The Last of Its Kind

The biologist David Sischo has a tragic assignment: keeping vigil over a species’ sole survivor, then marking its extinction in real time.

John Cuneo

Sometime on New Year’s Day, as the people of Hawaii recovered from a night of revelry, in a trailer on the outskirts of Kailua, Oahu, a 14-year-old snail named George died. David Sischo, who works in the trailer but was taking a rare day off, found out at 7 o’clock the next morning, when a colleague discovered George’s limp body and texted him. “I usually don’t hear from her that early, so before I even read the text, I felt that something bad had happened,” Sischo told me.

Few people would mourn a snail, but Sischo and his team had spent years caring for George. He was a daily constant, a familiar friend. He was also the last known snail of his kind, the final Achatinella apexfulva. It is said that everyone dies alone, but that was doubly true for George—alone at the end both in his cage and in the world.

When the last of a species disappears, it usually does so unnoticed, somewhere in the wild. Only later, when repeated searches come up empty, will researchers reluctantly acknowledge that the species must be extinct. But in rare cases like George’s, when people are caring for an animal’s last known representative, extinction—an often abstract concept—becomes painfully concrete. It happens on their watch, in real time. It leaves behind a body. When Sischo rang in the new year, Achatinella apexfulva existed. A day later, it did not. “It is happening right in front of our eyes,” he said.

Hawaii was once known for its snails, or kāhuli. Most are smaller than the average garden snail, and far more beautiful. Their shells swirl with the palette of a chocolate box—dark brown, chestnut, white, the occasional splash of mint. Sischo compares them not only to candy but also, because many live in trees, to Christmas ornaments. All of them descended from ancestral mollusks that arrived in Hawaii millions of years ago, perhaps on the bodies of birds. Those stowaways gave rise to more than 750 species—an incredible radiation that turned the snails into exemplars of evolution’s generative prowess.

But in recent decades, kāhuli have come to exemplify the opposite force: extinction. Confined to specific valleys, slow to breed, and inexperienced with predators, they are uniquely vulnerable to the carnivores that have been introduced to Hawaii. Rats and chameleons are serious threats, but their archnemesis is another snail—Euglandina rosea, the aptly named rosy wolf snail. Voracious and fast (for a snail), it tracks its indigenous cousins by following their slime trails, then yanks them from their shells with a serrated tongue or swallows them, shell and all.

Sischo and his five colleagues have been trying to save native snails since 2012, when they expanded a program begun by the University of Hawaii in the 1980s and now run by the state government. In March, when I visited the 44-foot green trailer where they work, Sischo walked me to the back, where dozens of plastic cages are stacked in glass-fronted cabinets the size of refrigerators. He pointed to six cages with purple lids: “These are holding the world population of Achatinella fuscobasis.” Then he gestured to all the cabinets: “This area has 35 species in it.” Each one is already extinct in the wild, or about to be.

Snails may seem low-maintenance, but caring for them is surprisingly hard. Sprinklers regularly mist them to mimic their former forest homes, and the cabinets carefully regulate temperature and humidity. If either variable dips too low, or if the cabinets lose power, Sischo gets barraged by automatic emails and texts. He never silences his phone, even when he sleeps. When he gets alerts at odd hours, his stomach aches.

Sischo is 35, lean, and, despite his work, relentlessly chipper. When he talks about the snails, he is usually stifling laughter that is four parts gallows humor and one part panic. But the panicked portion has been growing. For some reason, already declining snail populations have recently gone into a terminal nosedive. In 2014, for example, Sischo’s team observed a species that hadn’t been seen since the 1980s—seven individuals, in a single tree. It was a hopeful event, but with the trailer still under construction, the team had nowhere to put these survivors. When the conservationists finally returned to rescue the group two years later, they were all gone. “We clipped every freaking leaf on that tree, and nothing,” Sischo said. “That will probably haunt me for the rest of my life.”

The experience, and others like it, have recalibrated his sense of urgency. Team members have repeatedly gone to check on species that they thought were stable, and ended up evacuating the remaining handful of survivors—or finding none at all. As Hawaii empties, their cabinets fill. They are running out of space, and the snails are running out of time. Without intervention, Sischo expects that 100 species will disappear in the next decade. “I think everyone, when they hear about something going extinct, thinks that there’s time,” he says. “But we’re the last people who can do anything about this.”

