By Beverly Peterson Stearns and Stephen C. Stearns

Yale. 269 pp. $30

Before human beings developed, say Beverly and Stephen Stearns--she a journalist and he a zoology professor--fossil records show that most species lived for 1 million to 10 million years before becoming extinct, and no more than 10 kinds of animals and plants vanished each year. Called the natural or "background" rate of extinction, it's a sad index from which to measure just how much environmental destruction has been wrought in the past few centuries. Today the most conservative estimates calculate that from 10 to 100 times as many species are extinguished each year.

The Stearns offer about a dozen case stories of endangered species, tales of the social forces that have driven them to the edge of extinction, and the scientists and environmentalists who fight to keep them alive and reproducing. It's a fascinating collection and a physically attractive one, too; each page of the book carries a small illustration of the species in question.

Natural habitats in the Third World now face extraordinary pressures from expanding societies, leading to declining animal populations. In the Ivory Coast's Tai National Park, a band of chimpanzees studied for decades fell from more than 80 animals when first encountered in 1979 to around 30 by the spring of 1997. Disease--most likely Ebola--killed many of the animals. Illegal poaching is thought to have taken many more. Chimps are considered prime "bushmeat," and from 1992 to 1994 the human population around the Tai doubled after an influx of refugees from Liberia. Pascal Gagneux, a young zoology doctoral student, observed, "What scared me so much the first time I went to Africa was that you realize that by actually leading a very modest life in terms of material and energy consumption, these people threaten animals."

Suburban sprawl increasingly infringes on open space and wildlife in the industrialized West. In 1990 Texas developer Jim Bob Moffett planned a 4,000-acre, mixed-use commercial and residential project on top of the Edwards Aquifer in the hill country south of Austin. The aquifer fed Barton Springs, a local swimming hole, and home of its own species of salamander. By tapping the aquifer, Moffett's plan threatened both the springs and the salamander.

Austinites fought a bitter war to save both. A 1986 municipal ordinance trying to control suburban sprawl was so weak that in the next four years, every one of the 600-plus projects proposed was approved. "It was really a fraud on the people of Austin," said Bill Bunch, an environmental attorney. A special 1992 Save Our Springs ordinance curtailing construction in watersheds received 64 percent of the vote. A lengthy legal battle over the ordinance eventually went to the Texas Supreme Court, which upheld its restrictions. Unbowed, developers enlisted Republican Sen. Kay Bailey Hutchison to introduce a rider stopping the Environmental Protection Agency from listing new endangered species for over a year. (Environmentalists had petitioned the EPA to list the Barton Springs salamander.) Only after the Save Our Springs coalition won two lawsuits against the EPA was the salamander listed in 1997, providing increased protection to the animals and their habitat. By then SOS researchers estimate that Austin developers wanting to build over the Edwards Aquifer had received at least $900 million in infrastructure subsidies. It's a telling story of how difficult it is to fight the political and economic interests behind sprawl.

Even when government agencies make concerted efforts to save animals, poorly conceived conservation plans can backfire and lead to steep population declines. In Hawaii, rancher Cynthia Salley grew increasingly suspicious of U.S. Fish and Wildlife Service efforts to study the island's only native crow, an endangered species called the 'Alala. Biologists appeared only during the crows' nesting season, and after years of watching them climb trees to photograph the birds, she grew alarmed. "Common sense," Salley declared, dictated that no matter what diseases afflicted the crows, "human interference was accelerating the downhill slide." Salley subsequently closed her property to the Fish and Wildlife Service. Environmental groups sued, claiming that she violated the Endangered Species Act. As the trial neared its conclusion, a National Research Council report vindicated Salley's approach. The crow population subsequently stabilized at a low level.

Overall, the case studies carefully documented by the Stearnses portray a world where ecosystems are being seriously disturbed with devastating consequences. The question they raise is whether societies have the will to change, and allow other creatures to live, or whether all the nature reserves of the future will become, as scientists fear for Tai National Park, "a nice national park on paper" but in reality empty of animal life.

James William Gibson, professor of sociology at California State University, Long Beach.