peregrine falcon migration.

For the first time, researchers are able to track the migration of male tundra peregrine falcons. This map shows some of the first data from a male peregrine. Bird #5696 was fitted with a transmitter on April 22, 1996, on Padre Island, Texas.
For example, biologists had long believed that Padre Island, Texas, was a critical landing spot for peregrines on their northward flight in the spring. Seegar's team confirmed this. "Padre Island is one of the most important areas for the peregrine falcon," says Seegar. "It constitutes their only known staging area--a place where they hang around for a couple of weeks while their hormones change and they put on weight," in preparation for a quick northward journey. This information comes soon after American General Corporation sought to build a large condominium complex, resort, marina, and golf course on the island. The company failed to pass certain legal requirements for the plan, but may try again.

The biggest mystery has been where the adult males go during migration. You can spend the entire autumn on Assateague and never see one. Yates's theory is that they have a different migratory strategy. "I think they make the trip in half the time, eat while flying, and fly over the ocean." So far, the transmitter data from a small number of male birds appears to confirm this theory.

"We find the adult males are coming down much faster," says Seegar. While a female will take 10 to 14 days to fly from Assateague to the Dry Tortugas, males make the trip in just four days.

A big unknown is the range and behavior of peregrine in their wintering territory. Peregrine falcons spend about half their time in the tropics and neotropics, where the Swainson's hawk story could be repeated for them.

There is a lot more the scientists want to know, and Seegar is buzzing with plans. He would like Howey to develop an even tinier transmitter, small enough for use on shorebirds. At APL, biomedical engineer Protagoras Cutchis has started to incorporate into the transmitter acoustic sensors and a miniature video camera--so Seegar's crew will be able to see and hear as if through the eyes and ears of their birds.

BY THE TIME FIRST LIGHT HITS THE HORIZON the next morning, Seegar has cooked up a mess of eggs and scrapple, and is chattering away, oblivious to the ungodly hour. We scarf down the food, climb into the trucks, and head out, stopping briefly to pick up wildlife photographer and sometime team member Michael Colopy.

"I love that stuff, adrenalin," says Seegar, as he heads north. "It was a great invention." Rivers of adrenalin flow through the truck this partly cloudy morning.

Almost immediately, Seegar and Dayton catch an immature female falcon. Within 20 minutes, they have caught another bird, and then another. Throughout the morning and halfway through the afternoon, they catch, band, and release falcons. The day takes on a sort of manic rhythm, with long stretches of driving occasionally interrupted by dramatic chase and catch episodes. "It's like fishin' in the sky," says Seegar. And so it is, with the same promise of climax teasing those who will submit to even-keeled stretches of time.

During the lulls, Seegar resumes the tale of the transmitter where he left off yesterday: in mid-October 1993, when the transmitter was ready to be tested on the first peregrine falcons. On a clear day on Assateague, Seegar harnessed satellite transmitters onto two adult female peregrines and released the birds.

During the next several weeks, the scientists saw that their experiment was working. With each blip of transmitter data beamed down through Argos-Tiros, they traced the course of the birds. One made a beeline for Cuba, and was never heard from again. The other bird kept transmitting. It flew to Guatemala, Honduras, Nicaragua, Ecuador, Bolivia.

"She got into the Andes, the headwaters of the Amazon," continues Dayton. Finally, in December, the falcon arrived in the high plains of Argentina, and there she stayed. Her signals came from a region in the Argentine altiplano, or high plains, about 700 miles northwest of Buenos Aires. The strange thing was that the falcon appeared to be in a salar, a treeless salt desert, an area so barren that the rare visitors who venture there say they start yearning for a "green fix."

Back in Aberdeen, the researchers were mystified. "Everyone had assumed that these birds winter in a marine environment," says Dayton. But this bird was 13,000 feet above sea level. How could a falcon survive there? What would it eat and drink? "It didn't make sense for her to be up there," says Dayton. So he agreed to go to Argentina to find her.

