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Lizard Tales

Published: July 06, 2004

We work on introduced species. These are species that are found outside their normal native range.”


Dr. Todd Campbell’s blue eyes aren’t fully lit yet, but it won’t be long. If the world ever has known a top-notch scientist who isn’t passionate and excited by his work, Todd Campbell is not it. But at this point, he is merely warming to the topic at hand—his recently launched efforts to eliminate the Nile monitor lizard from the southwest Florida city of Cape Coral.


Not only is it really important to work on them because they’re second only to habitat destruction in their affects on native species,” he continues, momentum building, lights coming on, “and whole ecosystems can be altered by these introduced species, but you can also ask a lot of interesting ecological and evolutionary questions using introduced species, because you don’t need permits to collect them. So, I try to do both basic work and applied work in introduced species.”


The applied work must be where the biggest fun is. This high-energy assistant professor of biology hasn’t said as much, but he exudes it. And while the energy is high and the delivery loquacious, both are keenly focused, always, and never without significant substance. With all that waiting, the warm-up quickly spikes into the good stuff.


The Human Condition


Two years ago,” Campbell says, knowing exactly where he’s going, “I was told by a colleague that, during a trip to Miami to work on introduced lizards down there, I need to stop in Cape Coral and see the Nile monitors, because it’s really incredible what’s going on there. I didn’t know anything about it.”

“OK,” Campbell remembers thinking, “I’ll stop there for a couple days, get a hotel, and see if I can find some of these things.”

He admits to not expecting anything more than a minor population of individual lizards that had been released by suburban yuppies who had grown tired of the novelty of keeping their unruly exotic guests. But a surprise was on the subtropical horizon.


“What I found was trails and boroughs and scared residents and people who had had the things climbing on their roofs, eating their cats, taking goldfish out of their ponds, and cornering them in their garages.


“So, it was really interesting to me,” he says, as if that weren’t interesting enough, “from the human perspective, because studying introduced species is not pure biology. By definition, you’re studying the human condition, too, because we are the ones [responsible for introducing them]. If it’s an introduced species, it hasn’t done it on its own.


“Not only do we have the fact that the pet trade and the people who buy these things were the cause of this whole problem, but we’ve got this introduced species impacting humans in a very big way.”


Poised for Growth


Contributing to the problem is the fact that the aggressive African lizards thrive in their adopted habitat. Cape Coral is a residential former “bedroom community” to Fort Myers that has grown to more than twice the population of its older, better-known neighbor city. It extends over the southwest Florida mangroves in a sprawling maze of partially developed neighborhoods interspersed with canals and enclaves of undeveloped land.


Neighborhoods seem to spring up overnight like clumps of gleaming stucco toadstools—but with plenty of space in between. Rather than fill vacant space within neighborhoods, the trend from Port Charlotte to Cape Florida seems to be to start more neighborhoods, while never quite finishing any of them.


The result is a low-density residential mini-metropolis almost as “full” of vacant lots as it is houses, and Nile monitors just love vacant lots. They especially are keen on Cape Coral’s vacant lots, which tend to be backed by vegetated canal banks.


The city’s Web site lists a human population of 127,582, and boasts this additional description:


“With nearly 85,000 vacant home sites, 400 miles of canals, 3,236 miles of paved streets, and the second-lowest crime rate in the state for cities of more than 100,000 people, the Cape is poised for continued growth.”


Humans evidently aren’t the only ones who think so. But, while the site has an “owl cam,” an “osprey cam” and an “eagle cam,” the “ Nile monitor cam” is notably absent, and in fact, a search for “monitor” on turns up only the verb.


The community initially was developed in the 1950s, although the city’s population explosion didn’t hit until much later. Like so much of developed Florida, the land was not suited for human habitation until developers decided it could be, and took whatever measures were necessary to turn a swamp into a city.


“We call it ‘the scrape,’” says Campbell. “They basically took a marsh and a mangrove habitat, and scraped it out, dug it up, and placed the material off to the side to make uplands for building. As a result, you’ve got all these canals, and the whole city is fringed with mangrove habitat.”

The vacant lots and fields bordered by canals give Nile monitors a perfect place to call home, a home much more like their original habitat than any humans in the area can claim. In actuality, two introduced species are pitted against one another in a struggle for survival. For the humans, the situation might not be quite that dire, but it is dire enough. And as so often is the case, they have themselves to blame.


Tail Like a Bullwhip, Claws Like an Eagle


These are being sold at pet stores as little things like this,” Campbell says, showing a photo of a cute and cuddly little lizard about the size of your standard Florida gecko cradled gently in his hand.


“In a couple years, these things grow to a couple of feet, and they start getting really, really aggressive, and by the time four or five years goes by, you’ve got the five-footer that’s in my back yard.” (Yes, he had to keep just one—in a sturdy wire cage. Name? Thumper.)


