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LYN MILLNER ASKS: IS THE ENVIRONMENT CROAKING?
Published June 8 2009 By Lyn Millner
"Frogdesign" by Walter Fogel
The frog recordings below are courtesy of Lang Elliott, author of The Frogs and Toads of North America.
Win Everham snorkels in the swamps of Southwest Florida. He tells me it's like swimming in tea because the tannin from the cypress trees makes the water brown. If you're the first one in, he explains, and the silt isn't stirred up, the water is clear for ten feet, and you can see the roots of trees—the swamp's underwater architecture. He feels like an otter, swimming and twisting in and out and around the roots with the minnows and crayfish.
An ecology professor at the state university in Fort Myers, he's there to lead people on a nature walk or to measure the girth of a tree or to collect data for one experiment or another.
Barking Tree Frog
If you go anywhere with Win, it's a good idea to wear shoes you don't care about. Even if you go to a county park with well-defined paths or boardwalks, you'll probably leave the trail at some point—to wade through a stand of bald cypress, or take a shortcut to a pop-ash slough, or investigate some cool place it occurs to him to show you. He's so enthusiastic that people follow him, even those who don't think they are interested in ecology. And he's a good guide. He has left only four students behind in a swamp, and it really wasn't his fault.
Sometimes, he takes people to the Fakahatchee Strand, a swamp forest with slow-moving water that is making its way from Big Cypress Swamp out to the mangrove swamps that border the Gulf. The Fakahatchee is where Susan Orlean searched for ghost orchids with John Laroche, the orchid thief.
Most often, Win tromps around in his own neighborhood, a suburb between Naples and Fort Myers. He is a "disturbance ecologist." And there are plenty of disturbances where he lives and teaches—honeybees living in vacant houses, hurricanes lashing the shore, a black bear napping in someone's yard. Win is interested in both man-made disturbances and natural ones. Often there's no difference other than perspective. The napping black bear, for instance. Who disturbed whom?
I live down the street from Win in unincorporated Estero (Spanish for "estuary" or "marshy land"). Some people call it "Es-sterile" for its strip malls and gated communities and banks that share the same Mediterranean look, as called for in Estero's community plan: "barrel tile roofs, articulated facades, building ornamentation, embellished windows, columned porches, and parking lots placed in the rear of the property." One of my friends, visiting us from Miami for the first time, saw our condo community, Villagio, and said, "Well, it certainly isn't going to offend anyone."
The patches of land that haven't been developed are covered in tall grass, palmetto scrub, and slash pine. It's a habitat for alligators, burrowing gopher tortoises, bald eagles, sandhill cranes, armadillos, herons, ducks, and frogs.
During tourist season, twenty-nine thousand people live in these twenty-one square miles. Eight years ago, there were only ninety-five hundred people. The animals haven't yet adjusted to the reality that we've taken over their land. Since last summer, marauding coyotes have killed and eaten three pet dogs and injured three others. The firemen on Imperial Parkway report seeing a bobcat occasionally.
One winter, dead snakes began appearing on the road leading to the Fort Myers airport. Scads of them. Win and a fellow scientist at the university, David Ceilley, counted more than four hundred and fifty along a one-mile stretch. Banded water snakes, ribbon snakes, garter snakes, a few water moccasins, a crayfish snake, a red rat snake, a Florida brown snake. A hundred of the snakes were too damaged to identify. Win only saw one live snake, which he chased off the road into a ditch. The question was, Why all the dead snakes?
"At first," Win says, "I thought they were trying to cross the road." He laughs because he realizes it sounds like the joke about the chicken.
"But there was not a single snake on the other side of the road. It became clear that once they got onto the pavement, they just sat."
He and David determined that the snakes were coming onto the asphalt to get warm. The weather had been down in the fifties at night and in the eighties during the day. The snakes were thermoregulating, as Win puts it. Why were there so many? Because this happened shortly after the airport expansion, Win and David's theory is that the expansion trapped the snakes in that area.
Win and David talked to airport officials, but it was too late. Most of the snakes were dead, so doing something like putting asphalt pads along the road "would be like closing the barn door after the horses are gone," Win says.
If you're willing to believe that a frog worries about anything other than his next meal or his next tryst, then certainly you'll accept that he thinks humans are trying to stamp him out. Every day, on average, Lee County adds fifty more people. They plow down pastures, put up buildings, redirect water, and flatten frogs under their tires. The last thing a frog would suspect, on a wet Florida night in full chorus with his fellow frogs, is that humans are clustered on the side of the road, cupping their ears and listening to them.
