A male Swallow-tailed Kite delivers a meal to its hungry offspring atop a loblolly pine in Williston, Florida. Adults primarily eat insects, but they capture frogs, like the one in this father's beak, as well as lizards, snakes, and nestling birds for their young. The chicks, now 20 days old, will fledge in about two weeks. Photo: Mac Stone

Science

The Secret Lives of Swallow-tailed Kites

Satellite tags are helping us better understand the nesting behaviors and migrations of these agile raptors, which hunt, drink, and bathe on the wing.

It’s a trap day, and biologist Gina Kent greets this one like she does any other, with an energy and brightness that’s hard to match at this early hour. Still, having been skunked four times in a row, her optimism is tempered with a bit more caution than usual. It’s late May, and she knows there won’t be many more chances to catch and tag a bird this breeding season. And with the sun now skimming the tops of the pines here in northern Florida’s Lower Suwannee National Wildlife Refuge, the team is burning daylight.

Kent and the others work quickly, assembling a camouflaged blind and aluminum poles, then stretching a billboard-size, gossamer net across a road overgrown with sawgrass. They’re careful to whisper and avoid eye contact with the occupants of a nest near the top of a nearby slash pine. With the set-up nearly complete, Kent returns to the vehicles parked just out of sight to retrieve the lure: a rehabilitated but non-releasable Great Horned Owl nicknamed Einstein. Walking back to the net with Einstein and his handler, Nan Soistman, Kent uses her body to shield the raptor from view; she doesn’t want any onlookers to associate the owl with the team’s activities this morning.

A Great Horned Owl receives a spray from a water bottle to cool it down in between trapping sessions (top); the rescue bird helps attract Swallow-tailed Kites to a mist net for GPS tagging. ACRI biologists Gina Kent and Ken Meyer wait in a blind, watching for the distinctive silhouette of a kite. Photos: Mac Stone

Having situated Einstein on his perch at the base of the net, they return to the blind and join two other team members, volunteer Grace Campbell and Kent’s longtime mentor and boss, Ken Meyer. Between the two of them, Meyer and Kent have been doing this kind of work for more than 50 years, so they know they might have a long wait ahead of them with little more to do than swat deer flies. Or all hell could break loose in an instant. With that in mind, Kent takes her seat on a small camp stool and settles in the only way she seems to know how—back straight, ears alert, eyes constantly scanning through the sliver-thin window. She’s looking for any sign of a Swallow-tailed Kite, a sleek, black-and-white raptor with a deeply forked tail known for both the effortless grace with which it soars and the precision with which it maneuvers when snatching prey or confronting threats on the fly. These birds will persistently, if not aggressively, defend their nests against Great Horned Owls, their most fearsome predators. It’s only a matter of time before one shows up; the question is whether it’ll swoop close enough to be caught in the net.

Ten minutes in, a kite is circling overhead, delivering an alarm call that sounds like a squeaky toy in the clutches of a hyperactive dog. As the kite falls silent, Kent looks away for a moment to adjust her stool. When she looks back toward the net, it’s there—more a clump of black and white feathers than a bird. Kent tears open the door of the blind and sprints to the kite suspended in the nylon mesh a few feet above Einstein’s head. Meyer arrives a moment later, and the two begin to untangle the puzzled bird.

Despite the fact that they’ve done this many times before, Kent and Meyer have never stopped marveling at the Swallow-tailed Kite’s beauty and elegance—the brilliant white breast and head capped by the iridescent blue-black of the back and tail; the hauntingly dark eyes; the impossibly long, slender wings. Still, the beauty of a kite in hand is nothing compared to that of a kite in flight, and the team is anxious to reunite this one with its mate and two others now worriedly circling and calling overhead. 