“What you’ve got,” he continues, “is this animal with a tail like a bullwhip and claws like an eagle, and this business end up here,” he says, referring back to the photograph and flicking a finger at the creature’s head, “with a serious set of teeth. It can do a lot of damage.


“And they’re very-very-very bad pets,” he says with such sincere yet easy intensity that the redundancy gets no quarter. “They’re just really-really awful pets. People have them because of that reason sometimes—the big mean snakes and the big mean lizards. It’s a very sort of sexy thing to have a big mean critter. But they’re very bad pets, and the vast majority of people cannot handle an animal like this after it gets big. They just can’t.


“And the pet trade is lying to the public. You can walk into any pet store and ask them about the little hatchling Nile monitor that they have in a cage for $39.95, if it’ll make a good pet, and they’ll just outright lie to you: ‘They only get four feet long. Oh, yeah, you can keep it in a 55-gallon aquarium.’


“I’ve even had pet store owners say, ‘No, they’re mean when they’re young, and they actually mellow out with age,’ when the opposite is true. Only a very small percentage of the public can handle an animal like this as a pet. So, they get released.”


No good scientist can stand a blanket generalization for long, and for Campbell, his own is no exception.


“People who have pets and people who work in the pet trade industry have various attitudes, and most people are generally good. But there are bad apples out there, and some of those bad apples intentionally release animals to get populations established. They can later cull from those populations without having to deal with import laws and all that.”


As for ordinary residents who let the creatures go after they become difficult to manage, Campbell’s outlook is a bit more forgiving, attributing a combination of compassion, ignorance and, at worst, laziness to their solution.


"Thumper" is unusually tame on this day, Campell says. Still, handling him anytime is a handful, and Campbell recommends never trying it without heavy gloves, patience and experience.


“They’re doing the wrong thing, but they’re not doing it with malice, in general. They take the easy way out, and they let it go, and that’s emotionally sometimes very fulfilling,” he says. “Some people even think it’s the right thing to do: ‘Let it free! Let it free into the environment!’ Well, most introduced species don’t have a big negative impact out there.”

Most, he said, aren’t even able to establish themselves. Among those that have, he cites monk parakeets, those bright green squawkers of Florida’s skies, as an accidentally introduced species that is perfectly harmless. (They’re harmless here, he points out. Evidently, some have spread north, and the noisy winged beauties cause a lot of problems in, believe it or not, Chicago.)


Sexy Species


As to why the Nile monitors are concentrated principally in Cape Coral, Campbell can only speculate, but once again, he turns his suspicions to the retail pet industry. Possibly, a pet store in the area enjoyed particularly prolific sales of hatchlings. Perhaps more likely, someone saw pre-boom Cape Coral, sans residences, as the ideal place to establish a Nile monitor population that could be harvested for sales later. Again, the move would have been strictly profit-driven.


“If you don’t have to ship an animal from Africa,” Campbell reasserts, “it’s a lot cheaper—a whole lot cheaper to just go out and catch it. Here you’ve got your African species—a big, sexy species like a Nile monitor—right here. You can drive over to Cape Coral and catch them, and sell them for 300 bucks a pop. It’s a very big incentive.


“We don’t know if that’s what happened,” he again is quick to add. “There could have been a really bad tropical storm or hurricane that tipped over a breeder’s cage. Maybe one individual got out, a female that was gravid, from a breeding stock from a person who was very ethical.


“A lot of these invasions are totally unintentional. There are a number of scenarios you can imagine. It could be simply the random, chance occurrence that enough people bought these things from a pet store in the area and found them bad pets, and decided Cape Coral would be a really good place to let them go, because there weren’t very many houses. And eventually, given the large home range of these lizards, they started finding each other.


“The monk parakeet population that’s all over Florida literally is the result of a spill at the airport,” he says, returning to a favorite for illustration. “A cage broke open, and all the birds got out. It was one event.”


Hurricane historian Jay Barnes notes in Florida’s Hurricane History (University of North Carolina Press, 1998) that certain types of animals seem to get unearthed and redistributed by major storms.


“Alligators, snakes and rats were a menace in the weeks after the storm. Numerous snakebites were reported, mostly from the reptiles that had taken up residence in homes and furnishings. One truck driver had operated his vehicle for three days before discovering a rattlesnake coiled under the seat. The proliferation of rats was a health concern and prompted the state to implement a rodent control program. Five thousand pieces of poisoned meat were distributed over south Florida by boat and helicopter in an effort to exterminate the vermin.”


The passage is about Hurricane Donna, which blasted straight through the region in September 1960. While that storm came far too early to have delivered the monitors to southwest Florida (Campbell believes that the monitor invasion likely began in the area in about 1990) a certain infamous category-four monster named Andrew devastated south Florida in August 1992.


