Rat Island

by William Stolzenburg

  Chapter 7

  BAJA CATS

  THE FOLLOWING DAY, Rowley Taylor and Bruce Thomas were packing up and leaving Breaksea Island as planned. Three weeks to the day after laying the first bait, they had finished a campaign that the naysayers had bet would fail. As a parting act of insurance, they left at each station a double dose of poison and a single apple. They would return the next month and periodically thereafter to check for signs of Breaksea’s rebirth, finding many; and to check the apples for gnawings, finding none. And indeed there would never be another rat found there.

  Breaksea had reconfigured the horizons. It had demonstrated, on a beggar’s budget and on hostile terrain, that a calculated dose of Kiwi audacity could beat the toughest, most intractable enemy of New Zealand’s natural heritage. The gray curtain that had closed on the Wellington rat conference twelve years before, conceding a world forever compromised by invaders, had begun to lift.

  With Breaksea in the bag, and their bait-station strategy now proven, Taylor and Thomas and their colleagues began eyeing bigger islands. And always with economy in mind. If an island was too big for the single storming of a little crew, they would whittle it down to size, parceling its overwhelming enormities into bite-size battlefields, deploying their bait stations in overlapping waves, one after the other, shore to shore—a rolling front, they would call it. By 1990 nearly forty of New Zealand’s rat islands had been cleared by hand. That year the emboldened Kiwis added the helicopter to their arsenal, raining poison from the air and sending New Zealand’s rat-free acreage on skyward trajectories.

  Out of hard luck and desperation, the defenders of New Zealand’s natives were pioneering a take-no-prisoners approach to biological conservation, saving island life by means of systematic eradication. And as it happened, would-be island saviors a world beyond were ripe to join the revolution.

  CLIPPERTON

  In the spring of 1989 a biology student named Bernie Tershy landed a job observing seabirds from a government ship cruising off the west coast of Mexico. The project leader had arranged for a stop at a lonely little island far out at sea. The island, named Clipperton, came with masses of seabirds and an interesting history of their occupation.

  Clipperton was a doughnut of nearly treeless land less than one square mile small and nearly eight hundred miles seaward from Acapulco. Sailors who began visiting the island in the 1700s were struck by this otherwise barren atoll so incongruously crawling with land crabs and stippled with nesting seabirds. The most conspicuous of the birds were two species of boobies—large, elegant high divers of the gannet family—nesting on Clipperton by the tens of thousands. The masked boobies of Clipperton constituted the species’ largest colony anywhere.

  Over the following two centuries the island underwent various exploitations and attempted occupations by several nationalities and one barnyard animal. American, Mexican, and French citizens came and went, but their pigs remained. Abandoned to their fates, the pigs made do by crunching their way through the scuttling fleets of land crabs and vacuuming up eggs and chicks from the seabird colonies. By the time biologists arrived in 1958 to survey the life of Clipperton, the crabs were all but gone, and the multitudes of boobies had been reduced to hundreds, the last of them huddled on a pig-free rock in the middle of the island.

  It so happened that a man who had come to count their numbers—an American ornithologist named Ken Stager, from the Natural History Museum of Los Angeles County—had come toting a shotgun to bag a few bird specimens for his museum. Stager saw what the pigs were doing to the birds, took it upon himself to remedy the situation, and turned his bird-collecting tool on them. He circled the island, counting fifty-eight pigs along the way, and shot every last one of them dead.

  By the time Tershy came to visit, the boobies were well on their way back, again amassing by the tens of thousands. (By 2001 surveyors would find Clipperton Island crawling under a living pavement of land crabs and inhabited by more than one hundred thousand boobies.) For him there was an epiphany in the little saga of Clipperton. Like so many of the conservation persuasion, Tershy in his fledging career had already tasted the creeping cynicism that invariably accompanied the losses. One could not live in coastal California, as he did, without witnessing the daily retreat of the wild places. Nor could one spend any appreciable time studying seabirds, the vocation Tershy was now courting, without repeatedly finding colonies decimated and littered with half-eaten carcasses.

