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New York Exhibit Gives Insight into the World of Frogs - 2004-06-15


In New York City, a new museum exhibit explores the survival patterns of the many diverse species of frogs that can be found in nearly every environment on earth, from lush rain forests to parched deserts.

In a far corner of New York's Museum of Natural History, a team of frog experts has recreated the natural habitats of dozens of different kinds of frogs. The frogs lurk in their miniature ponds and hop around on tree branches, casting an occasional eye on the visitors who stare at them through glass windows.

A group of brightly colored, miniature reptiles called dart poison frogs form the centerpiece of the display. Decorated in potent yellow, blue and red colors, they are cute but the covering on their skin can be fatal.

"Because of these skin toxins, they are avoided by animals that otherwise might feed on them. They are very unpalatable and indeed they can make animals sick or potentially even die," says Christopher Raxworthy, the curator of the exhibit.

He explains the frogs convert low levels of poisons in the insects they eat into a skin coating that makes them dangerous. He says each of the frogs contains enough poison to kill 10 people.

"They don't really have to fear anything," he adds. "They have these bright colors to warn, the toxins to back up that warning and they are active during the day, strutting around and doing their stuff."

They are called "dart poison frogs" because indigenous people in northwestern Colombia rub their darts against the frogs' skin before using the darts to shoot prey. And while Mr. Raxworthy loves studying frogs in rainforests and jungles all around the world, he says these little creatures are the only ones that have ever given him reason to pause.

"I think always when you lick frogs to test their toxicity you know, you're always wondering whether this is going to be the frog that might really numb up your mouth or make you roll over," he says.

That's right. He said "lick." Researchers in the rainforest commonly place their tongues against the skin of potentially poisonous frogs to see if they taste toxic or not.

Contrary to popular myth, as visitors learn from touring the exhibit, you actually cannot get warts from kissing frogs. Medical experts say warts are usually caused by viruses or skin irritations.

Frogs help the environment by eating insects and contributing to pest control and some of their skin toxins are used to make human medicines. Because of encroaching civilization, the environment of the frogs is shrinking, leading to fears they may become extinct. Julian Faivovich is a scientist who has studied frogs for more than 15 years.

"There are some groups that we are aware of that are suffering because of human expansion or agriculture, like pesticides," he adds.

But more worrying to researchers, Mr. Faivovich says, are frog populations disappearing for mysterious reasons.

"Where no human impact at all can be detected, some populations started to decline in a very notable way, for example, in Costa Rica there are some frogs that haven't been seen in the last years and also [in] some areas that are very far away from human populations or any impact that you can measure and they are still disappearing."

He says experts believe fungal diseases may be to blame.

Constantly under threat from environmental changes and larger animals who want to eat them, many frogs will do whatever it takes to survive. One species, called the African bullfrog, adapts to the sub-Saharan climate by hibernating for up to eight months at a time during the dry season, then emerges to eat and mate when the rain comes. Budgett's frogs, a species found in Argentina, Bolivia and Paraguay arch their backs and howl like cats when confronted by predators. And that's not the only frog that shows similarities to another animal.

That's a pig frog, which gets its name because it makes noises that sound much like a pig.

Learning the language of the world's frogs has become a hobby for Mr. Raxworthy.

"One of my favorite calls is a frog in Madagascar. It's called a green tree frog that sounds a bit like a car siren but it does this whistle noise where it goes um, [whistles]. Another frog which is found in Madagascar does these wonderful grunt noises, sort of [grunts]," he says.

And Mr. Raxworthy says being able to imitate frogs is very useful. Once you know how a certain kind of frog sounds, you can identify it before you even see it.

"One of the fun things about these frog calls is once you learn them, for example, you can be in your truck driving along the road and you can suddenly catch a chorus going on in the background in the rainforest and you say, 'Oh, wow, look at that! Such-and-such-a species is found in this pond over here.' So it's a tremendous utilitarian tool once you've mastered the frog calls. Of course it takes a long time, though," he explains.

Studying frogs may be fun, but, as the head of the Natural History Museum, Ellen Futter, says, "In the inimitable words of Kermit the Frog, "It's not easy bein' green."

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