Could Florida’s biggest introduced-species headache be partly a long-range residual of its worst storm disaster? The timing is close, and the proximity is tantalizing, but the rest still is guesswork, and Campbell is certain the invasion began no later than 1990.


And either way, says Campbell, blame ultimately falls on one source.


“I’m really angry at the pet industry for putting me in a position to have to kill these spectacular animals,” he says, “whether it was intentional or not.”



No Flying Lizards


In any event, somehow, circa 1990, a Nile monitor invasion of Cape Coral began. There is no real guess as to how many may have been turned loose since, and in that decade-plus, procreation naturally has added to the ranks. A single female Nile monitor, Campbell says, may lay in excess of 60 eggs a year in maturity (starting at about 4-5 years of age), and a single “clutch” of 84 eggs has been recorded.


“They can reach reproductive maturity in two years,” Campbell says, at which time the typical adolescent female monitor will set down a first clutch of about 15 eggs.


Besides being obviously prolific, the hardy lizard also boasts a home range of two square miles, and can hold its breath for an hour at a time. It also is an outstanding swimmer and an expert climber. Hatchlings, in particular, spend most of their time in trees.


In fact, adds Campbell, “About the only thing they don’t do is fly.”


Without a thriving industry that harvests them for food and skins (one country in Africa eliminates some 800,000 of them each year in those pursuits, Campbell says), the Lee County Nile monitor supplies the second major population boom in the area.


Adding to their threat, as well as to their survival potential, is their appetite.


“They eat anything,” Campbell says. “Any kind of invertebrate—snails, clams, even oysters in some areas; any other kind of crustacean, crabs, fish, amphibians, reptiles, birds and mammals.”


They also are fond, he says, of bird eggs. They will eat burrowing owls and gopher tortoises, and as if to give deeper meaning to the phrase “eating them out of house and home,” will then take over the burrows excavated by their latest victims. Turtle eggs are on the menu, too, and in their native Africa, even dwarf crocodiles have been known to constitute meals for Nile monitors.


Smaller American alligators may be at risk, Campbell says, returning to the dangers that monitors pose to indigenous species in Florida. He adds that no positive impact speaks in favor of the lizards, “except for maybe the chance to see a really incredible animal in the open. But that’s what zoos are for.”


From Big News to a Really Bad Joke


Reaction to the eradication project came swiftly. Campbell and his colleagues sent out a press release to Fort Myers-Cape Coral area news media. That the story ever became national news may have been a bigger surprise than the news itself.

“Our idea was to contact the local press, so that we could have an article in the local newspaper, so that local people would call us back with monitor sightings. Very clear goal in mind: We wanted monitor sightings so we could go to people’s houses and set traps, try to catch these things, find out information about their reproduction, maybe their density, and get an idea of the magnitude of the problem quickly.”


The Associated Press liked the story enough to pick it up from the Fort Myers News-Press, and before Campbell knew it, he was getting calls from family in San Francisco and Kansas City by the next day, and e-mails from people in Canada who had read the story.


Animal Planet and National Geographic were next, followed by National Public Radio (on which he since has appeared three times) and PBS in Atlanta. The chaser came when Jay Leno used the story for a joke in a Tonight Show monologue on NBC.


“It was a really bad joke,” Campbell whispers, one hand to the side of his mouth in a mock effort to keep the whole affair a secret. “I don’t even remember the joke,” he concludes, still in a whisper, “but it was really bad.”


Bad jokes aside, Campbell appreciates the attention for the sake of his profession and its work.


“It’s nice, because it’s very rare for people in my field to get a lot of media attention. A lot of times, biologists do their work in isolation and objectivity, and rightly so. It’s supposed to be an objective thing, but conservation biology adds another whole level to science.


“You’ve got the science end of it, but you’ve also got an advocacy end of it, a subjective end where you’re trying to manage populations. If Nile monitor populations are bad, then it’s our duty to try to drum up support for somehow fixing the problem.”



Big Bad Players


Funded by $30,000 from the National Fish and Wildlife Foundation and another $20,000 from the Charlotte Harbor National Estuary Program, Campbell has built a small team to work the problem with him. So far, his cohorts include fellow UT assistant biology professor Mason Meers, herpetology Ph.D. candidate and part-time trapper Gregg Klowden from the University of Florida, and full-time trapper Zach Reffner of Cape Coral, and a pair of UT biology majors, Nathalie Briend and Anthony Chacour, just added to the mix as research assistants.

Predictably, some well-meaning individuals and groups do not like the work they have set out to do, which is to eradicate the Nile monitor in southwest Florida by the only available means, which is to trap them and humanely dispatch them with gas. (The latter chore is performed “ethically,” Campbell says, by a local veterinarian.)


