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May/June 2000 issue	In this issue Table of Contents Editor’s Notebook Inside Story Reverberations Feature: Water Curious by nature

The oregon spotted frog of British Columbia’s Lower Mainland makes a point of avoiding risks. Seldom seen out of water, it prefers the safety of the marsh, where its shiny, dappled skin merges imperceptibly with the liquid interplay of light and shadow. During the breeding season, when the songs of other species ring boldly through the night air, the male Oregon spotted frog croaks furtively, under the surface.

Yet these evolutionary precautions are proving inadequate against the unprecedented dangers of the present. At home only in a narrow coastward strip that once extended from southwestern British Columbia to northern California, the Oregon spotted frog (Rana pretiosa) is in terrible trouble. Already absent from California, it is endangered in both Oregon and Washington. Last fall, it was granted the same tragic designation in Canada.

The calamity of the spotted frog has caught everyone unawares. Until very recently, no one even knew that the species existed, much less that it needed help. In the past, the Oregon spotted frog had been lumped together with its look-alike cousin, the Columbia spotted frog (Rana luteiventris), which is more widely distributed in Western Canada and the United States. Although people had noticed that the westernmost population had particular breeding habits — preferring warmer water and slightly earlier egg-laying dates than its inland relative — no one had taken much notice of these differences. It was left to David Green (now the curator of vertebrates at McGill University’s Redpath Museum and the chair of the Committee on the Status of Endangered Wildlife in Canada) to clarify the frog’s family tree. By analyzing the tissues of spotted frogs from various localities, he showed in 1987 that those along the Pacific fringe were different from the rest of their tribe. In 1997, the Oregon spotted frog was established as a species in its own right, with special adaptations to West Coast life.

Not until Green and other researchers set out to study the "new" frog did they face the disquieting truth. In the years since Green identified the frog’s family tree, the species had all but disappeared. A unique and irreplaceable genetic lineage was about to vanish. In Canada, for example, historical records placed the species at several sites in the Fraser River lowlands. By the late 1990s, all were vacant. After an intensive search, three new sites were found, one on Department of National Defence land near Aldergrove and two in sloughs near Agassiz. The total estimated adult population of Oregon spotted frogs in Canada currently stands at fewer than 300.

These circumstances are, in Green’s words, "really miserable." And they become even more troubling if we broaden the frame to include what is happening to amphibians in other parts of the world, for the poor Oregon spotted frog is not alone. Over the past decade, Green and other amphibian specialists have been shaken by an onslaught of alarming reports. A spate of amphibian extinctions in Australia. Massive die-offs in Costa Rica. Declines and disappearances that affect even the most pristine wilderness areas. In the Sierra Nevada mountains near Yosemite National Park, five of seven species have vanished or dwindled into worrying scarcity. In parts of the St. Lawrence lowlands, frogs are suffering high rates of gruesome deformities. In the mountain valleys of southeastern British Columbia, the once-abundant northern leopard frog (Rana pipiens) is in danger of vanishing. Although many amphibian populations naturally experience dramatic ups and downs, it is unheard of for so many species in so many places to plummet simultaneously.

At one time, scientists suspected that these effects might all be the result of global causes such as ultraviolet radiation, acid rain or toxic pollutants. While any of these factors may be important in a particular case, it has become apparent than none of them is universally to blame. Instead, amphibians around the world are suffering local declines because of the many and varied ill-considered actions of humankind.

"It’s just us, you know," Green says ruefully. "We should have seen that from the start. It is the many subtle spin-off effects of the things we do that cause problems for amphibians, both here and elsewhere."

In the case of the Oregon spotted frog, for example, the fundamental problem appears to be loss of habitat. To breed successfully, the female must lay her eggs in the shallow margins where the wetland spills out over the shore during spring flooding. Over the years, these marshy edges have been successively "reclaimed" for farmland, strip malls and roadways. And the mighty Fraser River, which formerly surged over its banks each year to replenish the marshes and sloughs, is now constrained by dikes that channel the water straight to the ocean.

The habitat that does remain is often of poor quality - another unintended result of human activities. Years ago, for example, someone introduced a plant called reed canary grass (Phalaris arundinacea), never imagining that it would choke the sloughs with its impenetrable mat. And the people who imported bullfrogs to start a frog-leg industry could scarcely have guessed that refugees from their failed project would one day prey on the last surviving members of an endangered species.

"The crucial first step in addressing a problem is to know that it exists," says Green, a determined optimist. However dire the situation may be, "at least we are in a position to do something about it." He is encouraged by the fact that a Canadian recovery team for the Oregon spotted frog was assembled last fall and that a recovery plan is now being developed. In the short term, its aim is to ensure that the surviving frogs are protected from further harm. The work undertaken so far includes classifying wetland habitat, finding sites suitable for reintroductions and raising eggs through to the juvenile stage.

So there’s a glimmer of hope in the wetlands of British Columbia, a possibility that the Oregon spotted frog may survive the travails of our century. But when we consider the prospects of amphibians as a whole, this reassuring light fades to shadow. If amphibians are in trouble, it is because we have taken too many careless risks. How quickly can we evolve into masters of stewardship?

Candace Savage is a Saskatoon-based writer and author of 18 books on wildlife, environmental issues and other subjects.

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