Visiting the Heart of Alligator Country
Our writer learns firsthand what it takes to study the health of American alligators in their Everglades habitat
- Doug Stewart
- Jun 01, 2000
For the moment, Franklin Percival and his quarry, a six-foot-long American alligator, are at a standoff. Percival is standing in an airboat at midnight in an expanse of sawgrass deep inside Everglades National Park. As a U.S. Geological Survey wildlife ecologist based at the University of Florida, he is helping to survey the health of juvenile alligators in South Florida´s watery interior. I am tagging along to witness and report on the research firsthand. At the end of a long pole in Percival´s hand is a wire loop he has slipped past the young alligator´s snout and tightened round its fleshy neck. In the water, the gator is holding its toothy jaws open, waiting for a chance to chomp down on any of the scientist´s appendages.
But Percival has a simple trick up his sleeve. With another pole, Percival presses down on the top of the alligator´s hard scaly snout. The reptile´s jaws are built to bite down hard and not let go--an adult´s can exert more than 1,000 pounds per square inch--but the muscles keeping its mouth open are far weaker. The creature´s small legs and webbed feet are designed for propulsion and maneuvering, not for attack. Soon the animal submits to a brief capture.
The American alligator is the closest thing we have to a living dinosaur. While Tyrannosaurus and its ilk died out some 65 million years ago, Alligator mississippiensis has adapted and thrived in the modern world--even, for better or worse, in close proximity to Homo sapiens floridianus. Fortunately for the latter, modern alligators are far smaller than their largest ancestor, which stretched 36 feet from snout to tail. A 13-foot gator today is considered a whopper.
Alligators are found in freshwater lakes, rivers and marshes through the Southeast, as far west as Louisiana and Texas and as far north as the Carolinas. Florida, however, is Alligator Central, harboring more than one million of the reptiles--possibly as many as two million. Although the species´ numbers seem to be holding steady, it now faces challenges to its health and well-being in the heart of its range. In parts of South Florida and Central Florida, alligator populations are faced with habitat loss, pollution and declining water quality.
Alligators are the top predators in their wildlife community; their only natural enemies, after they grow to about four feet, are larger gators and humans. Their top-of-the-food-chain status makes them of special interest to ecologists, wildlife managers and policymakers. "The alligator is the ultimate monitor for water and its environment generally, especially over large areas," says Paul Cardeilhac, an aquatic-animal veterinarian at the University of Florida at Gainesville. Alligators can live for 30, 40 or 50 years--even in some impure environments--and their bodies accumulate a record of what they have ingested. "If the alligators on a lake are in trouble, you´d better take a look at that lake," says Cardeilhac.
The locale that particularly concerns scientists right now is the Everglades, focus of a proposed 20-year, $8 billion federal restoration effort. The "river of grass" has been clogged, drained and diverted by more than 50 years of earth-moving in the name of flood control. The restoration plan, now before Congress, would benefit wildlife by reviving some of the original freshwater flow. "Alligators are just one of the species here that people are looking at, along with panthers, fish, wading birds and others," explains U.S. Geological Survey ecologist Ken Rice, who has pulled together the on-going effort to check how alligators are faring at six spots in and near the Everglades.
The night I go on the field trip to snare gators, Rice is joined by ecologist Percival. With Rice´s agency airboat in tow, we ride out to the park on a road that runs along the crest of a giant levee. At intervals we pass pump stations that push water under the road from north to south. Much of the Everglades is now chopped up by such levees and dikes and squeezed at the edges by cane fields and fast-growing development.
"The water in every compartment here has been managed differently," says Rice. "We´re trying to look at that information and then look at differences in the alligators. Then you can start to ask: ´What would happen to the wildlife here if we got rid of this levee? What would happen if all these marshes were managed in this or that way?´ That can help the decision makers choose the best way to restore the Everglades."
Entering the park itself at Shark Slough, we follow a narrow asphalt road with thick stands of spikerush on either side. Great blue herons lumber into the air at our approach. A turtle and a bobcat crawl and dart, respectively, into the grass, and a tiny white-tailed deer with impressive antlers crosses the road before turning to examine us from shallow water. Up ahead, a two-foot alligator crawls off the pavement. Farther on, a seven-footer contemplates us from a hole beside the road. The team of Rice and Percival is one of five that each hopes to detain and assess at least 20 juvenile gators. Five captured alligators from each of the six sites in the study later will get full-fledged workups.
