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Gone: Mass Extinction and the Hazards of Earth's Vanishing Biodiversity

By the end of the century, half of all species on Earth may be extinct due to global warming and other causes. Who will survive the world's dwindling biodiversity, and why?

I SPOT THE WHOOPERS en route to Arizona's Chiricahua Mountains, one of the 40 ranges collectively known as the Sky Islands—a landscape currently at the forefront of endangered species efforts. The Sky Islands are located at the convergence of four great ecoregions: the lower-elevation Sonoran Desert and the higher elevation Chihuahuan Desert, as well as the temperate Rocky Mountains and the subtropical Sierra Madre Occidental, which together funnel life from north and south, introducing pop-up biodiversity through changes in altitude. Some 4,000 plants and half the breeding birds in North America reside here.

The Chiricahuas are a Sky Island range 20 miles wide, 40 miles long, and rising nearly 10,000 feet. Composed of striking pink rock, they're the eroded remains of volcanic ash and pumice that erupted 27 million years ago, since cut by wind and water into whimsical feats of balance the Apaches called the Land of Standing-Up Rocks. The range is dissected by deep drainages that harbor unlikely kaleidoscope forests of sycamore, oak, juniper, pine, cypress, and madrone, alongside yuccas, agaves, chollas, ferns, mushrooms, grasses, and mosses.

It's a botanical mash-up, part mountain, part desert, part grassland. I can hardly take it in, moving fast, on foot, in pursuit of Kim Vacariu, who sets the pace down a trail that crosses and recrosses the flood-tumbled rocks of the South Fork of Cave Creek. He hikes lightly in what amounts to his back yard, telling me stories of the Chiricahua Apache, who, in their last year of existence here, down to only 39 men, women, and children, eluded one-quarter of the U.S. Army by running full speed at night across the desert floors linking the Chiricahuas to other Sky Island refuges.

Vacariu is the western director of the Wildlands Project, the conservation group spearheading the drive to rewild North America—to reconnect remaining wildernesses (parks, refuges, national forests, and local land trust holdings) through corridors, on a continentwide scale. The idea came into being 15 years ago, a hybridization between activism and science, when Earth First founder Dave Foreman teamed with Michael Soulé, professor emeritus at the University of California-Santa Cruz and one of the founding fathers of conservation biology.

Rewilding is bigger, broader, and bolder than humans have thought before. Many conservation biologists believe it's our best hope for arresting the sixth great extinction. E.O. Wilson calls it "mainstream conservation writ large for future generations." Because more of what we've done until now—protecting pretty landscapes, attempts at sustainable development, community-based conservation, and ecosystem management—will not preserve biodiversity through the critical next century. By then, half of all species will be lost, by Wilson's calculation. To save Earth's living membrane, we must put nature's shattered pieces back together. Only megapreserves modeled on a deep scientific understanding of continentwide ecosystem needs hold that promise. "What I have been preparing to say is this," wrote Thoreau more than 150 years ago, "in wildness is the preservation of the world." This, science finally understands.

The Wildlands Project calls for reconnecting wild North America in four broad megalinkages: along the Rocky Mountain spine of the continent from Alaska to Mexico; across the Arctic/boreal from Alaska to Labrador; along the Atlantic via the Appalachians; and along the Pacific via the Sierra Nevada into the Baja Peninsula. Within each megalinkage, core protected areas would be connected by mosaics of public and private lands providing safe passage for wildlife to travel freely. Broad, vegetated overpasses would link wilderness areas split by roads. Private landowners would be enticed to either donate land or adopt policies of good stewardship along critical pathways.

It's a radical vision, one the Wildlands Project expects will take 100 years or more to complete, and one that has won the project a special enmity from those who view environmentalists with suspicion. Yet the core brainchild of the Wildlands Project—that true conservation must happen on an ecosystemwide scale—is now widely accepted. Many conservation organizations are already collaborating on the project, including international players such as Naturalia in Mexico, national heavyweights like Defenders of Wildlife, and regional experts from the Southern Rockies Ecosystem Project to the Grand Canyon Wildlands Council. And Vacariu reports that ranchers are coming round, one town meeting at a time, and that there is interest, if not yet support, from the insurance industry and others who "face the reality of car-wildlife collisions daily."

At its heart, rewilding is based on living with the monster under the bed, since the big scary animals that frightened us in childhood, and still do, are the fierce guardians of biodiversity. Without wolves, wolverines, grizzlies, black bears, mountain lions, and jaguars, wild populations shift toward the herbivores, who proceed to eat plants into extinction, taking birds, bees, reptiles, amphibians, and rodents with them. A tenet of ecology states that the world is green because carnivores eat herbivores. Yet the big carnivores continue to die out because we fear and hunt them and because they need more room than we preserve and connect. Male wolverines, for instance, can possess home ranges of 600 square miles. Translated, the entire state of Rhode Island would have room for only two.

Vacariu leads me to a bend in Cave Creek where clusters of maple trees shed red leaves into the eddies, a place as ephemerally beautiful as a haiku. The scars of flash floods surround us, yet tranquility abides. The first campaign out of the Wildlands Project's starting gate is the Spine of the Continent, along the mountains from Alaska to Mexico, today fractured by roads, logging, oil and gas development, grazing, ski resorts, motorized backcountry recreation, and sprawl.