  But here, in this simple story of Clipperton, was an inspiring revision of the tired and tragic ending. A lone man with a gun had restored a hundred thousand seabirds—had revived a moribund island ecosystem. Formerly resigned to the narrative of doom, Tershy suddenly envisioned himself a savior of species.

  Tershy’s closest colleague and sounding board was a fellow seabird biologist working in La Paz, on the southern coast of the Baja peninsula. Don Croll had studied seabirds across both hemispheres, from penguins in the Antarctic to murres in the Arctic. He and Tershy had both witnessed the same recurring carnage, of seabirds congregating so faithfully and fatally in an island’s broken seclusion. But on the flipside of that fatal flaw lay opportunity: Vanquish the threat, restore the masses. And the returns would multiply far beyond seabirds.

  Acre for acre there was no real estate in the world of endangered life-forms more precious than that of the ocean’s islands. Comprising 5 percent of Earth’s landmass, islands had come to harbor one in every five species of bird, mammal, and reptile. They had also shouldered 63 percent of all their extinctions recorded during human history. Island species had come to populate nearly half of the list of the world’s endangered. And most of those owed their endangerment to invaders.

  For a pair of conservation biologists wanting quick and massive impact, there was no calling more obvious than making the islands safe from invaders. And for Croll and Tershy, there was no better place to start than Baja.

  DESERT ISLANDS

  Eastward between Croll’s university on the Baja peninsula and the Mexican mainland lay the Sea of Cortez. Thirty miles west lay the Pacific Ocean. Within these coastal waters of Baja arose some 250 desert islands, generally distinguished by a scarcity of human settlements and a striking profundity of wildlife and wilderness.

  These were islands stark in appearance and astonishingly rich in their life-forms. On the sun-beaten beaches and sea cliffs, great colonies of seabirds would gather to nest. The isolation that drew the flocks had also modeled the islands’ resident individuals into peculiar forms—of sparrows and rodents, lizards and snakes, changing form from one island to the next. For modern-day wannabe Darwins, this was the magic kingdom.

  For the biologist concerned with saving the creations, however, the Mexican islands more resembled an inner-city emergency room at midnight. The islands came plagued by the usual cast of suspects from the mainland, the rogues’ gallery of burros, goats, rabbits, rats, and cats—grazers, browsers, meat hunters, and egg thieves, nibbling and gnawing and mauling their way through the evolutionary oddities and seabird masses. The list of casualties ran long. Recently gone were the Todos Santos rufous-crowned sparrow and the Todos Santos wood rat. Gone too were the San Roque white-footed mouse, the McGregor house finch, and the Guadalupe storm petrel. Nineteen species of native animals had been extinguished from the Mexican islands since the time of human settlement, eighteen of them with help from the modern menagerie of invaders.

  Croll and Tershy, as would-be island conservationists, found they weren’t alone. Beyond Ken Stager’s impromptu pig eradication on Clipperton, there was the ongoing campaign of the U.S. Fish and Wildlife Service, already years into liberating Aleutian seabirds from imported foxes. A team of independent biologists were even then readying themselves to eradicate bird-killing cats from Wake Atoll, in the western Pacific. And leading the way from Down Under were those pioneering Kiwis, escalating the offensive against the raiders of their island nation. Croll and Tershy believed they could do likewise for Baja.

>   Though the two soon migrated to faculty positions at the University of California, Santa Cruz, their focus remained fixed on saving the Mexican islands. They teamed with José Ángel Sánchez-Pacheco, a marine biologist from Baja with a kindred passion for island life and a behind-the-scenes talent for navigating the Mexican bureaucracy. Their plan took shape. They would seek their funders in the richer pockets north of the border, rally their Mexican colleagues south of it, and together, as an international team, save this beleaguered part of their world under a bilingual banner of island conservation.

  If they could somehow deal with the cats. The two most immediately troublesome invaders blocking their way were Baja’s rats and cats. With the blood-thinning brodifacoum on the shelves and the New Zealanders’ bait-station protocol now on the books, the conservationists already had the means and the model for confronting the rats. The cats, on the other hand, had yet to reveal any such silver bullet weakness. And as of 1994 there were twenty-six islands in northwest Mexico harboring menacing populations of them. The trio of conservation biologists found themselves woefully out of their league as cat hunters. Hence their first and most important hunt sent them in search of one.