When animals die out, the last survivor is called an endling. It is a word of soft beauty, heartbreaking solitude, and chilling finality. The title was borne by Lonesome George, the last Pinta Island tortoise, after which George the snail was named. It unites Martha the passenger pigeon, Benjamin the thylacine, and Booming Ben the heath hen. It will eventually describe either Najin or Fatu, the two last northern white rhinos—both female, neither pregnant.

Endlings are avatars of loss. In the midst of Earth’s sixth mass extinction, these singular creatures embody the crisis facing our dwindling fauna—and our failure to avert it. By the time a species is down to its endling, it is functionally extinct. Caring for an endling can nonetheless serve as a final act of defiance, or perhaps contrition. Small wonder that the custodians of endlings often get very attached to them.

Take Mark Mandica, the executive director of the Amphibian Foundation, who cared for the last known Rabbs’ fringe-limbed tree frog—a new species that was eradicated from the wild before it even had a scientific name. In 2005, conservationists rescued dozens of Panamanian frogs from the path of a rapidly spreading killer fungus, as if pulling valuables from a burning building. Those evacuees included several Rabbs’ fringe-limbed tree frogs, some of whom made their way to the Atlanta Botanical Garden, where Mandica would later care for them. They were housed in a repurposed shipping container affectionately called the frog pod, though no one knew how to care for the species, let alone breed it.

By 2012, only one remained: a reddish-brown male whose disproportionately large eyes and feet gave him a childlike quality. Mandica’s 2-year-old son christened him Toughie, and the frog pod became a hospice. The species would go extinct, and all Mandica could do was keep its last member comfortable, clean, and fed. “It was only a matter of time before I came in and found him dead,” he told me. “That was nauseating. This species loves to hide, and when I couldn’t find him immediately, I would feel a pit in my stomach.”

Toughie was the silent type, but in 2014—after he’d spent years in captivity—Mandica finally heard him calling. He sneaked up and made a recording. “There was something about hearing him sing out that really affected me,” he says. “He was calling for a mate, and there wasn’t a mate for him on the entire planet.” Toughie died two years later, and with that, his species was extinct.

I asked Mandica whether he ever plays Toughie’s song. “I do. It’s hard not to miss him. I have lots of pictures. But there’s something about hearing him,” he told me, through tears.

Global trade networks spread the fungus that wiped out Toughie’s species and many other amphibians. Hawaii’s Department of Agriculture deliberately introduced Euglandina rosea to the islands in an ill-advised bid to control another, previously introduced snail. By shuffling nature, the forces of colonization and globalization have repeatedly wreaked havoc on indigenous ecosystems.

When Sischo finished showing me around the trailer, he took me on an hour-long drive to the northwest corner of Oahu, to check on one of the few remaining wild strongholds for kāhuli. As we traveled, I came to realize that almost everything around us had been introduced to Hawaii from elsewhere: the cardinals and mourning doves flitting through the trees, the mongoose scurrying in front of the car. As we stopped to open a gate, Sischo pointed out Cook pines from the Cook Islands, Christmas berry from South America, and eucalyptus from Australia—a “shit show of weeds,” he said.

To find native animals, we had to hike a serpentine trail to a high clearing, where a small patch of thickly grown forest is surrounded by two concentric walls. After using ladders to hop over them, Sischo walked to the closest tree, lifted a few leaves, and found a snail. Mocha brown with a thick white spiral, it looked like an elaborately carved coconut—but thumbnail-size. In 10 yards, Sischo found five more without trying. Even my untrained eyes spotted a couple. We found two adults snuggled up; the snails are, Sischo told me, surprisingly sociable. We found babies, and he lit up.

This particular species—Achatinella mustelina—was originally widespread, but now, at least in the forest reserve we were visiting, lives only in this spot. The inner wall, erected in the 1990s, successfully protected a small population from marauding predators, and today there are 300 or so. But the wall is corroded and fragile, so a better one is being built around it. Chameleons can’t scale the new wall’s smooth green sides. Rats can’t burrow under its foundation. And if E. rosea somehow manages to negotiate its lip, traverse a spiky copper mesh, and reach the top, it gets electrocuted.