“Three weeks after we started this project, there was a ‘Save the Nile Monitor Society’ in Fort Myers,” Campbell recalls.


The Fort Myers Herpetological Society even organized excursions to see the lizards.


“An hour after the first press release that we did, PETA—People for the Ethical Treatment of Animals—called. From their standpoint, it’s not the animals’ fault.


“But it’s also not the native species’ fault, either, and so, if we’re going to have to make a choice, we’re going to go with the native species. We don’t want, in any case, an introduced species to be the nail in the coffin of a native species.


“Some of these introduced species are really big bad players. They’ve caused literally the extinction of species. There are a 150 species of cichlid fish in Africa—the pretty cichlid fish that you would see in pet stores—that are gone now, gone forever, because of the introduction of the Nile perch into one lake in Africa.”


Campbell says at least one indigenous Florida species is at significant risk.


“It’s possible that Nile monitors could affect burrowing owls pretty substantially.”


Presumably, he says, Nile monitor hatchlings are vulnerable to alligators and hawks, but their density and propensity to procreate continue to increase their population, and once past the hatchling stage, there is little they have to fear from other species, with the exception of humans and adult alligators, both of which they can usually outrun or outmaneuver.


“They’re getting abundant enough,” he says of the monitors. “Their density is reaching that of what you would see in Africa. They’re the top predator in this new system.”


A Difficult Find


Confident that the lizards in fact number in the thousands in Cape Coral, Campbell and company have a difficult time encountering as many as residents seem to just by chance. The reason?


“They’re really smart,” Campbell declares. “They’re really intelligent lizards. They’re actually really intelligent even for some mammals. They control their world and what they are going to do. Most people don’t see them because of that—because they hear you coming, and they take off. They can run 18 miles an hour.


“It was very hard for us to figure out how to go look for them and find them. Generally, what we wound up doing is walking along the canal banks, and just very carefully approaching, and you can actually get a glimpse of them before they go in the water.”

Ironically, as Cape Coral stops spreading and starts filling in its empty spaces, the situation naturally will improve for that area. It’s what’s beyond that concerns the scientists.


“The sea-walling of all the canals is going to diminish the habitat for Nile monitors,” Campbell asserts, “so as build-out in this area occurs and the more seawalls there are, the less habitat there is for Nile monitors to burrow. So, it’ll get better as time goes on.


“But what we’re worried about is the monitors moving out of Cape Coral, and moving north, or just their population generally expanding and spreading out in concentric waves, just like any population would.”


The Only Answer


Eradication is the only viable answer, Campbell says, and there is no time like the present.


“With introduced species, the big mantra is ‘too little, too late.’ In almost every case, we look back at an introduction, and we say, ‘Gosh! If only we had had stronger quarantine methods at that time,’ or, ‘I remember when there was only a small population.’


“Given a reasonable amount of resources, like a small team of biologists and trappers, I think we can actually get rid of this population here, if they haven’t spread out into the natural areas too much.”



But if they have?


“Then we do have a too-little, too-late situation.”


And already, it appears that Cape Coral may not be the only trouble spot.


“There’s a population, we think, in Orlando. There’s a population in Miami.


The more we find out, the worse it sounds like it’s getting. There may be other populations established on the east coast, maybe even [elsewhere] on the west coast of Florida.


There have been a few sightings in Hillsborough County, he says.


“We don’t quite know about their geographic distribution yet. That’s another thing we’re trying to ask. Where are they? How far have they spread?


“These guys can walk easily a mile in a day. So presumably, if they ate themselves out of house and home in the general area of Cape Coral, and everybody’s cats were gone, and there were no more bunnies to eat, they could move pretty far.”


Fewer than 50 have been captured so far, but the trapping didn’t begin until January, and Nile monitors tend not to eat in cold weather.

“Thumper hasn’t eaten in a couple of months,” says Campbell.


Even though the project began in July, the first catch with bait was in early February. The early months were devoted to analysis and strategy. By the time a plan was in place, the weather had cooled down, and mating season (which evidently doubles as eating season) had run its course.


But as the weather warms up again this year, Campbell believes, the Nile monitors will warm up to the bait. Summer, he predicts, will spell major numerical success in the trapping effort.


“They’re going to start trying to put on weight and body mass for breeding,” he explains.


“Luckily, they’re pretty easy to catch with squid—the stinkier, the better. If that weren’t the case, there’s no way I would even try this.”


Beyond the immediate solution, Campbell also must consider the future. The last thing he wants is to finish eradication in one region only to be called upon to start over in another.


“If I have it my way, Nile monitors will be illegal to own. Other monitors are fine. Those other species are tamable. Croc monitors are nice. A savannah monitor is a wonderful pet. The same goes for a water monitor. They’re nice pets, so people don’t let them go.”