Giant lizards, hissing ducks, and pythons: Florida has an invasive species problem - National Geographic

THE EVERGLADES, FLORIDAGillian Hicks and her boyfriend, Michael Litersky, were sitting on the porch of Hicks's apartment in Lake Worth Beach, Florida, when they noticed a strange animal slinking along the fence. It looked a bit like a raccoon, but its color was too mustardy, and a bit like a cat, but its tail flexed and gripped with remarkable dexterity.

A Google search suggested the mysterious beast might be some type of primate, maybe a lemur. Whatever it was, it was cute—with the big, imploring eyes and rounded ears of a teddy bear—and seemed friendly. The internet says lemurs eat fruit, so Litersky set out some watermelon. As the sun dipped into the Gulf of Mexico on that muggy summer evening in 2019, the couple watched the maybe-a-lemur grasp the melon chunks in its clawed forepaws and nibble away at them.

The next morning, Hicks awoke to screams. Sprinting out of bed, she discovered Litersky and the little animal doing battle in the kitchen. As Hicks would later explain to a local newspaper, Litersky had gotten up early to go to work. When he'd opened the front door, he'd been surprised to find the critter was still there, waiting on the step. And then, Hicks recounted, "it just bum-rushed him."

Litersky tried to shoo his assailant outside, but it latched onto his leg, biting him and slashing his calf. Grabbing a frying pan, Litersky backhanded the animal into the bathroom while Hicks dialed 911. Sheriff's deputies arrived quickly, but, outmatched, they could only peek around the door and watch as the quadruped ripped up the shower curtain. Finally, a team of animal control officers and officials from the state wildlife agency managed to corner the creature. It wasn't a lemur but a kinkajou, a carnivorous mammal native to the South American rainforest. Hicks drove Litersky, bleeding, to an urgent care center for bandages and antibiotics. His adorable assailant was taken to a state facility and later adopted out to a Floridian with a penchant for (and proper experience with) exotic pets.

Accounts of such odd creatures running amok in Florida have become commonplace—in an indignant editorial in 2019, the Orlando Sentinel dubbed the Sunshine State a "Jurassic Park" of exotic species.

That spring, for example, in Palm Beach Gardens, thousands of poisonous cane toads—introduced to Florida years ago from South American to control agricultural pests on sugarcane plantations—emerged from the city's gutters and canals, taking over an entire neighborhood. A few months later, in Melbourne, a 200-pound feral hog, a descendant of pigs brought to the peninsula by Spanish conquistador Hernando de Soto, chased two girls at a bus stop before mauling a man attempting to catch it. And not long after, scientists announced that hundreds of rhesus monkeys living in a public park in Silver Springs, kin to a colony of monkeys imported in the 1930s for a jungle boat attraction, had begun spreading across the state. The monkeys are known to fling their poop at gawking humans—feces, scientists warned, that contain a communicable form of herpes.

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Left: Wild hyacinth macaws are rare in their native Brazil, Bolivia, and Paraguay, but aviaries in Florida breed and sell them as pets for top dollar.

Right: This bearded dragon was surrendered on an Exotic Pet Amnesty Day in Florida, when the state accepts any exotic animal without question. Its aim is to prevent owners from releasing unwanted pets into the wild.

Such interspecies assaults are often written off as a logical product of Florida's ambient weirdness. They're better understood, however, not as random attacks but as skirmishes in a war the state has been waging for decades.

According to the U.S. Fish and Wildlife Service, Florida is home to more nonnative plants and animals than any other part of the country. This set of intruders now includes hissing ducks, walking catfish, hermaphroditic river eels, bloodsucking worms, pet-eating monitor lizards, dog-size rodents, gigantic snakes, and rodent-size African land snails, which, according to rumor, are smuggled in for esoteric religious rituals.