But, led by Win, humans are listening. Each month during the rainy season, June through September, Win drives a prescribed route along the Interstate 75 corridor of south Lee County. Most of the people who go with him are students from the university, but anyone in the community is welcome to tag along. The group stops at twelve pre-arranged locations, to record the conditions—traffic noise, wind speed, temperature, humidity, amount of standing water, and level of development—and then listens for three minutes for specific species. They submit their information to the Southwest Florida Amphibian Monitoring Network, which compiles data sent in by likeminded groups from all over the region.
The best time to listen for frogs is at night, because that's when they call the most. On a wet Wednesday evening in July, I joined the group in the parking lot of the South County Regional Library at dusk.
Win was late. He often runs behind because he has a full schedule. In addition to teaching, he does community outreach, conducts research, writes papers, supervises undergraduate and master's students, and so on. He never says no, his wife tells me.
In the parking lot, as the froggers prepare, they show one another their new gear: clip-on headlamps, Maglite flashlights, waterproof clipboards, and various gauges, like thermometers, humidity monitors, and wind-speed trackers. David Ceilley (the guy who investigated the airport snakes with Win) brings a parabolic microphone, which he sets on the hood of his truck. Jorge (pronounced "George") picks it up and tries it out. The mike is a concave metal bowl with handles you hold like a steering wheel. He brought it so he could hear the more distant, softer frog calls, though he knows he's not allowed to document what he hears through it. That's outside of the NAAMP protocol, NAAMP being the North American Amphibian Monitoring Program.
We coat ourselves with mosquito repellent, stand in a circle, and listen to frog calls on an iPod that Rob Leisure, one of the students, brought. Because there's no speaker for the iPod, we pass the earphones around, taking turns listening. Meantime, Rob and Julie Van Horn, another student, imitate their favorite frogs, ones we are likely to hear tonight.
I have to admit that up to this point, I assumed all frogs sound pretty much alike. I couldn't even distinguish them from crickets.
But they make a wide variety of sounds. There are frogs that sound like marbles clicking against one another in an echoey bathroom. Frogs that sound like a person dragging a moist finger across the surface of a balloon. Water softly dropping into a cistern. Quacking ducks. Baby chicks. Fax machines. Morse code. Maniacal laughter. Hound dogs with hoarse throats.
Green Tree Frog
They are nearly impossible to imitate, but Rob and Julie give it their best shot. Rob imitates a pig frog—"Arrr, arrr, arrr"—which is supposed to sound like a low-pitched grunt. "Some people mistake it for a gator," he says. "I can't do it."
Julie's favorite is the greenhouse frog, the one that sounds like dripping water. "Crick, crick, crick." She isn't satisfied with her imitation. "You'll have to listen to it on the iPod. They like to live in potted plants, and they're about as big as your thumbnail."
Win speeds into the parking lot in a lumbering white van that belongs to the university. He is wearing a tie that's a bit too short and a strand of purple Mardi Gras beads ("A voodoo thing," he says). And his shirttail is out. He is nearing fifty and has gray hair that's short except for the rat tail in the back. There's a single stud in his left ear—a turtle in brushed silver.
"Everybody ready?" Ten of us pile into the van and head to the first stop.
Frogs depend on water. They absorb moisture through their skin. They also breathe through their skin as well as using their lungs.
"Their skin is like a living lung," one scientist said. "It's as if our lungs are hopping around."
Because they have thin membranes, they are sensitive to pollutants, ultraviolet radiation, and environmental changes. So scientists study frogs because they are early indicators of trouble. When a frog population decreases, it may signal a loss of wetlands or declining water quality, which are big concerns on the Gulf Coast. Frog populations are in decline all over the world.
There are also a lot of malformed frogs, more than scientists once thought. At Win's suggestion, I spent a recent afternoon looking at pictures of mutant frogs on the Internet. Frogs with missing legs, partial legs, split legs, and legs growing out of their regular legs. There was a frog with a third eye near its tympanum (ear). Others have missing eyes. Some have disfigured backbones. Extra toes. The strangest one I saw had three heads, all capable of croaking, and six legs. There's a video of it on YouTube that I didn't have the stomach to watch all the way through.
Malformed frogs point to something very wrong in the environment. What exactly that is, scientists aren't sure.
Stop one on the frog route is along a four-lane road, across from a Hess gas station.
Jorge and Corrie read the temperature and clock the wind speed, among other duties. Jorge is the most serious of the bunch. He is getting his master's in environmental science. His zeal for amphibians is matched only by his love for the Cleveland Browns.
"Ready?" he asks, checking his watch. Everyone falls silent. "And we begin now."
An eighteen-wheeler whooshes by. A gasoline truck pulls into the station, belching and grinding its brakes. The driver hooks a hose to the underground tank and begins pumping. We hear crickets, but no frog calls.