They weigh and measure the bird, band it, take feather samples for genetic testing. Finally, they loop nylon straps around the bird’s shoulders and affix a transmitter that looks like a streamlined, solar-powered backpack. If all goes according to plan, this device will provide the kite’s whereabouts many times a day for years to come. The information is critical to fill gaping holes in our knowledge about a vulnerable species whose range in the United States contracted from 21 states to 7 in the space of just four decades—and hasn’t recovered since. Along with the data from 15 other tagged birds, it will, the scientists hope, reveal subtle shifts in population trends, habitats that are key to the species’ survival here and in its South American wintering grounds, and some of the many threats it faces, both at home and along its arduous annual migration.

Before attaching a transmitter to the kite, they weigh and measure the bird (top). Gina Kent adjusts the harness of a solar-powered GSM/GPS transmitter (bottom), which can relay the bird's location for years. Photos: Mac Stone

With its data sheet completed and its transmitter turned on, the kite, now named Suwannee after the location of its tagging, is ready to go. The entire process, from capture to release, took little more than 30 minutes, but for Kent, it was long enough to form a bond. “Every one is special,” she says of the 210 birds she’s tagged. “I have relationships with all of them, because I've put my hands on them and looked them in the face, you know? I feel very responsible. I just want to make sure they do okay." 

The best way to do that is to send Suwannee back on his way, but this time carrying a payload that may help to ensure the well-being of Swallow-tailed Kites for generations to come.

Several days before the successful tagging of Suwannee, I visited Meyer and Kent at the suburban Gainesville headquarters of the Avian Research and Conservation Institute, an organization Meyer founded in 1997, just a year after he fitted his first kite with a satellite transmitter. Over coffee and leftover Easter candy, we pore over maps etched with colorful, squiggly lines representing the movements of tagged birds, and the two scientists do their best to encapsulate more than 30 years of research.

Click or move the slider, or use arrow keys, to follow Suwannee's journey; location is approximate for kites' safety. Credit: Tagging and tracking by the Avian Research and Conservation Institute, funded in part by Audubon and Friends of the Lower Suwannee National WIldlife Refuge.

When Meyer first began studying kites as a post-doc at the University of Florida in 1988, little was known about the species. This was particularly surprising to the young biologist given how visible the birds are during the breeding season, especially over their current stronghold of Florida. They’re regularly seen carrying cypress twigs and long strands of Spanish moss back to their nests, or carving beautiful, looping arcs through the sky as they forage over agricultural fields, picking off insects that might otherwise damage crops. Still, at the time, no one knew how many Swallow-tailed Kites existed, whether their populations were rising or falling, which habitats were critical to their survival, or where the birds went when they disappeared for the winter.

Meyer saw the lack of knowledge as a research opportunity—and a desperate need. “Here’s this amazing bird that captivates everybody’s attention,” he recalls thinking. “They’re thought to be a long-distance migrant, but nobody knows where they go or how they get there.” What’s more, scientists suspected the kite population might be critically low, and falling. “The only number that had been bounced around was 5,000 individuals,” Meyer says, referring to the population of kites that breed in the United States and is genetically distinct from kite populations that reside full-time in South America. “And we didn’t know enough to really do any good for them.”

Since then, Meyer and Kent, who joined ARCI in 2000, as well as raptor biologist Jennifer Coulson, who studies Swallow-tailed Kites in Louisiana, Mississippi, and Texas, have slowly been filling in the many knowledge gaps. They observed, for instance, that kites, unlike most other raptors, are highly social, forming so-called “neighborhoods” of half a dozen or so nests that the residents collectively defend from predators and reliably return to year after year. They discovered that the birds rely on a diverse mosaic of habitat types to meet their foraging and nesting needs. And with satellite transmitters, they finally discovered in 1996 where the kites go when they leave the United States in late summer: A 5,000-mile odyssey takes the birds across the Gulf of Mexico, down Central America, over the Andes, and across the Amazon Basin to ranchland in southern Brazil that bears a striking resemblance to north-central Florida.

