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Research Magazine > ARCHIVE > Winter 00 > Article

Vanishing Reptiles
by Catherine Gianaro

Floating down Upper Three Runs Creek as it snakes through a cypress thicket to the Savannah River, you’re surrounded by the sights and sounds of nature: the graceful wingbeat of a snowy egret, a subtle ripple from a water turtle, the incessant buzz of a paper wasp.

An inescapable feeling of life pervades this South Carolina blackwater swamp.

So why are so many of its denizens dying?

“Current evidence suggests that amphibian and reptile declines, which are exacerbated by burgeoning human populations, constitute a worldwide crisis,” said Whit Gibbons, an ecology professor at the University of Georgia’s Savannah River Ecology Lab (SREL) in Aiken, S.C.

Gibbons is well-positioned to know. His lab’s research in the wetlands and wilderness of the U.S. Department of Energy’s Savannah River Site — a nuclear materials facility — qualifies as the longest continuous study of amphibians and reptiles on the planet.

What they’ve learned not only confirms the findings of other scientists, but also uncovers new — and potentially frightening — outlooks on the environment.

For more than a decade, scientists worldwide have chronicled a decline in the number of frogs and other amphibians. Because these creatures are very sensitive to environmental pollutants, their decline was seen as a harbinger for potentially wider ecological problems.

Now the attention has turned to their close cousins: reptiles, such as lizards, snakes and turtles. Although they don’t share the same permeable skin or reproductive characteristics — such as laying eggs in water — they appear to be as vulnerable as amphibians. Around the globe, they seem to be affected by the same environmental forces — and perhaps even to a greater degree.

“It became apparent to us the importance of finding out how serious the threat was to reptiles because there are many more reptiles in the world than there are amphibians. It turns out reptiles have far more environmental problems than do amphibians,” Gibbons said. “There are many, perhaps hundreds of species of reptiles that could go extinct throughout much of their range within years — not centuries, not decades, but years.”

Gibbons said that reptiles are an integral part of natural ecosystems and that protecting reptiles is of great importance to biological diversity. “The bulk of our natural heritage is non-game species,” he said. “It is those species that we depend on, yet so many of them are taken for granted. I don’t think we can do that anymore.”

Of the 7,150 reptile species worldwide, 70 are listed as endangered and 18 are threatened; of the 4,680 amphibian species, 17 are endangered and 9 are threatened, according to the U.S. Fish and Wildlife Service. “Not to take away from the amphibians’ problems, but reptiles are in much worse shape,” Gibbons said.

Cold-Blooded Culprits
Researchers blame six culprits that for years have threatened both amphibians and reptiles: habitat loss and degradation, environmental pollution, disease, global climate change, newly introduced species that compete with natural species for food and habitat, and unsustainable hunting and “harvesting” by humans.

Habitat loss is the largest single factor in reptile decline, Gibbons said. “I’m talking about irretrievable loss, like when you put in a shopping center. Well, that’s the end of your reptiles that were there. But if you manage land properly, animals can adjust to a lot of that.”

However, even when part of a habitat, such as a wetland, is protected, the surrounding dry-land habitat that reptiles need is often not protected, SREL research scientist Judy Greene said. “Most of these animals use the terrestrial habitat. They only come into the wetlands to breed.”

The scientists label commercial harvesting as the second largest problem for reptiles. “That’s something that doesn’t affect amphibians very much because most don’t have commercial value,” Gibbons said.

But reptiles certainly do. For instance, 90 species of Asian turtles are collected in huge quantities in Singapore and Cambodia for shipment to Chinese restaurants, where they are considered delicacies. “That’s a third of the total number of species of turtles in the world, some of which are going to be extinct within 10 years,” he said

On the other side of the world, box turtles are being over-harvested as well. In one year, Louisiana shipped 40,000 of them overseas for the pet trade. The box turtle population in the United States cannot sustain that kind of removal, Gibbons said. “To the credit of the Louisiana legislature, they voted unanimously to stop the commercial shipping of box turtles. But now that Louisiana has a law, the pressure on box turtles increases elsewhere. Of course now they’re going to start removing them from Alabama and Mississippi.”

