Rat Island

by William Stolzenburg

  Warfarin acted slowly and quietly, producing no stricken seizures or terrorizing spectacles. The poisoned rat fell weak and lethargic, too far removed from its lethal bite of food to connect the dots of cause and effect. It commonly succumbed, by outward appearance, as one dying in its sleep. Neither victim nor onlookers ever knew what had hit it. And if by chance the untended dog or child happened upon stray bait, there was a ready antidote, as simple as a prescribed dose of vitamin K.

  By the 1950s warfarin had become the world’s dominant, if something less than perfect, weapon against the rat. Death by warfarin required large doses, delivered over several feedings. A big eradication campaign required heavy labor and lots of expensive man-hours. More crucial still, if the bait ran out before the rat’s luck did, the rat survived.

  And that which didn’t kill the rat made it stronger. Over time those rats surviving a warfarin attack grew immune. Within a decade of warfarin’s international deployment, rats in the United Kingdom, Denmark, the Netherlands, Germany, France, and the United States were shrugging it off. Brown rats, black rats, and house mice were proving impervious. Survivors were rapidly passing resistance to their pups. With the mutation of what amounted to a single molecule, the rats had begun turning the warfarin war in their favor. The eradicators were now facing a monster of their own design, a global phenomenon that had come to be called the superrat.

  When the international alarm was raised regarding the rise of the superrat, the young American Dale Kaukeinen was among those sent to scout it out. For his research project as a graduate student of biology, Kaukeinen traversed the country in search of superrats. In twenty out of fifty cities he visited, he found warfarin resistance. Soon thereafter the U.S. government declared quits on its backfiring warfarin campaign.

  Meanwhile the chemists in their labs had been scrambling to defeat the mutant molecule, searching for the superrat’s kryptonite. They tinkered with their formulas, cherry-picking the most virulent strains of warfarin’s anticoagulant compounds. Finally they hit upon a new mix of molecules that could invariably swamp the most resistant animal’s clotting mechanism. One of those compounds they named brodifacoum. Brodifacoum’s toxicity surpassed that of warfarin by a hundred times. A single gram would kill the biggest brown rat. With brodifacoum there would be no need for multiple doses. There would be no escapees, no wounded survivors to spread their resistance and revive the masses. It was now a matter of getting the rat to eat it.

  Kaukeinen, fresh out of grad school, was enlisted in the international team assigned the job of readying brodifacoum for the field. At a lab in North Carolina, his first task was to find the bait package that would stand up to the weather and irresistibly lure every rat. He would put out placebos, packaged in various forms and recipes, and watch through one-way mirrors and hidden television cameras. From his blind he would come to acquaint himself with an animal supremely schooled for the scientist’s little games of cat and mouse.

  He began by mixing his baits with food preservatives, for better shelf life. He added innocuous preservatives, of the kind found in every commercial loaf of bread. His rats would have none of it. He added a tiny amount of insecticide, to keep the ants and cockroaches away from his baits in the field. The rats wouldn’t eat it. They were detecting Kaukeinen’s additives in parts per billion—as one might taste a drop of chlorine mixed in a fourteen-thousand-gallon pool. Having been chased through the eons as prey for the predatory masses, the rat had developed wariness to degrees hardly fathomable to the human senses.

  But upon finding a food they approved of, Kaukeinen’s rats dove in with abandon. They would eat their fill and stash the rest, hoarding food far in excess of their appetites. Kaukeinen would dig up their burrows and find single larders stocked with twenty pounds of rat chow. It struck Kaukeinen as neither gluttony nor greed, but a shrewd survival strategy. “It’s something ingrained in them,” said Kaukeinen. “That gene to hoard. I can imagine when that probably came in pretty handy. You have a natural calamity, or human disturbance, your regular food source gets cut off. You didn’t have that nice odor trail to the dumpster anymore. But you had this big slug of food back in the home nest. So not to worry. They didn’t even have to go outside and expose themselves to danger to keep eating.”