While the research has answered many critical questions about the species’ basic natural history and breeding ecology, it hasn’t alleviated the scientists’ concerns. Although Swallow-tailed Kites seem to be doing relatively well in the far southeast corner of the country, they still haven’t recovered much, if any, of the range they occupied before their precipitous decline in the early 1900s. Permanent habitat loss due to timber harvest and agriculture has almost certainly played a role. But the researchers say there are also other factors limiting kites. One is the increase in predators like Great Horned Owls and Red-tailed Hawks that, according to Coulson, has been correlated with the ongoing sprawl of suburbs around cities in the Southeast. The birds’ social nature also makes range expansion inherently slower and more challenging. “They really want to nest close to other kites,” Coulson says. “So it’s unusual that you would have a neighborhood, say, 50 miles away from the nearest neighborhood. It might be five miles or ten miles away. And so for them to get all the way up to Minnesota, they’re going to need a stepping stone.”

Despite these limiting factors, the researchers have found that the overall population of kites that breed in the United States is larger than once thought. Meyer now puts the figure at somewhere between 15,000 and 25,000 individuals. And, promisingly, that number appears to have increased somewhat over the past decade. One reason for this modest uptick is surprising in light of the logging that precipitated the species’ initial decline. In the late 90s, Meyer and Kent began finding Swallow-tailed Kites nesting on timber company pine plantations. The more they looked, the more they found on those managed lands—and both thought there might be an opportunity to improve on what already seemed to be working in the kites’ favor.

Late one hazy afternoon, Meyer, Kent, and I drive southeast of Gainesville to visit what, in northern Florida at least, has become a fairly typical Swallow-tailed Kite nest. We’re headed to a pine plantation owned by Weyerhaeuser, one of the largest timber companies in the world, which holds more than 12 million acres of forested land in the United States alone.

When we turn off County Road 325 onto a dusty access road that cuts deep into the plantation, the contrast between habitat types on our right and left is striking. On one side stands a cluster of 100-foot-tall slash pines, home to a neighborhood of three kite families, each with a nest built into the uppermost branches of the tallest trees. On the other side of the road is a clearcut. Logged two years earlier, it’s showing signs of rebirth. Grasses and forbs now cover the insults that heavy equipment left in the earth. And across the entire expanse of some 85 acres, four-foot-tall pines shoot up at regular intervals where they were planted immediately after harvest. Despite the new growth, it’s a stark view from where we are—and presumably from the vantage of the kite nests next door.

Kites nest on commercial timberland in Levy County. Photo: Mac Stone

Meyer and Kent don’t seem the least bit concerned. More than half of all known Swallow-tailed Kite nests in the United States are in tracts much like this one. That’s not particularly surprising given that the vast majority of timberlands in the Southeast are privately owned working forests. Although these tracts are by no means pristine, commercial forests still provide critical habitat. “Yeah, it might look ugly,” Meyer says, “but you know what, it mimics the natural habitat. When you think about the disturbance factors in Florida, it’s fire and storms. Timber harvest mimics those disturbances.” When conducted sustainably, he adds, it creates a mosaic: a heterogeneous patchwork of stands of varying ages and heights that provide kites with nesting, roosting, and foraging habitat, all within relatively close proximity of one another.

Meyer’s appreciation for commercial timberlands—what he calls “surrogate wildlife habitat”—didn’t grow overnight. It began in the late 90s with he and Kent seeking permission from timber companies to survey for kite nests on their land. Several commercial foresters obliged, and one, Steve Lowrimore, took particularly keen interest in the research. Before long, Lowrimore, who worked at the time for a division of Georgia Pacific before it was eventually sold to Weyerhaeuser, was tromping into the woods with Kent to look for nests on tracts that were scheduled to be cut. On a number of occasions, he delayed a timber sale or asked loggers to leave a buffer around active nests, at least until the chicks had fledged.

