Croak

Editorial Notebook

April 19, 2003

OH, TO BE A FROG this time of year. On the first warm days, to emerge from hibernation to seek water. To fill the dusk with calls, high and low. And all this a prelude to procreation.

But in recent years, this march of life has been colored by other, more troubling signals from frogs. In a wide variety of ecosystems all over the world, among many species, scientists have noticed frog population declines or even collapses and more and more frogs with profound deformities.

The declines first began to show up in the 1980s and early 1990s -- even in relatively untouched areas -- from Costa Rica to Australia to California. Then in 1995, some Minnesota schoolchildren came across farm ponds with a high incidence of northern leopard frogs with extra hind legs, or no limbs, or lacking an eye. Since 1995, deformities -- including frogs with both male and female sex organs -- have been found in 60 species of frogs, toads and salamanders in 46 states, at rates as high as 80 percent.

The overall extent of these problems is hard to quantify because the well-being of frogs hasn't been rigorously surveyed for as long as, say, that of birds. But given frogs' vulnerabilities -- their eggs are unshelled, their skins are permeable, and they can't travel far -- they're now considered the environmental equivalent of the proverbial canary in the coal mine.

And what they're signaling isn't good. Each reported decline or deformity may arise from a particular combination of causes, but they generally stem from lost or altered habitats due to development and waters polluted by pesticides and fertilizers. Global warming, acid rain, increased ultraviolet radiation and parasites are often believed to be in play.

At the Patuxent Wildlife Research Center, biologists in the last few years have begun tracking the health of frogs across much of the country -- employing dozens of volunteer observers to travel set routes at set times and record the intensity of calling from various species. Founded in 1936 as the nation's first experimental wildlife station, the center is a startlingly pristine, 12,800-acre belt of forest, wetlands and meadows right in the middle of the Baltimore-Washington corridor near Laurel.

There, Robin Jung, a U.S. Geological Survey biologist, this time of year regularly visits vernal ponds -- forest depressions that temporarily fill with water -- to monitor frogs' health. Donning high boots, she gingerly walks through a small, 2-foot-deep pool looking intently for floating sacks of gel-like egg masses left by reproducing frogs. This wet spot was dry last spring, but frogs tend to return to the same places, she says, perhaps via a magnetic homing ability. The plan is that -- over many years and all kinds of conditions -- such surveying here and elsewhere will yield a more precise idea of the damage done to frogs.

In the meantime, Ms. Jung says, there are obvious steps that can be taken, particularly reducing the use of the cocktail of fertilizers and pesticides put on farm fields and lawns -- which rains drive into wetlands and frogs' life cycles. One of the most widely used agricultural pesticides all over North America, atrazine, is now suspected of causing those hermaphroditic frogs, and the federal Environmental Protection Agency is under pressure from environmental groups to ban it -- a decision that may be made this year.

During the biblical exodus, recounted Wednesday night at Passover Seders across the world, there's usually mention of the plague of too many frogs visited upon a long-ago pharaoh in retribution for oppression. Thousands of years later, a different sort of human wrongdoing may be bringing us the opposite -- a plague of too few frogs.

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