  Then there was that infamous rat talent for evasion. Kaukeinen would occasionally notice that one of his subjects was missing from the lab (or from his shed at home, where, truth be told, he sometimes kept the enemy as pets). The escapee would disappear, and Kaukeinen would assume he’d seen the last of it. He would dutifully put out baits and traps, to no avail, and return to his business. But eventually Kaukeinen would come upon little signs—a track here, a dropping there—of a midnight visitor now watching him by day.

  Among the most admired of Kaukeinen’s subjects was the Kleenex Thief. The lab workers had begun to notice a box of tissues mysteriously emptying sometime between their departure at night and their morning return. One night Kaukeinen stayed at work and waited, looking through a one-way mirror into his lab, illuminated with a red light invisible to rodent eyes. At the appointed hour, the Kleenex Thief made his appearance. Scampering across the suspended ceiling, shimmying down an electrical conduit, scurrying across the tile floor, jumping up to a chair, and beelining across a cabinet—straight to the Kleenex box the rat proceeded, yanking out one single-ply tissue, then retracing his steps through the obstacle course, prize in mouth. This process the rat would continue to repeat in a tireless rendition of capture the flag. The Kleenex Thief, it now became clear, was no he but a maternal she, dutifully building her nest.

  Even the one supposed rat weakness, its legendary nearsightedness, Kaukeinen would find to be badly and perhaps wishfully overestimated. He kept an outdoor colony of rats, on which he regularly spied. He would watch the rats as they were watching their world. He watched as visitors approached the rats’ pen. The visitors would invariably leave believing the pen empty. Strangers would get no closer than a hundred feet before the rats would scatter. To see if the rats could be surprised, Kaukeinen had his lab technicians sneak up guerrilla-style. The rats busted them every time. Beady eyes or no, the rat had an uncanny knack for seeing its enemies coming, with good evolutionary reason. These were eyes sharpened to an acute edge by the eternal threat of death, honed to exacting detectors of motion by millions of years of foxes leaping from the grass and hawks stooping from aloft.

  Inevitably the games of hide-and-seek and play fighting would end. Kaukeinen would be forced by protocol to proceed to the final step of the experiment, adding to the innocuous baits the lethal dose of brodifacoum. He hated the death. He had come to see in his adversary a soul of admirable wits and resolve. To quiet his conscience, he reminded himself that this was a creature whose kin, the black rat, had once carried the fleas that had carried the bacterium of bubonic plague, which four centuries earlier had swept a third of humanity to horrific death. He kept in mind, as he killed, that this was the rat whose kind was even now eating a fifth of the world’s crops, adding filth to his country’s foodstuffs, biting and sometimes maiming thousands of his cities’ poverty stricken. He had seen, in his own country, homeless people and kids in cribs with toes bitten off. He was reminded daily of the rat’s ferocious potential by his own forefinger, left forever numb from one bone-penetrating strike of an incisor.

  Brodifacoum, registered in the United Kingdom in 1978 under the trade name Talon, would quickly replace warfarin as the leading weapon in the anti-rat arsenal. Back in the world of island conservation, the poison brought new hopes. Brodifacoum promised quicker death. It meant dead rats with fewer bags of heavy bait hefted into the wilderness. It raised the unthinkable possibility of eradication. Within a year of its arrival on the market, biologists were deploying brodifacoum on tiny islands off New Zealand’s coast, testing the new poison in tandem with their more familiar snap traps and other poisons.

  Among those most keenly following the developments was Rowley Taylor. He had once be
en among those accepting the party line, of the futility of fighting this formidable little animal on anything more than the tiniest offshore islands. But with brodifacoum now in the battery, the little victories beginning to amass, and a developing appreciation for the workings of rat society, the odds, to Taylor’s mind, had fundamentally shifted.

  The rat profile that Taylor had gleaned from labs like Kaukeinen’s—and the endless flood of medical and behavioral research on the brown rat’s domesticated model, the white lab rat—suggested a creature of complex social skills. The apparent chaos of wild-rat society, as inferred from the occasional glimpse of naked tails scattering before the flashlight beam, was, under closer scrutiny, a well-structured society of leaders and followers, rules and protocol.