Swallow-tailed Kites 80 feet up in a Loblolly Pine in Withlacoochie State Forest, Florida. Video: Mac Stone

Increasingly, the broader scientific and conservation community was also acknowledging that highly managed commercial timberlands can provide critical habitat for many wildlife species. Organizations like the American Bird Conservancy, the National Audubon Society, and the Sustainable Forestry Initiative began working with timber companies to develop a certification program for commercial forests that are managed to protect water and air quality and support biodiversity. Frequently Meyer and Lowrimore were called in to assist with management guidelines and training for foresters and loggers.

The motivation for conservation groups to participate in these collaborations is simple, says Emily Jo Williams of the American Bird Conservancy: “Having economically and ecologically sustainable forests is much better than losing those forests altogether.” In addition, she says, while many bird species require relatively pristine habitats like those found in national parks, wildlife refuges, and other conservation lands, not all benefit from them. For example, Prairie Warblers do quite well in recent clearcuts like the one I visited near Gainesville. And when those young pines get a little taller and denser, Swainson’s Warblers typically move in.

Over the years, Meyer, in collaboration with Lowrimore and other foresters, has come to three main conclusions about what makes commercial timberlands good for Swallow-tailed Kites—and what would make them better. Thinning is key. And fortunately for the birds, it’s standard practice in commercial forestry. When a stand is between 10 and 15 years old, Lowrimore says, timber companies systematically remove one out of every three to five rows of trees, as well as any stunted or malformed individuals. The remaining trees undergo a tremendous growth spurt in response to reduced competition, and kites frequently select the tallest of those emergent trees, as they provide easy-access nest locations for the long-winged birds.

Additionally, in contrast to what’s becoming increasingly common on conservation lands, commercial foresters rarely use fire as a management tool, largely because it’s risky and expensive to manage a burn. As a result, the understory of commercial forests tends to be much thicker, a factor that discourages an expanding population of Great Horned Owls from settling in. 

Finally, Meyer has concluded that longer rotations—the frequency with which stands are harvested—are better for kites. Older, taller trees, as well as nest trees that remain standing for a number of years when kites return to the same stands to breed each spring, improve breeding success. Unfortunately, Meyer and Lowrimore acknowledge that rotation is driven by market trends for various timber products and the availability of mills to produce those products, two factors they have no control over. The closure of a plywood mill in central Florida several years ago, for example, shifted the emphasis away from larger trees toward smaller ones harvested for utility poles and pulp, says Lowrimore. “You go from needing a minimum of a 13-inch [diameter] tree to make that plywood spec, which necessarily means a longer rotation. Then, suddenly, there's not much of a market for that anymore.”

While Meyer acknowledges that kites can make do in younger forests, particularly if some larger trees are left standing to serve as nest habitat, he would love to see markets shift back in the other direction. “If you wanted to support Swallow-tailed Kites, the best thing you could buy would be a bunch of plywood. Make everything out of plywood.”

Right after liftoff from a tiny airstrip near Gainesville, the pilot banks the single-engine Cessna and heads south. With the morning sun still low over the horizon, Kent, in the front passenger seat, looks expectantly toward a part of Florida few people ever see, a stretch of relatively remote riverine habitat where swamps morph into dark channels lined with towering old-growth cypress trees draped in curtains of Spanish moss. This is where Swallow-tailed Kites gather by the thousands to forage and roost before setting off on their impossibly long journey south. This is also where Kent and Meyer can most efficiently assess trends in the species’ population.

As the plane approaches an old-growth stand that Kent has flown over dozens of times in the past, and will likely pass over several more times before summer’s end, the bright white heads of dozens, then hundreds of kites begin to come into focus. Soon, there are far too many birds to count on the fly, and so, as the plane flies a systematic course over the roost, Kent snaps overlapping photographs for later analysis.

