Where the Wild Things Were

by William Stolzenburg

  And nobody hammered the point more poetically than Aldo Leopold himself. In his opus A Sand County Almanac, he rolled the Kaibab and all the West’s deer irruptions into one defining parable:

  I have lived to see state after state extirpate its wolves. I have watched the face of many a newly wolfless mountain, and seen the south-facing slopes wrinkle with a maze of new deer trails. I have seen every edible bush and seedling browsed, first to anaemic desuetude, and then to death. I have seen every edible tree defoliated to the height of a saddlehorn. Such a mountain looks as if someone had given God a new pruning shears, and forbidden Him all other exercise. In the end the starved bones of the hoped-for deer herd, dead of its own too-much, bleach with the bones of the dead sage, or molder under the high-lined junipers.

  I now suspect that just as a deer herd lives in mortal fear of its wolves, so does a mountain live in mortal fear of its deer.

  Caughley

  But in 1970 there came along a wildlife biologist from New Zealand named Graeme Caughley to challenge Leopold and the Kaibab legend. Otherwise known as the eminent authority on Australia’s kangaroo population, Caughley was moreover an acerbic antagonist of shoddy science, whose idea of fun was to skewer cherished paradigms, then to “sit back and say to yourself, ‘Try to shoot that one down, you bastards.’”

  “Charming,” Caughley had once written of himself, “I am not.”

  When Caughley came upon the mountain that Leopold had built, he took a bulldozer to it. That famous Matterhorn peak of Kaibab deer had been constructed largely on loose estimates, Caughley chided. Leopold had not only lifted Rasmussen’s interpretation; he had then dramatized the drawing by sharpening the downside of the deer peak from a steep slide to a veritable cliff. The latter was the version that most textbook writers had faithfully reproduced—a fact Caughley graphically displayed to everybody’s embarrassment in the professional journal Ecology.

  Then there was the underlying logic itself, that the missing predators were largely to blame for the irruption. What about the huge exodus of livestock—some two hundred thousand sheep, some twenty thousand cattle—that had coincided with the plateau’s runaway population of deer? To Caughley’s mind, that sudden surplus of forage was at least as good an explanation for the irrupting deer as that of a few less wolves and cougars.

  “Data on the Kaibab deer herd in the period 1906–1939 are unreliable and inconsistent, and the factors that may have resulted in an upsurge of deer are hopelessly confounded,” Caughley wrote in his 1970 critique. “The study is unlikely to teach us much about eruption of ungulate populations.”

  Boom.

  It took a few years before the textbook writers and conservation historians caught up with Caughley’s critique, but as word got out, Leopold’s mountain was abandoned in droves. A raft of subsequent textbooks started expunging the romantic version of the Kaibab legend. Confessed professor C. John Burk, “I personally blench recalling instances—at least yearly for more than a decade—when I myself used, often dramatically and with gestures, the Kaibab example in a classroom situation … One still cannot contemplate the Kaibab incident without extracting some moral from its consequences; all things considered, Caveat emptor would seem as good as any.”

  In time, even Leopold’s sacred wolf-killing confessional took a bad tarnish. It was true that Leopold had begun his career preaching death to all varmints. And it was true that Leopold ended his career pleading for their salvation. But in between lay some shaky truths, not the least of which was the sacred wolf that Leopold had supposedly shot. The most famous martyr in conservation history might itself have been a myth. Leopold biographer Curt Meine could find no trace of it in the naturalist’s meticulous hunting journals. Granting benefit of the doubt, Meine concluded that the wolf killing must have come during a period for which Leopold’s diaries were confiscated, thereby placing the purported epiphany to sometime in 1909—an unfortunate date, given it wasn’t until 1941, after finally visiting the Kaibab, that Leopold completed his turnabout on killing predators.