When three minutes are up, Jorge calls stop. You'd think they'd be disappointed at not hearing frogs, but they aren't.
"This is useful data," Jorge said. "And it's par for the course in this location. There's a lot of development going on here lately. It's important to document that there used to be frogs here, and there aren't anymore."
Jorge and Corrie rate the traffic noise as a "four," meaning that it's constant with no breaks. Traffic noise isn't something that the NAAMP tracks in isolation. This group added it as a category because they want to study its impact on amphibians more at some point.
Frogs may have been calling at the Hess station, but we couldn't hear them. More importantly, the frogs may not be able to hear one another, in which case they won't mate and reproduce. Noise from traffic is changing frog behavior. Some males select resonant tree holes to call from so females are more likely to hear them.
The scientists who lead the fourteen monitoring routes in Southwest Florida have conjectured that development is the main reason some frog populations are dwindling. Development, as opposed to global environmental change.
Development causes water runoff; there are more deepwater retention ponds. And these affect frogs. Some frogs like the results—specifically, the ones that depend on permanent water. But those with a need for seasonal water are out of luck, and their numbers are declining. Over the last eight years, the data support this trend. The populations have changed most dramatically in the areas with the most rapid human development. To oversimplify: Humans come, frogs go. Win and his students documented this in an article that appeared in the journal Florida Scientist.
Cuban Tree Frog
At the Hess station, Jorge looks up from his clipboard, "Just heard a Cuban," referring to a Cuban tree frog.
"Can't write it down," Win says. They only record the frog calls they hear during their three-minute window.
"I know," Jorge says.
Over the course of the night, we'll hear a lot of Cuban tree frogs. They've invaded Southwest Florida and are spreading north. They make a lot of different sounds: squeaking doors, cackling, a finger against a balloon, a small barking dog, a threatened cat, a rasping snore. Cuban tree frogs eat anything they can fit in their mouths, including native frogs. They change colors, from green, bronze, and gray to sickly tan or white. They secrete a toxin that makes them unpalatable to predators. And they do well in disturbed areas.
Sometimes, Cuban tree frogs enter houses through plumbing pipes. You'll hear stories of people going to the bathroom and getting a scare when they see one of these bug-eyed creatures staring at them, motionless, from under the rim of the toilet. Cuban tree frogs also hang out around backyard fishponds, lighted patios, and on highway billboards.
You can find instructions for killing these frogs on many frog-related websites. Rub benzocaine ointment along the frog's back, seal it in a plastic bag, freeze it overnight, and then throw it away.
Stop eight is near a construction site where a church is going up. We stand on an overpass and face a wetland, careful to avoid the black widows that have spun webs along the girder of the bridge.
We hear Florida cricket frogs—the marbles clicking together. Then something exciting happens.
"Southern leopard frog," Jorge whispers.
"No way, dude," Win whispers back. He and Jorge wave to the other scientists along the bridge. David nods; he heard it. They listen intently.
The Southern leopard frog is one of the species that's been declining in this area. This puzzles scientists because it doesn't fit the
water theory. This frog needs permanent water, so it should be happy with the recent development. But things are much more complex than water level and human development. For instance, Cuban-tree-frog tadpoles may be eating Southern-leopard-frog tadpoles.
Southern Leopard Frog
Southern leopard frogs are sometimes harvested for the frog legs served at restaurants. They are often dissected in biology classes. But neither of these is happening in Southwest Florida.
I can hear only the clicking-marble frogs. David moves closer to me to help. We wait a long time. Jorge calls time. And then we hear a staccato chirp from just one frog.
"That's it," David whispers.
It's a soft, maniacal chuckling and then balloon rubbing and then more chuckling. Some have described the Southern leopard frog's call as an evil-clown laugh.
"I don't think we've ever got leopards here before," Win says.
It's eleven o'clock, and we head to the university campus for two stops.
Even though we hear plenty of frogs, we only see one all night, just off the boardwalk leading to the dorms. It's amazing that anyone spots it, because it's so small. Win says it's a squirrel tree frog, sometimes confused for a green tree frog. There's a sort of lip underneath the frog's eye. If the lip is yellow, it's a squirrel. This one is a baby, Win says. They grow to three times that size.
"It goes to the students' keg parties," Rob jokes.
"Yeah," Win says. "It's socialized."
Win began the frog monitoring as a cool thing to do with his sons. His younger son, Lucas, is especially fond of reptiles and amphibians. Like his father, Lucas has a tail of long hair past his collar. For his science project one year, he and Win tested the effects of hurricanes on lizards, gluing plastic lizards to a bush, strapping the bush to the roof of the family's Oldsmobile Silhouette, and speeding down Corkscrew Road.