The origins of this absurd but somehow perfectly Floridian situation are sundry. The state's subtropical climate, its many seaports and airports, bountiful farms, and intractably oddball culture—heavy on theme parks and the kind of Tiger-King-style eccentrics who have a yen for weird pets—combine to produce a welcome habitat for fugitive species. (Young collectors are helping fuel a boom in exotic pets in China.)

A colony of vervet monkeys lives near Fort Lauderdale-Hollywood International Airport. They're believed to be descendants from a breeding center that supplied primates for biomedical research in the 1940s.

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While most foreign plants and animals promptly die off or tuck themselves into a harmless ecological niche, some blossom uncontrollably, dominating native species and despoiling local ecosystems. The words biologists have long used to describe the influx of foreign organisms—"alien" species "invading" a "native" land—have spilled over into present-day human bigotry. A 2020 New York Times piece notes that members of the far right have taken to referring to immigrants and racial minorities as "invasive species."

Today, Florida's multitudes of introduced species are an especially dramatic expression of global and national disasters. Every year, invasive species cause an estimated $1.4 trillion in various forms of damage and control costs worldwide, according to one widely cited estimate. In the United States, nonnative weeds alone annually cost $34 billion to remediate, and the Norway rat—thought to have first arrived around 1775 in the company of Hessian mercenaries hired by the British to fight the rebelling American colonists—is estimated to destroy $20 billion worth of stored grain.

The danger of transporting an organism to a strange land lies in its potential to disturb an established habitat, one with a brittle equilibrium, carefully composed over millennia, of predator and prey and symbiotic balance. Although most exotics loosed into a new world don't survive, a few find themselves at a competitive advantage to the local plants and animals. These species become classified as invasive only when their existence is discovered to be a problem—when, say, in the absence of their former enemies or the presence of new, inferior peers, they become supremely powerful, tyrannizing the food chain and throwing the whole delicate balance into riot.

In 1999, ecologists Daniel Simberloff and Betsy Von Holle proposed the unsettling theory of "invasional meltdown," in which the introduction of a single nonnative species clears the way for more nonnative species, leading to full-on ecological collapse. The addition, for example, of grazing cattle to rangeland in the American West allowed European cheatgrass to supplant native grasses. The flammable cheatgrass, in turn, dramatically increased the rate at which the plains suffered catastrophic fires, obliterating other native shrubs and vegetation.

Now, with climate change, scientists expect the problem of invasive species—already estimated to cost the U.S. more than $120 billion dollars annually—will only deepen nationwide. The hostilities in Florida may be but a preview of a coming national onslaught of bothersome or dangerous unwelcome arrivals. Think murder hornets.

An Argentine black-and-white tegu occupies Rodney Irwin's couch. Known as the Tegu Man, Irwin captures and sells the invasive lizards, which will eat almost anything, including the eggs of endangered sea turtles.

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Left: Walking catfish, native to Asia, walk themselves to aquaculture facilities where they feast on millions of dollars' worth of farmed fish.

Right: Many Floridians have a peculiar hatred for Muscovy ducks, which are native to Central and South America. This one lives at Duck Haven, in Margate, Florida, the only rescue facility in the state exclusively dedicated to the species.

Florida goes to war

The Florida Fish and Wildlife Conservation Commission (FWC) is the beleaguered agency tasked with coordinating the war on invasives. The Everglades is where FWC deploys much of its staff and materiel, in the form of trucks, boats, and wildlife biologists, and the battleground for which the stakes of victory are highest. Its 2,400 square miles of sawgrass marshes, wet prairie, freshwater ponds, cypress swamps, and forested uplands provide drinking water to one in three Floridians and irrigation for every farm south of Fort Myers.

Flat as a putting green, the Everglades wetlands can soak up billions of gallons of rain and storm surge, preventing flooding during seasonal hurricanes. Setting aside any abstract appreciation for its natural magnificence, without the Everglades, and the hundreds of plant and animal species that keep it a viable ecosystem, South Florida's eight million inhabitants would have to find somewhere else to live.

