Tracking the Vanishing Frogs: An Ecological Mystery.

• Author: Bright, Chris

When my wife recalls the summers of her childhood, in a village in the South Korean countryside, she can still hear the nightly, ear-numbing racket produced by the frogs in the rice paddies. The croaking was so loud and so constant that people labored not to pay attention to it, for the sake of their sanity. Today, the frogs no longer sing in South Korea's paddies. To many middle-aged Koreans, their silence is a mournful thing--a mute reproach for a 30-year pesticide binge.

There may be other parts of the world where the frogs sing only in the memories of the middle-aged. Certainly there are many places where the paddies, ponds, and forests have fallen silent more recently. By 1990, a growing number of biologists had begun to suspect that these thousand little tragedies were parts of a single, much larger drama--and one that seemed to be unfolding with menacing speed. This is the story that Kathryn Phillips sets out to tell in Tracking the Vanishing Frogs. A science journalist, Phillips spent nearly three years following biologists around in the field as they looked for frogs, toads, and salamanders. She read their papers and attended their conferences. And she spent hours interviewing them, along with amateur frog breeders, U.S. Fish and Wildlife Service officials, and other people whose lives, for various reasons, are full of amphibians.

The class Amphibia includes frogs, newts, salamanders, toads, and a group of worm-like subterranean creatures called caecilians. Amphibians are among the oldest terrestrial vertebrates. The first members of the class appeared some 365 million years ago. Those creatures bore no close relation to modern amphibians, but frogs emerged perhaps 200 million years ago. Frogs must have serenaded the dinosaurs and hopped away at their foot fall. Today, there are about 4,500 amphibian species, distributed throughout the globe, except in the polar and desert regions. Every year, a few new species are added to the rolls.

It's difficult to understand what is happening to amphibians because for most species, we aren't sure where they are supposed to be and how many of them should be there. There is some evidence, for instance, that wild fluctuations in population size may be normal for some species, so a sudden scarcity might just indicate a bad but perfectly "natural" year. And there are many populations that are doing very well. The evidence for global decline is therefore a matter of anecdote. But the anecdotes are overwhelming: 10 percent of Australia's frog species went into decline during the 1980s; Brazil's Reserva Atlantica has lost eight of its 13 frog species since 1981; amphibian die offs have been reported in Denmark, Peru, India, Canada, the United States, and at least 11 other countries.

That an entire class of animals--and one as durable as Amphibia--should suddenly go into decline is ominous to say the least. Some biologists argue that certain amphibian...