Out on the water, Rice plays a spotlight over the water from side to side. Telltale spots of amber glow here and there where alligator eyes watch us. Many prove to be hatchlings, and many more are well beyond the study´s six-foot size limit. But soon Percival is snaring one juvenile after another. Several repeatedly try to chomp down on the side of our aluminum airboat. As Percival hauls the study subjects aboard, Rice straddles them and holds their snouts shut with his hands. My job is to wrap their jaws with black electrical tape. Rice advises, "When you think you´ve got enough wraps, do it one more time."
I do. I´ve learned enough about the creatures to know that they often eat by tearing their food along a dotted line of their own creation. That is, for large prey, such as deer, a gator clamps down with its close-set, spikelike teeth to leave a long line of perforations. Then, flailing its head from side to side, the predator breaks loose portions small enough to swallow. However, for small prey--fish, rodents, snails, crabs, birds--a gator points its head up and swallows the meal whole, letting its gizzard do the chewing.
Under restraint and up close, the gators are beautiful to behold. The scales on their bellies are a lustrous ivory, their corrugated backs a dark gray-green. The insides of their mouths are almost white and strangely featureless in the glow of our headlamps: A flap of flesh covers their throats, an adaption that keeps water out, as their lipless jaws are not airtight. Once the animals are hog-tied, Rice and Percival draw blood and take a small protruding ridge, or scute, from the tail for later analysis.
Many of the animals we spot simply float watchfully. In marshes open to the public where boating and some controlled hunting are permitted, alligators are far more skittish. "One thing we know about alligators, they don´t like to be fooled with twice," says Percival. That probably explains why surveys in the 1960s and early 1970s seemed to find that Florida´s gator populations were rapidly dwindling. "Alligator hunters had been hammering them for so long, they´d gotten shy, so we thought the population was lower than it was," Percival explains. Alligator hunting was banned throughout the Southeast in the 1960s, though poaching was rampant throughout the decade. The reptiles landed on the federal Endangered Species List in 1973, and a clampdown on alligator products largely put an end to the poaching.
Today, there are doubts that the species was ever really in trouble. "Had we known then what we know now, alligators would never have been classified as endangered," Percival says. Gators were delisted in 1987, and controlled hunting now is permitted in Florida and elsewhere. Trade in gator meat and hides remains restricted, however, to discourage trafficking in crocodile parts. That´s because the two species can closely resemble each other, and crocodiles are indeed endangered in the United States. (Crocodiles live in salt water and brackish water, thanks to desalinating glands that alligators lack.)
Still, all is not well with alligators. In the five years of the study, gators in the Everglades have consistently been thinner and laid fewer eggs than members of the species in less-protected areas to the north. Rice, Percival and other gator experts suspect poor nutrition is to blame, not disease or contaminants. The Everglades are not nearly as rich in nutrients as are the lakes farther north, which receive more nutrients in runoff and also naturally contain more organic material. So the density of alligators here is lower; in all, there are perhaps tens of thousands of the animals in the park and its environs--a small fraction of Florida´s total.
During "dry-downs" in the spring, back in the days when the swamp´s shifting water levels were natural and not manipulated, Rice says, "About the only open water down here was in gator holes, which the animals dig in the muck. Prey would be concentrated there." As a result, when water was low, the gators feasted. In the last few years, however, dry-downs in the Everglades have been fewer and less pronounced than usual (though over the long run, many sections have become dryer than they once were). With storm-driven high water, prey has been dispersed, and the gators have had less to eat. Or so goes one theory. Another possibility, although remote, is that lake alligators up north eat so much they´re overweight--and that Everglades gators are actually healthier for being so svelte. The new survey may help settle the matter.
Long after midnight, Rice calls it a night and revs up the airboat´s 300-horsepower aircraft engine to show me a spot he knows--a secluded pool next to a small tree island, mostly hidden by sawgrass. A mama gator dug and maintains the pool, which is close to 12 feet deep. Just visible behind the tree trunks at the edge of the island is a mound of dead vegetation: an alligator nest. No one is home that we can see.