  And so it was that the Kaibab legend limped into the twenty-first century—just in time to be revived by a few wolves recently returned to northwest Wyoming. If the news coming out of Yellowstone could be believed—if a large terrestrial ecosystem could teeter upon the fate of an apex predator—why couldn’t the Kaibab have happened as Leopold had described? In 2002, Dan Binkley of Colorado State University and three colleagues officially reopened the Kaibab case. And by the end of their second field season on the plateau, they were ready to see the textbooks rewritten once again.

  Binkley and crew looked at aspen and deer on the Kaibab, as Ripple and crew had looked at aspen and elk in Yellowstone. And like their colleagues farther north, the Binkley team found the Kaibab aspen quitting production in approximate synchrony with the killing of the Kaibab predators and the irruption of Kaibab’s deer.

  One could almost hear Caughley objecting from the grave: What about those gazillion sheep grazing the Kaibab?

  But this time it was the great critic’s turn to be called on the carpet. Caughley had misinterpreted the historical records, badly overestimating the sheep numbers. “There were never that many livestock on the plateau itself,” said Binkley, who double-checked the figures. “Livestock herbivory appears to explain none of the anomalies in aspen numbers.”

  In one serendipitous little sideline discovery, Binkley’s crew dug up a 1935 edition of Grand Canyon Nature Notes, containing a clue to the missing aspen: “In marked contrast to … the Kaibab Forest, one finds rather extensive reproduction of aspen in the vicinity of the Quaking Aspen Ranger Station.” It turned out a cabin had been homesteaded there in the mid-1920s by a Ms. E.Vaughn, whose family ran a few cattle, hunted cougars with dogs, and had built a corral. “Here a number of hounds are kept,” read the report, “and of course, no deer come near.”

  Binkley’s crew located the old corral, conveniently still flagged by the aforementioned grove of aspen. The scientists counted tree rings. The grove had sprouted soon after the fence went up in 1925, near the peak of the deer irruption. Outside the fence, no new aspen were to be seen for the next half century.

  “Was Aldo Leopold Right About the Kaibab Deer Herd?” asked Binkley and his coauthors in a 2006 issue of the journal Ecosystems. Putting all the pieces back together—the hunting records of predators swept from the plateau, the tree rings revealing aspen soon thereafter eaten to a standstill by what must have been a tremendous herd of deer—they ended with the following: “We suggest … that the story (and the history of the story) be reinstated in ecology textbooks.” The Kaibab legend breathed again.

  Cougar Cascade

  By the time the Binkley findings were heading to press, there was another study underway, just sixty miles north of the Kaibab in the canyon country of Utah, which was about to cast another strong vote Leopold’s way. Its investigators were none other than Bill Ripple and Bob Beschta, who in tracing Leopold’s countrywide register of deer irruptions, had come to the national park named Zion.

  A monument not unlike the Grand Canyon’s Kaibab, Zion is a ten-thousand-foot block of continental crust on the edge of the Colorado Plateau, long ago hoisted aloft and then cut from above by streams and great depths of time to form a dizzying land of kaleidoscopic sandstone cliffs and canyons. Zion was designated a national park in 1918, a mixed blessing that replaced a half century of homesteading in the bottomlands with a new culture of highways, foot trails, and tourists. By 1934, the yearly number of visitors had reached nearly seventy thousand, the bulk of them piling into the park’s namesake gorge, Zion Canyon.

  With the coming of the crowds went the cougars, and in the all-too-familiar sequence, the mule deer of Zion began amassing. The gallery forests began dying, the riverbanks began sloughing, and the deer took on a sickly pallor. As noted in a 1938 park service report: “The deer in Zion [canyon] are in very poor flesh and present a sorry spectacle. Professional wildlife visitors to the park this summer
have been unfavorably impressed by the unbalanced deer forage situation here.” By 1942, it was reported that “over-population of deer in Zion Canyon, with consequent scarcity of feed, is one of the major problems at present in Zion National Park … Vegetation is so over-browsed that it is in serious condition and there is danger of complete destruction.” That year, the park service resorted to shipping deer from Zion.