Gibbons argues that, while human use of reptiles is not necessarily bad, such use should be sustainable — allowing a species to re-populate itself to the same level within a few years.

For example, an estimated 115,000 leatherback turtles — Earth’s largest reptiles — nested on the world’s beaches in 1980. By 1995, the global population had plummeted to a mere 30,000 because of exploitation in the Atlantic Ocean, according to SREL scientists.

“These are animals that have been around for 200 million years. They’re not newcomers,” Gibbons said. “But in just 15 years, the population size had decreased nearly 75 percent.”

Invasive species introduced into an area can spell danger for reptiles as well. For example, the Galapagos tortoise is now near extinction largely due to the unintentional introduction of rats, which destroy both the young and eggs of the tortoises. The new predators made their way to the Galapagos Islands as stowaways on ships.

The recent popularity of reptiles as pets also contributes to their decline. This past August, the U.S. government extradited a man it calls an international wildlife smuggling kingpin and charged him with illegally trafficking in half a million dollars worth of protected reptiles. Keng Liang Wong of Penang, Malaysia, allegedly spearheaded an international wildlife smuggling ring selling about 300 animals, including one of the rarest tortoise species, the Madagascan spurred tortoise.

Interpol, the international police agency, estimates that the illegal wildlife trade approaches $6 billion a year. Reptiles sold on the black market range in price from $900 for three Bengal monitor lizards to $20,000 for the exotic Komodo dragon.

“People who have more money than brains will spend thousands of dollars for some of these animals,” Gibbons said. “This guy offered me $10,000 for our albino canebrake [rattlesnake],” which was caught in a local resident’s yard and given to SREL. “It’s the only one known in the world, and I’m sure he would have sold it to someone else for $100,000.”

SREL’s long track record
In the struggle to preserve these species, the scientists’ first weapon is information. At SREL, researchers often go to great lengths to study the creatures that live along the waterways and wetlands of the Savannah River Site.

With radio receiver in hand exploring the outer marsh of Ellenton Bay — one of 300 distinct wetlands on the Savannah River Site — Gibbons whispered “Do you hear that? It’s probably about a hundred yards in there.” The object in question was a hognose snake that scientists had tagged with a transmitter to track its movements.

The methodical beep of the transmitter reported not just the animal’s location, but its body temperature: the hotter the animal, the faster the beep.

“He’s at 29. That’s pretty slow, which means he’s in a burrow somewhere. If he were out on a day like this, it would be well over 35,” Gibbons said.

Other traditional research techniques used on the site are pitfall traps and drift fences, which have been checked daily, without interruption, since the autumn of 1978, making SREL’s research the world’s longest continuous study of amphibians and reptiles. (See Frog Watch, page 14.)

These traps — actually buckets in the ground — are set 30 feet apart all the way around the bay; animals entering or leaving the bay are herded by two-foot high drift fences so that they fall into the buckets. “More than half a million animals have been caught coming in and out of here,” Gibbons said.

Each bucket contains a large sponge, which serves as a safety net or watering hole for those caught. “If the bucket dries out, [the sponge] retains moisture,” he said. “If the bucket is full of water, often you find a mouse or something sitting on top [of the sponge] like a little island.”

SREL researchers have been tracking animals this way on the site for nearly a quarter of a century. In 1978, the Department of Energy built a waste processing facility at Sun Bay. To understand the environmental impact of the new facility, scientists began studying Rainbow Bay, which is very similar to Sun Bay. “Those traps [at Rainbow Bay] have been checked every day since 1978,” Gibbons said. “Sun Bay, meanwhile, is a parking lot.”

Although the protected wetlands on the Savannah River Site haven’t changed much over the past two decades, the research technology has. To track animals more efficiently, SREL scientists now inject a glass-encased microchip — including a bar code with a unique identification number — underneath the animal’s skin.

The variety of research tools used on the site has enabled scientists to examine the travel patterns of various animal species. “For instance, normally when it rains, narrow-mouthed toads will be in the outside buckets because they’re coming into the wetland to breed. But southern toads are in the inside buckets because they’ve already bred, and they’re coming out,” Gibbons said.