Alligators are not normally known as tender parents. A popular notion is that males, given a chance, eat their young. Larger alligators do eat smaller alligators--but some reports of cannibalism in the nest may be erroneous. As young start to emerge, the female tears open the nest, and she often moves hatchlings and unhatched eggs by picking them up in her mouth to help the process along. "She will sometimes help break open the shells by pressing them against the roof of her mouth with her tongue," says alligator biologist Kent Vliet of the University of Florida. "If there´s a bad egg, she swallows it instantly." (Try telling that to the jury.) Hatchlings, born in early summer, stay under mom´s protection, or at least in her vicinity, for several months. In some cases, Vliet says, mothers let one- and even two-year-olds hang around the gator hole, "presumably until they try to eat the next group of hatchlings."
Alligators become sexually mature once they reach about six feet in length, which can take more than 10 years. As for courtship, which Vliet in his younger days observed while submerged a few feet away, "It´s an amazingly gentle, almost tender process," he says. "It involves a lot of touching, rubbing and pushing."
The alligator´s cold-blooded metabolism is spectacularly efficient. "Over a year," Vliet says, "a 180-pound alligator´s total intake of calories will be one hundredth that of a human the same size. It will not only survive on that but will thrive and grow." In winter months, the animals stop feeding altogether. Even compared to turtles, gators have a low idle, it seems.
Adult alligators in the wild can withstand a surprising amount of abuse, from mercury contamination, to loss of a limb, to a year without food. But there are limits, as illustrated by the widely reported problems in Lake Apopka, near Orlando. In the early 1980s, the gator count there dropped from several thousand to just 400 or 500. Juveniles were particularly hard hit. The hatch rate of eggs plummeted, and the few hatchlings that emerged tended to have peculiar abnormalities, including off-kilter sex hormones. The problem persists. "We´re seeing feminized males and masculinized females," says Louis Guillette, a University of Florida reproductive biologist who, with colleague Tim Gross, has investigated the crash. "More than 80 percent of the Lake Apopka alligators we look at have these abnormalities."
The culprit is the lake´s badly polluted water, long affected by municipal sewage and agricultural chemicals--and further contaminated in 1980 by a huge pesticide spill. In controlled studies, the researchers discovered that applying the chemicals found in Lake Apopka to healthy alligator eggs from a relatively pristine lake caused the same abnormalities. In some cases, the embryos switched sexes. "Lake Apopka leads us to ask some hard questions," Guillette says. "What are we doing to the animals around us, and what are the consequences to ourselves?"
The biggest overall threat to the big reptiles, however, is habitat loss. Small wonder that they are a worrisome fact of life in Florida´s new lakefront communities that seem to sprout daily. Despite the creature´s malevolent reputation, only nine human fatalities due to alligators have been recorded in Florida over the past 30 years. Still, some 12,000 to 14,000 nuisance gators are reported to the state annually. Of these, 5,000 are captured and killed by specially licensed trappers.
"Every year, more nuisance alligators are captured than the year before," says South Florida nuisance-animal trapper Todd Hardwick, who calls his company Pesky Critters. "Human population in Florida is increasing while alligator habitat is decreasing. That means one thing: more alligators on golf courses, in swimming pools and on driveways."
Hardwick likes alligators himself. "I have to listen to people complain, ´I just bought a $300,000 house, and now an alligator has moved into the neighborhood!´ I have to explain, ´No, you moved into his neighborhood, ma´am.´" The reptiles seem happy to share the habitat with us, he finds, but most humans would prefer not to share with gators--and with animals larger than six feet, he adds, people are ill advised to try. No matter what else the future brings, Hardwick is confident of one thing: job security for the alligator trapper.
After his adventures in the Everglades, Massachusetts writer Doug Stewart reports he has new respect for alligators, airboats and black electrical tape.
NWF Priority: Restoring the Everglades
Once a healthy, four-million-acre "river of grass," the Florida Everglades has been reduced to half of its original size by several decades of unwise water management, urban sprawl and agricultural growth. In an effort to prevent further deterioration of the area and revitalize wildlife habitat, NWF and one of its affiliates, the Florida Wildlife Federation, are directing an aggressive grass-roots campaign in support of Everglades restoration. As part of their program, the two groups are working with government agencies and citizen groups to protect the "forgotten" western Everglades from destructive projects.