Lucas scoops lizards off the sidewalk and keeps them in cages in his bedroom, alongside his rare newt and two geckos. On the Everhams' back porch, also in cages, are a Honduran milk snake named Juliet and a California king snake named Stripey.
But after a year or two of frog monitoring, the boys found other hobbies to occupy their time. Girls. Clarinet lessons. Game Boy. Win was hooked, though.
"Every time we stop and collect information, even when we don't hear frogs, it's a piece in this puzzle. We're trying to find some kind of a pattern. It seems like not a waste of my time when I can see how it's all going to fit together. That's what made me want to be a scientist."
"Plus, chicks dig the frogs," Jorge says and laughs. "Very important. Guys that can make the frog impressions score big with the chicks."
"What's your most impressive frog-mating call?" I ask him.
"Eastern narrowmouth toad," he says with no hesitation. He makes a sound like a bleating lamb—"Wahnn. Wahnn."
"It's like they're whining," he says.
"That's really good, dude," Win says.
"I have a lot of practice, being a natural whiner."
We fall quiet in the van. There's only the white noise of the air conditioner, which is blasting to keep the heat and humidity at bay. We drive past the new mall, Gulf Coast Town Center. The signs are brightly lit, even at this late hour. BEST BUY. OUTDOOR WORLD. COLD STONE CREAMERY.
Something else occurs to Win about why he does the frog monitoring.
"It's nice to know the sounds. When you go out at night, you hear distinct calls and you feel more connected to nature because you recognize them."
"I'm a chick who digs frogs," Julie says from the back of the van. We all turn around and look at her because this is the most she has said all night.
She tells us about the frog that got her interested. An Australian White's tree frog named Sticky. He was her pet for nine years.
Sticky's default color was avocado green, though he could change to a dark banana brown, depending on the temperature. He was three and a half inches from snout to rear. And about once a week, Sticky scraped off his outer layer of skin, using his arms and legs, sort of like he was shedding a sweater. He pushed all of the skin into his mouth and then swallowed it. As a result, his skin was always shiny and he was sticky to the touch, hence the name.
"I miss hearing him call when it rains," she says. "He could hear the crickets outside the window, and he would call all night long. And I think he was lonely because he never had a girlfriend."
At the last stop, before we're even out of the van, Jorge hears the narrowmouths, his favorites.
"Narrowmouths are good," he tells me. "They are a nice, native, water-dependent species."
We begin our final listening session. Cars zoom past, but there are breaks in the traffic, during which the sounds seem to swell. In addition to the bleating of the narrowmouths, we hear a loud chorus of oak toads. If you don't know your toads, you'd mistake these for crickets, but they're quite distinct once you realize what you're listening to. It's a piercing sound like peeping baby chicks. You wouldn't guess that the oak toad is the smallest toad in North America. Along the middle of its back, there's a light stripe that gets darker when the toad is cold and lighter when it's warm. Oak toads are a good sign, too, Win whispers. And their populations are holding steady in this area. The narrowmouths are kicking butt, more than doubling in the years that the group has been monitoring them.
A pickup truck with a diesel engine pulls up alongside us and slows, nearly drowning out the narrowmouths. The driver rolls his window down and hollers, "What are y'all doing?"
Win lifts a finger to quiet him. The man leaves his engine running and waits. The froggers frown, cant their bodies toward the wet field, and cup their ears. When time is up, Win explains it to him.
"Oh," he says. "I thought you were looking for a dead body." Seemingly disappointed, he puts the truck in gear and drives away.
"We get a lot of that," Win says. "I mean, people don't think we're looking for a dead body. Usually, they're just curious. We've had them get out of their cars and listen with us. Or they'll come along on the next monitoring trip. I like that."
We're done for the night. Back in the van, Win switches on his flashlight, aims it at the clipboard, and makes some notes with his pen, which is a replica of a frog in full stretch.
"What kind of frog is that?" I ask.
Win considers the pen. "It looks a little like a squirrel tree frog, except that it doesn't have a distinct yellow lip. And no actual squirrel tree frog has red eyes."
He puts the van in gear but leaves the dome light on so Jorge and Corrie can finalize their notes. It's nearly one a.m. We drive to the library.
Within a year, the bumpy road we're on will be smooth and wide and brightly lit. The design and right-of-way permits are complete, and the county is taking bids on the construction. But for now, it's dark. We are a lighted, metal box of humans traveling through the night, as hundreds of oak toads peep full blast from the ditches and flatwood ponds.
Issue: Best of the South 2009
Tagged with: environment florida frogs nature
Locations: I-75 Corridor South Lee County
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