  Rat society was dominated by big males. The basic fact of their survival to adulthood, in the notoriously fast and ephemeral life of the rat, implied a degree of savvy, a calculated balance of daring and caution, a model to be emulated. The successful rat had evolved as nature’s ultimate neophobe, a creature supremely and justifiably suspicious of novelty. Exploring new objects willy-nilly and mindlessly gobbling new foods were behaviors that characterized those seldom living to bear offspring. Mechanical traps, manufactured baits, poison pellets—all underwent careful inspection, most commonly led by the dominant males.

  Once the new food or shelter had passed the sniff test of the colony’s reigning kingpins—once they’d sated themselves and piled their larders to their greediest heights—the word went out. The message went forth on the scent of rat breath, passed like gossip in the myriad nose-to-nose meetings of the colony’s cohorts. The message was “There’s food back there, it’s good, and the king’s had his fill. Let’s go.”

  Following such protocol of rat society, Taylor sketched out his strategy. He would forgo the standard broadside in favor of the surgical attack. He would use just poison and the rats’ own intelligence network to defeat them.

  “YOU’RE CRAZY, THOMAS!”

  Taylor now needed a target; his protégé Bruce Thomas knew just the place. Thomas had been itching for a shot at clearing Breaksea Island since his rude welcome there by rats a decade before. But both knew better than to aim their first stone at Goliath.

  Thomas organized another research trip to Fiordland’s Breaksea Sound, this time with Taylor to have a look at one of the candidates, a twenty-two-acre dome of forest called Hawea Island. It so happened that on that boat sailed their boss Richard Sadlier, director of ecology for the Department of Science and Industrial Research. It soon became clear that the would-be rat busters had more than rodents in the opposing camp.

  As the three floated past Hawea, Thomas pointed and said to Sadlier, “There’s rats on there, Richard, and that’s where we should start.”

  Sadlier scoffed. “Getting rats off a forested island like that? It’s impossible. You couldn’t do it. You couldn’t get rats off a forested island like that. It’s impossible.”

  “Well, you know,” Thomas answered, “I think we could, Richard. But what do you think, Rowley?”

  The laconic Taylor stood leaning on the rail, staring at the little island, then quietly declared, “Yeah, I think we could do it.”

  Thomas then turned around, facing the looming profile of Breaksea Island, its monstrous heights wrapped in a band of mist, and dropped his bomb. “But that’s the island I really want to do.”

  Sadlier looked at Breaksea and all but jumped out of the boat. “Rats off that! Rats off that! You’re crazy, Thomas! You’re absolutely fucking crazy!”

  Thomas again turned to his mentor. “What do you think, Rowley?”

  Taylor panned the length of the island’s forbidding ruggedness, contemplated for a bit, and nodded his head. “Well, it’ll take a lot more time and money to set it up, but yes, I think we could do it.”

  In March 1986, Taylor and Thomas and a handful of volunteers landed on Hawea, for what was to be a live rehearsal for their big show on Breaksea. They set about dissecting Hawea into a crosshatch of foot trails. Every forty meters of trail they stopped to place a bait station, each amounting to a fifteen-inch length of plastic drain pipe, anchored in place by hoops of fencing wire. They allowed three weeks for the most phobic of the rats to get comfortable with these foreign objects intruding on their territories, then laid the baits. On April 10, into each of the seventy-three plastic tunnels went two wax briquettes laced with brodifacoum at five parts per thousand. Seven days later not a rat could be seen on Hawea.

  With Hawea’s rats now history, Taylor and Thomas raised their sights to the ultimate target. Breaksea, to their minds, was a simple matter of scaling up their proven technique by the proper order of magnitude. But for those sitting in the administrator chairs, clearing Hawea’s twenty-two acres was one thing; clearing Breaksea, at two hundred times the size, with forested mountains and cliffs, was another. Breaksea, the bureaucrats scoffed, would amount to nothing but a waste of personnel and money.