“This is the type of study we really need more of,” he said. “How are we supposed to find out why these animals are in decline when we don’t know anything about their natural biology? Where do they go? How much land do they need? How long does an individual live?”

So much is not known, Gibbons admitted. “The Discovery Channel and the like have given the wrong impression. We find out these little mysteries, and that’s what they put on television. But what they don’t tell you are the millions of mysteries that we don’t know,” he said. “Like we don’t know why the southern hognose snake is in decline. The eastern species is not declining. These two species are very similar, so why is one having a problem and not the other? What’s the difference between what they eat, or where they lay their eggs, or how far they travel? That’s one thing that we are finding. The southern hognose snake doesn’t move very far. He doesn’t even cover the course of a square mile.”

Yet this species has inexplicably disappeared from most of its natural habitat. “They have not been seen in Alabama and Mississippi for 18 years,” Gibbons said. “And in over half the state of Georgia, they have not been seen for five years.”

SREL researchers also are studying the diamondback terrapin, a small turtle found along the southern coast of the United States. “Our studies on Kiawah Island show that these animals are being killed probably by the hundreds, maybe thousands, every year with recreational crab trapping,” Gibbons said. “People throw out the traps to catch crabs, and they just leave the traps there until they return on vacation. Well, these traps are designed to catch crabs, which can breathe under water. Turtles can’t.”

SREL researchers are creating a database of the distribution and population information of the 101 species of reptiles and amphibians found at SRS. “A lot of different studies have been done on the site over the years,” Greene said, “and we’re trying to make sure that all of the information is consolidated because it’s very valuable.

“It’s the most extensive collection of reptile and amphibian data in the world with a sample size of more than a million reptiles and amphibians,” she said, adding that the data soon will be accessible to scientists across the globe via the Internet.

What can we do?
But even with such an extensive database from which to draw, scientists still face an uphill battle to determine why so many reptile species are in decline — and to do something to reverse the trend.

“The first step was to identify the problem and to communicate to the scientific community that much more information is needed about this decline,” Gibbons said. “We need to pursue investigations on some of the particular species or groups that we know are, or we are suspicious of, having problems.

“The second step is to communicate this problem to the general public,” he said. “It’s the public’s responsibility to be supportive by redirecting more state and federal funds to go to research and education related to reptiles.”

A greater understanding of such ecological problems is propelled from programs like PARC — the Partners in Amphibian and Reptile Conservation. Formed in 1999 to develop strategies for the long-term conservation of amphibians, reptiles and their habitats, SREL’s PARC is supported by numerous organizations, including the departments of Agriculture and Transportation, the U.S. Fish and Wildlife Service and, most recently, the Disney Wildlife Conservation Fund.

“Scientists understand the need for development and want to learn better ways to reduce its impact on the environment,” Gibbons said, which is why he hopes to recruit more developers to join PARC.

“[Developers] need to educate those who work with amphibian and reptile conservation,” he said. “PARC is trying to come between the two extremes. We aren’t trying to preserve everything, but we can’t develop everything either.”

Environmental education is a necessity, according to Gibbons, but first you need the right attitude. And that’s not always easy to change.

“But I’ve seen it happen,” Gibbons said. “I’ve had snakes brought in for me to identify for 30 years. Early on, nearly every one of them was dead. Nowadays, people bring in live snakes, they bring in photographs or they just call us on the phone and describe what they found in their backyard. It’s a slow process, but it works.”

“The attitude that we have to adopt is that these animals are part of our natural heritage and that this is something that people need to be concerned about,” he said. “If these animals are having problems, then who’s next?”

For more information, access http://www.uga.edu/srel/.

Catherine Gianaro, who has served as editor of Research Reporter for the past two years, is an award-winning freelance writer and editor based in Chicago. She also is a former UGA assistant director of research communications


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Alligator snap trap

Researcher Jimmy Hill with an alligator snapping turtle, a species that has been drastically reduced in numbers because of commercial harvesting for restaurants.

























Florida alligator

There are many, perhaps hundreds of species of reptiles that could go extinct throughout much of their range within years — not centuries, not decades, but years.

--UGA ecologist Whit Gibbons