The spine already contains dozens of core wildlands, including wilderness areas, national parks, national monuments, wildlife refuges, and private holdings. On the map, these scattered fragments look like debris falls from meteorite strikes. Some are already partially buffered by surrounding protected areas such as national forests. But all need interconnecting linkages across public and private lands—farms, ranches, suburbia—to facilitate the travels of big carnivores and the net of biodiversity they tow behind them.

The Wildlands Project has also identified the five most critically endangered wildlife linkages along the spine, each associated with a keystone species. Grizzlies in the lower 48, already pinched at Crowsnest Pass on Highway 3 between Alberta and British Columbia, will be entirely cut off from the bigger gene pool to the north if a larger road is built. Greater sage grouse, Canada lynx, black bears, and jaguars face their own lethal obstacles farther south.

But by far the most endangered wildlife linkage is the borderlands between the United States and Mexico. The Sky Islands straddle this boundary, and some of North America's most threatened wildlife—jaguars, bison, Sonoran pronghorn, Mexican wolves—cross, or need to cross, here in the course of their life travels. Unfortunately for wildlife, Mexican workers cross here too. Of late, Vacariu says, these immigrants have been traveling up the Chiricahuas. Men, women, and children, running at night, one-gallon water jugs in hand.

The problem for wildlife is not so much the intrusions of illegal Mexican workers but the 700-mile border fence proposed to keep them out. From an ecological perspective, it will sever the spine at the lumbar, paralyzing the lower continent.


HERE, IN A NUTSHELL, is all that's wrong with our treatment of nature. Amid all the moral, practical, and legal issues with the border fence, the biological catastrophe has barely been noted. As if extinction is not contagious and we won't catch it.

Vacariu and I drive to Douglas, Arizona, just south of the Chiricahuas. There's already an older border fence here, a hodgepodge of Marine Corps steel landing ramps, concertina wire, and steel beams, all scrappily patched and welded, burrowed under in places, then reinforced with dirt piles that look like cat scratchings. Here and there doors are cut through. Elsewhere, stark white crosses stand as markers of someone's death. Every quarter mile or so, we encounter a lone Border Patrol officer napping in his SUV.

We drive the American side along a dirt road. The fence has been upgraded with motion detectors and floodlighting fit for a gulag. Lights are as much an abrasive to biodiversity as a road or a fence, blinding amphibians, disorienting birds, and disrupting the hunting behaviors of carnivores from snakes to coyotes. We motor to the end of the wall, to the Chiricahuas' eastern Sky Island neighbor, the Peloncillo Range. To the east, the border is marked only by a barbed-wire livestock fence.

Because we can, we step across into Mexico, into a desert stretching as far as the eye can see. It looks grazed but otherwise untouched, though the fence line is littered with empty water bottles: the fill-up station before a trip north into the dry land where travelers don't ask for sustenance.

Jaguars also cross here, Vacariu says, including a recent sighting of what some think might be a female, raising the possibility of the first jaguar births north of the border in decades. But the new fence calls for a far more imposing set of parallel walls surrounding a fully paved two-lane highway. If built, it will end the tentative, hopeful forays of jaguars and much else northward into these parts. Concerned, the Wildlands Project and Defenders of Wildlife organized workshops between government agencies and conservation organizations, hoping to put ecological concerns on the security agenda.

When we step back through the fence to the U.S. side, a weary-looking young man approaches on foot from a dusty track in the Peloncillos. In Spanish, he asks if this is the United States. Yes. Where exactly? We point at Douglas just down the road. He brightens, taps the Kellogg's logo on his vintage 1950s shirt, and says he's headed back to work. I tell him there are sleeping Border Patrol agents on his route. He's not worried.

I have no doubt that not even the Great Wall of Arizona will stop him. Invariably, the youngest, fittest, and most ambitious men and women of Mexico will find a way around. All the new fence will really arrest is the flow of nature's immigrants.


IF, AS SOME INDIGENOUS people believe, the jaguar was sent to the world to test the will and integrity of human beings, then surely we need to reassess. Border fences have terrible consequences. One between India and Pakistan forces starving bears and leopards, which can no longer traverse their feeding territories, to attack villagers.

The truth is, wilderness is more dangerous to us caged than free—and has far more value to us wild than consumed. Wilson suggests the time has come to rename the "environmentalist" view the "real-world" view, and to replace the gross national product with the more comprehensive genuine progress indicator, estimating the true environmental costs of farming, fishing, grazing, mining, smelting, driving, flying, building, paving, computing, medicating, and so on. Until then, it's like keeping a ledger recording income but not expenses. Like us, Earth has a finite budget.

Past sunset in Big Bend's Chisos Mountains we sit around camp in near darkness, alert to the fact that we'll be sleeping in the home of hungry mountain lions and bears—recently returned to the United States from across the Rio Grande. Suddenly the hush is cracked by an eerie sight. A flock of 50 ravens flies overhead, literally wingtip to wingtip in rare unravenlike silence except for their feathers zippering the quiet. They circle above us—a squadron of black ghosts—before sliding from view over the precipice of the south rim.

We speculate, in darkness, on this strange encounter. Are the ravens evading peregrine falcons, as some birds do, in tight, soundless flights? Are they preparing for night travel? It's a mystery we don't want to solve. Not really. Through awe, nature corrodes human hubris. May we evolve to feed on that ballast.

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