But signs abound suggesting that the war is already lost. The number of leviathan Burmese pythons despoiling the Everglades by gobbling up native species has grown an estimated 20-fold since 2005. Reef-annihilating lionfish have overrun the state's coastlines and breeched the waters of Louisiana and Georgia. Florida's hog population now exceeds half a million, a tusked legion marauding citrus orchards and golf courses.

FWC's strategy centers on preventing exotics from getting loose, mostly by inspecting and intercepting cargo. Occasionally, the agency also steps in to resolve what it euphemistically terms "conflict wildlife situations"—instances when humans and exotic fauna meet perilously. The agency recently banned pet owners from possessing any of 16 species of non-native reptiles, including green iguanas and Nile monitor lizards, deemed to be at particularly high risk of slipping back into nature. If invasives do escape and enter the wild, wildlife officers hunt and exterminate some, and FWC uses various incentives in the hope that Floridians themselves will eliminate the majority.

FWC pays a bounty for dead Burmese pythons: Accredited hunters receive $50 for pythons measuring up to four feet, plus $25 for each additional foot of serpent, with a special bonus if the catch is a pregnant female. It exempts feral hogs from its standard hunting rules, allowing them to be pursued and shot on public land year-round with no license, no size restrictions, and no bag limit. The agency even promotes a cookbook devoted entirely to recipes for lionfish—a species from the Indo-Pacific whose aggressive consumption of local species has thrown coral reef ecosystems out of whack—hoping that increased demand will spur entrepreneurial fishermen to action. (One way to fight invasive species? Eat them.)

For every victory—a combination of herbicides and controlled burns have halted the decades-long spread of river-choking melaleuca plants, for example—there are new fights with fresh enemies. Here comes the Brazilian pepper tree, the Mexican bromeliad weevil, and the capybara, a giant aquatic rodent from South America. "We're all playing Dutch boy with the dike," said Frank Mazzotti, a University of Florida biologist, after a glum summit on the conflict's progress in 2019.

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Left: Salmon-crested cockatoos, native to southeastern Indonesia, are known as affectionate—but very loud and demanding—pets.

Right: This feral piglet was picked up in the woods after its mother was killed. Feral hogs, now widespread across the southern U.S., destroy crops and sensitive ecosystems with their rooting.

A peculiar hatred

In Florida, even comparatively benign creatures can become objects of violence, as evidenced by the peculiar hatred of Muscovy ducks, accused by municipalities of seizing food and habitat from more decorous native birds. 

The Muscovy, it's true, is an odd duck. They're possessed of patchy coloring, clumsy proportions, and eyes ringed by a wet-looking inflammation of red caruncles that bring to mind a neglected tumor. They're also inept flyers, prodigious defecators, and notorious belligerents known to accost pedestrians and block traffic. And they don't quack: They hiss. Even their name confuses: The ducks hail from Brazil, yet, for reasons no one can remember, they were christened after an antiquated term for the region surrounding Moscow.

This bird's behavior and lack of surface charm have made it a magnet for put-downs. The president of a Jupiter homeowner's association denounced Muscovies to the Palm Beach Post as "messy." A spokesman for the Miami Zoo once called them "feathered rats." Even the Audubon Society refers to Muscovies, in an official publication, as "dumpy."

History teaches us that such casual animus reliably incites bloodshed. Indeed, in Florida, Muscovies are routinely kicked, clubbed, strangled, stabbed, decapitated, shot with pellet guns, and pummeled with golf clubs. A brood of ducklings was once run over with a lawnmower. Condo owners organize killings in which entire duck families are butchered or forcibly expelled from their properties' water features. It is, in fact, legal to kill a Muscovy duck in Florida, though, per state law, their end must be "humane."

Floridian contempt for the duck is hardly universal. Long ago in Mexico, the Aztecs believed Muscovies to be the alter ego of the mighty Wind God, Ehecatl, and rulers adorned themselves in rich cloaks sewn from their feathers. Archaeologists have uncovered surpassingly beautiful images of the bird, shaped in clay and chiseled in basalt.