  This of course was familiar territory for Ripple and Beschta, with two critical and far-reaching distinctions. First of all, Zion’s was a food pyramid topped not by coursing packs of wolves but by solitary, stalking cougars. Felis concolor—cougar, mountain lion, catamount, panther—is by any name the fourth largest cat in the world and pound for pound the ranking giant killer, leaping from ambush, fangs breaking necks and severing vital arteries, credited with killing mice to moose, one on one. And whereby elk were the staple of Yellowstone’s wolves, mule deer were the standard fare of Zion’s lions.

  Zion National Park’s second distinction stemmed from a fundamental and fortuitous twist of natural history. Over the ridge from Zion Canyon, only nine miles as the raven flew, flowed a nearly identical creek and corresponding gorge but with a major difference. While the commercialized Zion Canyon honked and thrummed with the annual commerce of three million sightseers, the adjacent canyon of North Creek remained roadless backcountry, its towering walls echoing silence but for the lonely footsteps of a few hardy hikers. In large part for these reasons, hardly a sign of mountain lion was to be found in Zion Canyon, while the streamside sands of North Creek were pocked with paw prints and scats. The sister canyons offered mirroring views of life, differing solely in the one variable of most concern to the scientist seeking the trophic cascade: the presence of lions.

  These were not wolves, and this was not Yellowstone. If an ecological cascade were to be found here, triggered by such a vastly disparate predator as the cougars, in such starkly divergent environs as the canyon country of Utah, one would be left to ponder much broader concerns in the larger land of vanishing predators.

  Escaping the bustle of Zion Canyon, Ripple and Beschta hiked over the ridge and down the canyon wall into the backcountry of North Creek. As the two began the protocol they’d so often practiced at Yellowstone—the dry recitation of stream depths and tree diameters, calling out numbers amid the burble of flowing water—it became apparent there was something more going on in North Creek than an inordinate growth of cottonwoods. The two could not help noticing the contrasts in life between the sister canyons. Streams of butterflies sailed by—swallowtails and sulphurs, blues and satyrs, monarchs and skippers. They had to look to keep from stepping on the cardinal flowers and red-spotted toads. The stream banks were a scurry of canyon treefrogs and spiny lizards. The waters shimmered with speckled dace and other native fish of the desert stream. North Creek flowed with a lifeblood that had been drained from the canyon of Zion.

  The data sheets soon started filling with the names of flora and fauna. In addition to forty-seven times as many cottonwoods, there were three times as many lizards in North Creek, five times as many butterflies, more than one hundred times as many toads, more than two hundred times as many frogs. The disparity in cardinal flowers and asters grew to infinity, given the biologists couldn’t find a single flowering stem growing along their transects in Zion Canyon.

  Zion Canyon’s trophic cascade took an entire page to illustrate. Beginning with the incursion of humans running the lions out of the canyon, it ran to the irruption of mule deer, to the death of cottonwoods, to the dissolution of streambanks, to the disappearance of wildflowers, and the butterflies that once sipped their nectar and spun cocoons in their leaves, and the sparseness of lizards that had once chased the butterflies and scampered for cover among the shrubs, and the rarity of frogs and toads and desert fish no longer courting in the pools that were no longer there.

  From busloads of tourists to missing butterflies and bankrupt streambeds, Zion Canyon’s cascade had ended in what the ecologists called a catastrophic regime shift. Zion minus its lions had lost more than cottonwoods in the bargain; it had lost a community. And if not for a standard of purity surviving over the next ridge in North Creek, where cougars still reigned, nobody would have ever known the difference.

  Sixty miles south and sixty years before, Aldo Leopold may have stretched the facts in engraving the Kaibab legend. For that matter, he may never have even watched any fierce green fire dying in any wolf’s eyes. But artistic license aside, he may have gotten the message right just the same.