Dayton flew to Salta, in the foothills of the Andes. Transmitter signals indicated that the bird was about 250 miles southwest, as the crow flies. Dayton had only a crude map of the region, which showed salt deserts sprinkled among mountains with ominous-sounding names like Salar del Hombre Muerto. The last signals had come from the 3-by-70 mile Salar de Antofalla.

Joined by a biologist from Washington State, Dayton rented a two-wheel-drive truck and drove up to the arid, wind-swept altiplano. It was slow going. A foot-thick layer of ash and pumice from now-inactive volcanoes blanketed much of the region, and the road consisted of a double-wide bulldozed track through the ash. The men drove for three days, and then came to a point where they could forgo the bulldozed road and make a beeline through a salar. "We drove out about 200 yards, and sank down to the frame," says Dayton.

Since they hadn't seen another vehicle in two days, the only thing to do was to try pulling the car out of the pumice. "We got enough stones together so we could make a little road," says Dayton. "We'd dig a hole under a wheel, jack up the car, put stones under the wheel, let it down, go around and jack up the other wheel, and do the same thing. Then we'd back it up, go another truck length, the truck would fall through, and we'd do it all over again.

"We did that from 9 a.m. one morning until 5 o'clock in the afternoon the following day." Weak with altitude sickness, the men worked at a snail's pace. By the end of the second day, they had moved the truck only 150 yards. Their water was gone. The closest town was 25 miles away, and Dayton was silently planning to walk there the next day. Just then, a truck appeared.

The truck's driver helped push them out of the ash, and they drove back to Salta. Dayton decided to start out again. This time, he rented a four-wheel-drive pickup truck. He also met a group of German geologists who had been excavating in the altiplano. They gave him a detailed map, and told him how to get to Salar de Antofalla. An environmental filmmaker named Christian Gonzalez Bulo, who had worked with the team before, and his wife, Sandra, accompanied Dayton.

This time, the researchers did not get stuck. They drove without incident until they came to a hillside from which they could see Salar de Antofalla. "It was an absolute white moonscape," says Dayton. There was nothing there but rocks, ash, and the occasional sagebrush. The last transmitter signal pegged their falcon 25 miles to the north. So the group drove down the hillside and started across the salar. After they had gone a few miles, says Dayton, "All of a sudden, we saw a patch of green. It was an amazing emerald color. It just screamed at you."

The green patch turned out to be a vega, or oasis, chockful of marshgrass, flamingoes, flycatchers, and sandpipers. "They were all there because of this little 10-acre patch of grass. There was no question--if there was a peregrine around, this was the place."

The group made camp next to a huge mud mound that was the shell of a blown-out volcano, about two miles from the vega. While they were setting up, says Dayton, "Christian came over to me and said, ÔSandra thinks there is a peregrine sitting on the other side of that mound.'" Slowly, they crept around the mound. "That's your bird."

It was not their bird, exactly. It was not wearing the transmitter. But one peregrine foretold another. The next day, Dayton walked over to the vega and set up a lure. Just as he had finished, he looked up, and saw a peregrine sailing directly overhead. The sun glinted off a gold box on her back.

Dayton finishes his story just as we reach the flat muddy plains in the interior of Assateague called the Wash Flats. The late afternoon sun is melting into the horizon.

"We've got only about 20 minutes of daylight left," says Seegar. As he says this, a passage tiercel flies into view. Seegar throws out a lure, and soon has a falcon in hand. The catch brings the day's tally to a perfect 10. Though Yates's score will turn out to be 12, the double-digit figure seems a fitting close to this Zen-like day.

After Seegar bands the tiercel and paints its breast, he holds onto it for a moment. "Look at this bird. This is a beautiful bird," he says, predictably. "He's a survivor."

Swinging his arm in the now-familiar arc, he releases the young falcon. It takes flight just as the sky incandesces orange. The whoosh, whoosh of its wings underscores the silence of the hour.

Melissa Hendricks is the magazine's senior science writer.