  THE CATMAN

  Bill Wood was a retired trapper from the desert flanks of California’s southern Sierra Nevada. Wood’s specialty was the bobcat, a brawnier, stub-tailed cousin to the domestic cat. Over the years, Wood had honed his craft, earning a comfortable living trapping bobcats and selling their pelts. He had gained a reputation in Southwestern trapping circles as the king of bobcats. To some he had even come to embody his quarry, wiry and alert, right down to his probing feline eyebrows.

  The recipe to Wood’s success amounted to several decades of trial and error, and a dash of the intangible better described as art. Wood shunned gimmicks. His trap of choice was a standard Number 3 Victor leghold trap, featuring a pair of spring-loaded steel jaws triggered to bite upon the weighting of a cat’s foot. Beyond that, he parted company with the crowd. Where others baited their traps with veritable billboards of elaborate lures and witches’ brews of foul-smelling scents, Wood placed his faith in the subtle skill of placement. He had learned to read the land for its natural corridors and travel ways, the most likely paths by which the cat would cover its territory. If need be, he would delicately arrange surrounding rocks and bushes into chutes to guide the unsuspecting forefoot exactly to the center of his trap. Precision was key. An inch or two to either side risked a misfiring or an escape. Wood didn’t lose many cats to miscalculation.

  Or to the competition. Wood once found himself sharing a trapping territory with a man who had all but mined the mountain with traps. Wood laid out his three traps to the other man’s seventy-five. And every day on his rounds he would stop by the enemy’s camp for coffee, to listen humbly to yet another sad tale of rotten luck. The man eventually packed his gear and left, empty-handed and grumbling something about a scarcity of bobcats, unaware of the daily stash of pelts piling up in the back of Wood’s truck.

  Wood went to great lengths to guard his secrets. If he erred so much as to make a track in the sand, he would brush it out, to keep both bobcats and snooping trappers clueless of his presence. He had no intention of letting freeloading neophytes go “to school on him,” stealing with a glance the techniques he’d honed over years of dirt time. One trapper offered Wood a thousand dollars just to let him tag along. “Didn’t seem like a good deal to me,” Wood would later say. “I was making that much in a day.”

  Croll and Tershy caught wind of Wood’s ways with wild cats and called for his help. He was by then enjoying the retired life with his wife, Darlene, remodeling one of his several vacation homes, trapping as it pleased him, and indulging an addiction to fishing. But he was barely sixty years old and still harboring the adventurer’s itch. Now here was this stranger on the phone, offering to pay him for a stint on a sunny desert island in Mexico. And oh, by the way, the fishing was great. Wood, who spoke no Spanish and knew next to nothing of trapping feral cats, said what the hell, packed his gear, and headed south.

  Before sailing off on his Baja assignment, Wood, the hired catman, was briefed on the adversary. The feral cat was the vagabond version of the world’s most popular pet. Its alter ego, the domestic cat, had descended from Felis silvestris, the wildcat, a lithe little hunter originating in the Near East. It was there, some ten thousand years before, in the rich Mesopotamian river valleys of Iraq and Israel, that the first cultivated crops of wheat and barley began to replace the wild produce of hunting and gathering as the human’s basic sustenance. The prevailing speculations picture a pioneering wild cat wandering into one of the rudimentary villages of the dawning age of agriculture, drawn by the rats and mice foraging in the first farmer’s new grain bins. The farmer, quickly tiring of the pilfering rodents, grew to appreciate these wild little predators lurking about. And when the resident she-cat eventually had kittens, the kittens eventually became pets. It was a bargain for both. The cat got her mouse, the farmer got her grain, and both even came to enjoy each other’s company on the side. In the shrewdest of evolutionary plays, the wild cat domesticated itself unto the wealthiest provider in the animal kingdom.