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Sharing the Mesoamerican empire's reverence is Eunice Sivertsen, an 83-year-old resident of Margate, Florida, the ducks' present-day champion and savior. In the war on invasives, Sivertsen is an outstanding pacifist. For more than 40 years, she's run Duck Haven, a nonprofit sanctuary devoted to Muscovies, out of her back patio, transforming a '60s-era ranch house into an anatine Lourdes. Because they're not indigenous to Florida, no wildlife shelter in the state will take them in. Only her.

On a mellow February morning, I visited Sivertsen, a short, snappy woman who, after a half-century in Broward County, still retains the adenoidal timbre of her native Queens. Sivertsen explained that she used to nurse injured Muskovies back to health and then let them go. But after FWC labeled them invasive, in 2010, making it illegal to release them into the wild, she now discharges her rehabilitated wards to a secret network of private estates whose owners share her fondness for the befuddling ducks.

Sivertsen herself houses about 60 long-term residents who suffer from permanent disabilities. She gave me a tour of her facility, a packed warren of chicken wire, dog houses, Astroturf, and plastic Jesus figurines, and introduced me to her waddling convalescents.

"That's Dixie," Sivertsen said. "Cookie. Ariel. Caroline. Paul. Santeria. Bobby and Peter. Sometimes Bobby and Peter fight." She narrowed her eyes. "But not when I'm around."

In Sivertsen's description, Duck Haven is little different from any of Florida's other assisted-living centers, thick with drama and bruited gossip. Cricket has a rude habit of bothering Nancy, who's old and unwell. Cookie, a flirt from Louisiana, is always chasing after Ollie. Paul and Judy are a couple, but they occasionally stray. Pixie is letting herself go. Sivertsen denied having a favorite duck, other than Charlie—"my sheriff"—who had been with her 11 years. (Charlie would die during the COVID pandemic. In his stead, Sivertsen soon deputized a Charlie II.)

The bulk of her day is devoted to setting out the Muscovies' meals (mostly scratch grains, lettuce, and dog chow) and cleaning duck feces. She's helped by a few volunteers fulfilling court-ordered community service, as well as her young grandchildren, who live next door. Because her shelter caters to an invasive species, it's ineligible for state funding. Duck Haven costs over $3,000 per month to manage. Much of Sivertsen's Social Security check goes to food and electricity, both to keep the ducks warm in winter and their pond water running all the time, with the rest made up by donations.

She pointed out a special paddock for a quartet of blind Muscovies and another for ducks mangled by "angel wing," a syndrome caused by a bread-heavy diet, in which the last joint of the forelimb becomes twisted, rendering the duck flightless. Two ducks were missing lower beaks, an injury likely caused by animal attacks, leaving their tongues lolling. Sivertsen bought one of the beak-less birds a prosthetic, made of plexiglass, for $2,500. It lasted a few months, but on July 4, a neighbor set off some fireworks and the startled duck ran headlong into a wall, shattering it.

"I hear what people say, but I don't think they're ugly," Sivertsen said, picking up Charlie and cradling him. The wart-faced duck, alarmingly large but calm, flopped limply into Sivertsen's thin arms. "I love 'em."

A homeowner caught this Burmese python after it attacked his chickens. There are likely tens of thousands of the snakes in the Everglades, where they're decimating native wildlife, including bobcats, deer, and foxes.

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Into the Everglades with Captain Hank

I asked a windblown man in his mid-50s named Captain Hank to take me into the Everglades on an airboat. Hank Ridings is a plastering contractor who has a sideline as a tour guide and amateur naturalist. He grew up next to the Everglades and ever since he was kid, has been coming out to the swamp to hunt, fish, and, occasionally, pound beer.