That doesn’t stop it from trying. Along just one face of the wall, Sischo’s colleague Charlton Kupa’a Hee found seven E. rosea, all trapped while trying to storm the castle. They were faintly monstrous, with long eyestalks and grappling-hook-like projections on their heads. The team would normally crush them with extreme prejudice, but these seven were placed in a plastic tub for anti–E. rosea research. Immediately, a pair started mating. The species’ frantic reproduction and voracious appetite allows it to rapidly convert snail havens into ghost towns of empty shells. “It’s not their fault,” Sischo said. Then, through gritted teeth: “But I hate them.”

E. rosea is now so widespread that “exclosures” like the one we visited are among the few wild places where native snails can thrive. The team has already reintroduced into exclosures three species that were previously extinct in the wild. Every time, Sischo plays “Born Free” on his phone. “It’s a happy time, but it feels like a drop in a bucket,” he says.

At other moments, the exclosures can recall a postapocalyptic horror movie—a band of survivors holed up in a fortress, with monsters pounding on the walls. In scale, they’re not so different from the trailer: I could jog around this one’s outer wall in a minute. Instagrammers have been known to sneak inside to take selfies with the snails, occasionally breaking the barriers in the process. “What kind of existence is this?” Sischo asked.

He didn’t plan on this life. He started out as a geneticist, studying at the University of Hawaii with Michael Hadfield, whose research helped establish the snail program. But then he became the program’s coordinator—a mantle he seems likely to bear for quite some time. Hawaii’s snails are long-lived, and slow to mature and breed. “It’s like working with a rhino,” he said. “It’s a decades-long commitment to get them established.” I asked whether that means he’s in his role for good. He didn’t answer.

Back in the trailer after our visit to the exclosure, Lindsay Renshaw, the lab manager, was refreshing the snails’ accommodations—an ongoing ritual that takes days of careful work. She removed rotting vegetation and scoured every leaf for snails, which she put in a petri dish. When I arrived, she had found a dozen of them—a third of the world’s population of Achatinella bulimoides. One made a break for it, crawling over the edge of the dish with a baby stuck to its shell. Renshaw lifted it up with a leaf and put it back. Once every individual was accounted for, she cleaned the cage, packed in new foliage, and returned the snails. The work was meditative, but the responsibility, she said, was like “a heavy weight sitting on you.”

The trailer feels acutely vulnerable. It’s designed to deter would-be thieves, and to resist hurricanes. But a fire could easily destroy it, or a disease could sweep through it. Last September, a mystery pathogen appears to have entered the trailer on leaves fed to the snails, but it killed individuals from only the most numerous species. As harrowing as the episode was, there’s no good way to insure against future catastrophe. The snails can’t simply be spread among zoos or other facilities; they need dedicated equipment, experienced handlers, and a diet of native Hawaiian plants.

Consequently, it can be hard for the snails’ minders to relax, even when they are outside the trailer. How do you switch off, when your decisions mean existence or extinction? “It’s funny to think about species going extinct and then to hear news about the most ridiculous things like celebrity gossip,” Kupa’a Hee said. For him, action lightens the burden: “At least we’re aware of it and can do something.” And yet, with animals whose natural history is largely unknown, that something can be treacherous. “If you do it wrong, the snails die,” Sischo said. Deceased snails go in a cupboard morbidly labeled death cabinet. George’s remains now sit there, in their own vial.

There have been successes, too. In 2013, the team realized that Achatinella fulgens existed only in a small stand of trees. This was before the trailer was ready, so to protect the snails from E. rosea, the researchers smeared the trunks with salt and what Sischo described as an awkward amount of Vaseline. It worked—until a landslide swept most of the trees away. They scoured the wreckage and found six survivors. Today, more than 40 live in the trailer. “I think we’re on a very good trajectory,” Sischo said. “In five years, they could go back out into the wild.”

Snails are neither intelligent nor charismatic nor beloved. Sischo’s friends sometimes tease him about being “the weird snail guy”; strangers ask why he cares. He tells them that the snails recycle nutrients in the forest, and feature heavily in Hawaii’s traditional stories and songs. These points rarely convince people, but he insists that if he can just get them in the trailer, they will understand why the kāhuli are worth saving. “People melt,” he said. “When you show them that the entire population is in this chamber, it hits them.”

The cabinets are indeed inescapably poignant, though there was little to see in them when I visited. Snails are nocturnal, so by day, only a few are visible on the sides of the cages. After sunset, I have been told, it’s a different story. The cabinets bustle with activity as kāhuli swarm around their cramped ark, oozing and grazing, while several miles away, David Sischo sleeps restlessly.