Each year between early July and September, the vast majority of Swallow-tailed Kites that breed in the United States funnel through this and about a dozen other pre-migration roost sites dotted along Florida’s interior. These ever-shifting assemblages of hundreds to several thousand kites vary in number as birds arrive and then depart for distant shores. For a species whose nests can be difficult to find, the roosts provide a rare opportunity for the scientists to assess trends in the number of kites breeding in the United States in a given year. And for the birds themselves, the abundance of insects over the swamps, rivers, and agricultural fields of Peninsular Florida provides the rich energy source needed to get them started on a successful migration.

The first leg of that journey is often the most harrowing—and deadly. As each bird departs the United States, it faces a daunting passage over the Gulf of Mexico. While some kites stop briefly in Cuba on their way south, the majority make a non-stop, 500-plus-mile flight directly to Mexico’s Yucatán Peninsula. For a bird that rarely flaps its wings, a tailwind is essential, especially during this stage of the journey; kites can only survive for about four days over open water, and will typically wait at a roost for favorable winds before they set out. Unfortunately for some, those conditions can change mid-flight, forcing birds to tack off course, turn back, or be lost at sea.

Kent and Meyer have spent many an agonizing day watching as tagged birds flew unwittingly into tropical storms or unrelenting headwinds. A bird nicknamed OK, for instance, was one of this summer’s earliest southbound departures, but had the misfortune of flying into Hurricane Barry shortly after leaving the Florida Coast and being blown off course to Louisiana; she crossed the Gulf successfully more than a week later. “We’re watching it, and we know what the wind’s going to be like tomorrow—and the bird doesn’t know,” Meyer. says “If you were a poet, you could spend your life writing about the migration of Swallow-tailed Kites. There’s all these existential dramas going on.”

Meyer counts roosting swallow-tailed kites from the air over south Florida. Photo: Mac Stone

The dramas don’t stop when the kites reach land. There, countless other obstacles still lie in their path, from predators and poachers to unpredictable storms over the Andes. “Each night, they’re going to a new place, and they don’t know where the predators are. They don’t know what the new risks are,” Kent says. She and Meyer can only watch from a distance as the tagged birds’ transmitters relay their GPS coordinates via cell towers along the way, hoping the birds or the transmitters won’t wink out. 

When they arrive in Brazil’s state of Mato Grosso do Sul, nearly three months after leaving Florida, they pass over family-owned cattle ranches, pastureland interspersed with stands of tall trees. Increasingly, however, these landscapes are being converted into industrial-sized monoculture plantations of soy beans and sugar cane. In addition to the loss of the mosaic of habitats kites depend on, pesticide use on these massive farms can both reduce insect abundance and poison kites. The scientists suspect that kites accumulate toxins when they consume insects that have been sprayed. “We’re losing these birds in South America when essentially they should just be on vacation,” Kent says. “They don’t have to raise chicks. They don’t have to defend a territory. They just have to take care of themselves. So when we see them go down near agricultural fields where herbicides and pesticides are used, it’s suspicious.”

In many ways, knowing about threats like these only gives Meyer and Kent more to worry about. But knowledge of where individual birds go and what they face along the way may provide insights into future population shifts. And if, for example, they were to document an increase in the mortality rate of overwintering birds, the information could prove useful in advocating for stricter international environmental protections for kites and their habitats.

In just a few short months, they’ll have a wealth of new data to help them in this task. Of the 16 tagged kites, 11 have already departed for South America, and the others are not far behind them.

Suwannee, who successfully fledged a buff-headed chick after he was tagged, has spent the past six weeks recuperating and preparing for the long migration ahead. Rather than joining larger groups of kites at roosts further south, he spent most of that time closer to home, foraging in pastureland to the east of his nesting territory and roosting nearby with several dozen kites along the Suwannee River. Finally, on a bright, clear morning early this month, he took to the air and left the Florida coast. Exactly what his future holds is impossible to predict, but Kent and Meyer will be watching every step of the way.

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This story was published in partnership with bioGraphic.

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