With Captain Hank's guidance, I was hoping to spot a Burmese python. Python bivatticus has become the reigning symbol of Florida's invasive species problem and of ultimately futile attempts to manage it. During the '80s and '90s, when the exotic pet industry boomed, people bought pythons as babies but turfed them out into nature when they grew and grew and grew into ten footers—and more. How many pythons now haunt the Everglades is anyone's guess, but, according to the Miami Herald, estimates go as high as 300,000.

Pythons have no natural enemies and are wily predators, spending most of the day camouflaged underwater and hunting at night when they ambush and enfold their prey, suffocating them by compressing their chest cavities. Their effect on the Everglades has been cataclysmic. Burmese pythons are responsible for the effective disappearance from the region of opossums, foxes, marsh rabbits, bobcats, foxes, and raccoons. They feast on endangered water birds, such as roseate terns and Cape Sable seaside sparrows, turtles, even deer and alligators. In towns around the Everglades, flyers advertising lost dogs and cats have multiplied. The pythons, however, rarely attack humans.

FWC has tried increasingly desperate measures to cull the snakes—python-detecting dogs, infrared sensors, drones. One scientist outfitted captured pythons with radio-beacons and let them go, hoping his Judas snakes would head back to their lairs and betray the whereabouts of others. (They didn't.) In January 2020, Governor Ron DeSantis opened FWC's Python Bowl, a contest where the person who killed the most snakes in a 10-day period would receive a $5,000 ATV. The event, which attracted 750 people from 20 states, produced a mere 85 dead reptiles. (These dogs help sniff out invasive species.)

"There's never been a successful eradication of reptiles in history," Captain Hank observed, "so that's probably not going to happen here. They're integrated into the system, and they're not going anywhere."

Captain Hank wasn't entirely correct: Dozens of reptile species have, in fact, recently become extinct, including some done in by invasives. (The Jamaican giant galliwasp, for example, was killed off by mongooses that plantation owners introduced to combat rats.) And while invasive species are without question a serious environmental problem, I began to wonder whether their demonization and the state's campaign, like many xenophobic offensives, doesn't serve too as a handy diversion of blame.

The effects of invasive species on the Everglades pales in comparison to everything else we humans have visited on the region. It's an open question, says Joel Trexler, a professor of biological sciences at Florida International University, whether "the Everglades" even exists today, or whether it has become a kind of stage-managed facsimile. The taming of the swamp started in the 1800s when the state began draining it with thousands of miles of canals to make way for farms and people.

After a fatal flood in 1928, the U.S. Army Corps of Engineers built a system of levees, pump stations, dams, and locks. For more than 70 years, the Everglades have been dredged and diked, polluted by phosphorus and mercury run-off from sugarcane and tomato fields and by the millions of gallons of pesticides and herbicides sprayed in the campaign against exotic plants and animals. In a century, our imprint has winnowed the Everglades to half its original size.

More broadly, given the constant intermixing of the world's life forms, it's not always easy to determine whether an animal is foreign, let alone invasive. Dogs arrived in North America more than 10,000 years ago. Are they still exotic? Ill effects of most foreign plants and animals, moreover, are negligible—few Americans, for example, hate Queen Anne's Lace (a native, reportedly, of Afghanistan before later spreading to Mediterranean Europe). Some are even crucial. We would be in trouble without the pollinating services of honeybees, brought to the Virginia colonies by the English.

Meanwhile, some undeniably pernicious exotics avoid the label of "invasive." It's estimated that house cats—Felis catus, domesticated a thousand years ago in Mesopotamia—kill a billion birds or more every year worldwide. (The 232 animals in this photo were killed by house cats in just one year.)

It is ironic, too, that the word invasive is applied by the one species that is the most invasive of all, spreading unchecked across Earth, claiming dominion over every plant, animal, bacterium, fungus, and virus in its orbit—and struggling to correct imbalances of its own making. Florida's fixation on invasive species may soon be moot. In less than 30 years, scientists say, climate change may put much of the Everglades underwater.