  Their bosses would slash their budget, but by then Taylor and Thomas had all but set sail. They had already finagled a donation from a major manufacturer of brodifacoum. They had moles in the national park system organizing supplies, a hut, and helicopter time. They had already enlisted a league of volunteers from around the world, eager to be part of conservation history. With money and manpower already in place, the department heads found themselves politically hog-tied. They would concede to the minor mutiny, but not without one parting shot over the bow.

  Taylor and Thomas, in earlier interrogations, had offhandedly estimated they could finish the job on Breaksea in about three weeks. Their rough estimate now became law: Taylor and Thomas and every last one of their troops were to evacuate Breaksea Island within twenty-one days of laying poison, rats gone or not.

  As they had on Hawea, they would first quell the rats’ anxieties and suspicions. Weeks before the first poison was laid, they laid their trails and plastic tunnels, freely inviting all comings and goings, laying a foundation of trust. By the end of April 1988, Breaksea had a bait station within sniffing distance of every rat on the island.

  On May 25 the rat team assembled once again on Breaksea for final instructions. Taylor and Thomas had a team of six volunteer rat busters, a stockpile of 770 pounds of poison, and a helicopter pilot standing by for special duty. They gathered at command central—a rustic hut with a table, some chairs, and a map hanging from the wall. The map was pierced by 744 blue pushpins marking every bait station. On the table lay a box of red pushpins. As the rats began taking baits, the blue pushpins were to be replaced by red.

  The next day the Breaksea troops headed out, shouldering sacks of bait. By the end of the day 744 stations, covering every rat territory on Breaksea plus two rocky spires offshore, contained two brodifacoum-laced briquettes of wax. There would be no place to run or swim for any rat of Breaksea.

  Word spread quickly among the rat community: The strangers have come bearing food, and it is good. On the morning of day two the first checks of the stations would find baits missing. By day three every station was being pilfered. The map at headquarters flushed from blue pins to red. By day five the baits were disappearing as fast as the troops could lay them.

  As the trap unfolded, Taylor took to hiding himself in the bushes and observing. He soon observed that the spying game worked both ways. One particular rat seemed oddly hesitant about entering the bait tunnel. Taylor sat and sat, waiting for the rat to make its move. Tiring of the game of patience Taylor looked into his lunch bag. As he looked up, the rat was exiting the tunnel with bait.

  Taylor pretended to look again into his bag, this time spying out of the corner of his eye. As he reached in, the rat darted for the bait. Taylor now knew what it was to be under the scope, with a rat dissecting his every move.

  The Breaksea eradication was going off like clockwork. The big males were laying claims to the stations, eating their fill, stocking their larders, chasing all comers, and eating again. The rats could hardly wait fo
r their next visit from the men with satchels. Taylor would walk up to a tunnel, tap it as if leaving another offering, and pretend to leave. Almost before he was out of sight, the attending rat would be in the tunnel. Taylor watched one rat making off with no less than twenty-two baits.

  Despite their eons of learned distrust, the rats had badly misjudged these strangers bearing gifts. As the poison settled into their livers, their lifeblood began to leak. As the leaders lay dying in their burrows, their unguarded territories came under siege by the next-boldest cohort. And on rolled the waves of death.

  Back at headquarters, the battle was being played out in two dimensions on the wall. As the massacre progressed, the map changed color again. Red pins, signifying baits still being stolen, began to revert back to the quiet symbol of blue, now signifying death. By day ten half the stations on the island had been vacated. The masses were falling, the rat tide had begun to ebb.

  As the deadline approached, the map tenders grew ever more busy pulling red pins, inserting the blue. On day twenty, amid a sea of blue, one lonely little red pin remained. And this, so far as Taylor and Thomas were concerned, was the last gasp of the living dead. Having already ingested a lethal dose several times over, the last rat of Breaksea was stockpiling its own grave.