  As for Ripple and Beschta, never ones to accumulate moss, within the next two years they had blown the cover from two more supposedly sacrosanct refuges. In Jasper National Park in Canada and Wind Cave National Park in South Dakota they came to find the same disturbing pattern: Eradications of apex predators, dying trees, ecosystems sliding toward duller, less stable planes of simplicity. “Yes, we’re finding cascades just about everywhere we look,” said Ripple, who by then with Beschta was already on to another undisclosed site in their quest for ecological cascades.

  It had become almost too easy to put a finger on the map and find communities there cascading away through the void of missing predators. It would be another matter to imagine a plan audacious enough to reassemble all the missing pieces.

  TEN

  Dead Creatures Walking

  IN SEPTEMBER 2004, a dozen biologists gathered at a ranch in southern New Mexico to kick around an idea that in the simplest of terms would raise the American landscape from the dead.

  Their idea was to restore a certain character of life and wildness to what they saw as an ecologically eviscerated continent. They had seen for themselves the signs of sickness in the wake of the missing predators, in the waves of hoofed creatures and the withering forests and invading weeds. They had also seen signs of repair, in the reawakening of Yellowstone with wolves again at the top of the food chain. More to their point, they had come to realize grander and crazier possibilities. The fossilized bones of America revealed a land so recently rumbling with giants. It was a land of mammoths and five-ton sloths, herds of wild horses and bison with horns spreading six feet across. It was a risky terrain running with wolves and lions, with a cat bearing six-inch canines and a bear big enough to make a grizzly cower. To their imagining eyes, it was America at its full-blooded best. And their idea was to bring it back.

  One might imagine them dreamers. Many would more easily consider them kooks. But this was not a dream, and their ranks consisted of some of the most respected conservation scientists in their field. This was not even a new idea. Some of them in fact had been seriously contemplating this for a long time.

  Blitzkrieg

  One wintry weekend outside Montreal in 1956, a young postgraduate ecologist found himself hunkered inside against the cold, pondering death. Paul S. Martin was preparing a seminar on the biology of the Pleistocene, an epoch beginning 1.8 million years ago with the onset of its signature glaciers, and ending—as Martin was now reminded—with the sudden and sweeping disappearance of so many great animals. Martin began the weekend thumbing through the time line of mammalian evolution leading up to the Pleistocene. With every advancing epoch, Miocene to Pliocene to Pleistocene, twenty-four million to five million to nearly two million years ago, the fauna had tumbled by the score over a cliff of extinction. Each die-off was followed with a resurrection of sorts, an evolutionary reconfiguration that restocked the empty niches with new and equally fantastic life-forms, large and small, a revolving canvas of bestiaries. And then, near the end of the Pleistocene, the pattern took a twist that brought a double take from Martin.

  Again the reigning fauna had collapsed, but this time with a blatantly heavy bias. This time, the reaper had apparently handpicked the mightiest among the beasts. In contrast to the more random assortments that preceded them, the animals that disappeared at the end of the Pleistocene were almost without exception the largest of the lot. The cast had included Columbian mammoths, thirteen feet
at the shoulder, and herds of wild horses and giant bison. America had housed giant camels and a beaver as big as a bear. There was everybody’s favorite Paleolithic monster, Smilodon, the saber-tooth cat. There was a dire wolf and a rocket-fast feline called the American cheetah. There was a bear the shoulder-height of a moose with the leg-speed of a quarter horse, a creation to give anthropologists the night sweats.

  And yet so suddenly they were all but gone, with only a skeleton crew surviving. Prior to that night in Montreal, Martin had once entertained notions of a career as an ornithologist. That would now have to wait for some other lifetime. The next year Martin moved his family to Tucson to take a research post at the University of Arizona’s Desert Laboratory, where for the next fifty years he would work on solving the most contentious mass extinction since the dawn of humans.

  The Pleistocene die-off in itself was nothing new to science. Charles Darwin had puzzled over it as a green, twenty-four-year-old naturalist circling the globe aboard the HMS Beagle. “It is impossible to reflect on the changed state of the American continent without astonishment,” he wrote in his journal. “Formerly it must have swarmed with great monsters: now we find mere pygmies.”