  Over the next nine thousand years, progeny from that domestic cat—and perhaps from a handful of others hitting independently upon the same winning ticket—would come to number more than half a billion. More so than the appeasement-driven dog, the domestic cat retained its wild independence, tiptoeing a fine line between purring lap cat and hissing spitfire, a certain wildness that would serve it well whenever the interspecies marriage went sour. Cats could be abandoned just about anywhere and make do. They sailed the Atlantic with Vikings, sailed the Pacific with Captain Cook, explored the subantarctic with sealers. They were commonly presented as goodwill gifts to native islanders. Other times they jumped ship and made themselves at home. The cat rode the coattails of humans to the ends of the earth, and many islands in between.

  The cat’s global wanderings were to be exceeded only by the rat’s. But the speed with which the cat could ravage island faunas was exceeded by none. In the hierarchy of Oceania’s invading predators, the cat came to be classified as a superpredator. Its mouth was a butcher’s array of artery-slicing canines and meat-shearing molars, its paws concealing twenty switchblades. The weaponry was directed at times by a brain hardwired and hair-triggered for repeated attack regardless of hunger. Such was the nature of the beast behind the gruesome slaughters so commonly greeting the seabird biologist, the dead lying en masse with broken necks and missing brains and hardly a feather otherwise ruffled.

  Among grounded gatherings of nesting birds, the litany of cat carnage ran long. On the New Zealand island of Raoul, a rookery of sooty terns likely numbering hundreds of thousands when the first cats were put ashore in the 1800s was gone by the 1990s. In the Kerguelen Archipelago, a subantarctic wilderness of penguins and petrels and albatross, cats at the peak of their killing were calculated to be removing nearly one and a quarter million seabirds per year. On Ascension Island, in the middle of the Atlantic Ocean, cats delivered by European colonists would by the twentieth century drive a gathering of some twenty million seabirds to within 2 percent of annihilation, the survivors left clinging to the sheerest cliffs and offshore sea stacks.

  By the time Bill Wood arrived in Baja, feral cats of the world had extinguished at least thirty-three bird species and decimated uncounted others. And birds were only the more obvious victims. In the era of the feral cat the Mexican islands had thus far lost more than ten of their unique rodents. Distinctive forms of lizards and snakes had all grown scarce or disappeared with the coming of the cat. This was the buzzsaw of biological diversity that Wood was hired to destroy.

  For Wood the transition from Sierra Nevada bobcats to Baja house cats entailed certain adjustments, the least of which involved retooling for the new quarry. Never mind that these stray cats were animals a third the size of his specialty, demanding smaller traps, lighter trigge
rs, and more delicate placements. For Wood the ultimate challenge was maintaining his coveted independence.

  Tershy had started Wood off, handing him the latest scientific papers on the subject, prescribing orderly grids of traps, mathematically configured to cover every square inch of cat territory. Wood secretly put them aside. His tool of choice was the scalpel, not the sledgehammer. As Wood went to work, meticulously setting his traps, Tershy would sometimes follow, camera in hand, documenting every detail. Wood stifled a desire to throw Tershy and his damned camera in the ocean. He could imagine his trapping secrets, so painstakingly earned and rabidly guarded all these years, splashed on a big screen before a packed auditorium. What Wood could not imagine then was that one day the man spilling it all at the podium would be he.

  AMBASSADOR BILL

  Much as he might have wished otherwise, there were feral cats enough in Baja to defeat even the single greatest trapper in the land, and only one Bill Wood to go around. If Wood was going to finish his job, he was going to need help. And others were going to need his.

  Wood began appearing before Tershy and Croll’s Mexican counterparts like some strange sort of shaman from the North, sent to cure their curse of cats. The Mexicans were primarily shooters, hunting by night with rifles and headlamps. Few seemed particularly interested in learning Wood’s mysterious leghold weaponry. Safe enough with his secrets, he would lay the lines, setting the traps in his inimitable way, and with the help of an interpreter would instruct the others to check them. Then on to the next island he went.

  As Wood toured the islands, the purpose of it all began to sink in. The stakes in Baja figured not in the profit of bobcat pelts but in million-year lines of evolution. These were no longer fishing trips disguised as work. This was a noble cause he had stumbled into. Applying his singular skills to saving wildlife gave Wood a satisfaction he’d never known as a commercial fur trapper. “It got to where I realized I’d done a lot of damage catching and hunting things,” he would later say. “To give something back—that was important to me.”