A Plague on Ibiza

This article appears in VICE Magazine's Algorithms issue, which investigates the rules that govern our society, and what happens when they're broken.

Elba Montes was waiting for me in a small white Volkswagen SUV. “Should we go to my house?” she asked. At the time, Montes was an environmental project manager with the local government in Ibiza, and a biodiversity and evolutionary biology PhD student at the University of Valencia. She had a good-humored expression, and brown hair streaked with auburn dye. “There are snakes in the freezer.”

For many people living elsewhere, the word “Ibiza” might conjure images of Leonardo DiCaprio hovering above the sea on a flyboard, or British tourists falling off balconies to their deaths, or a 2018 Netflix comedy about a publicist who falls in love with a DJ. Snakes aren’t really part of the brand. But since arriving unexpectedly in the early 2000s, then fanning out like fingers gently stretching out from the island’s northeast flank, herpetofauna have become a local preoccupation.

When we met, Montes was one of the primary local researchers studying the Hemorrhois hippocrepis, or horseshoe whip snake, a medium-sized, fairly understated-looking snake with large round eyes and a horseshoe-like pattern on its head. Since the first sighting in 2003, three snake species have been introduced to Ibiza and Formentera, known as the Pityusic Islands, but the horseshoe whip snake, Montes’s subject, is now the most common in Ibiza. It’s native to southern Spain and other areas in the region, but considered invasive in Ibiza, which sits about 60 miles off the mainland coast in the southwest corner of the Balearic archipelago. Although the snakes aren’t poisonous to humans, Montes’s research suggests that they are endangering the survival of an iconic local lizard.

Though the term “invasive species” can imply some measure of intent, snakes did not simply decide to come to Ibiza, much like wasps did not ship themselves to Hawaii inside of Christmas trees, or how Canadian beavers did not paddle all the way down to Tierra del Fuego determined to plow through an old-growth forest. People brought them. The earliest government documentation of a snake in Ibiza was in the village of Sant Josep de sa Talaia, after a man sprayed water inside the trunk of an olive tree imported from Córdoba, Spain, and inadvertently caused the animal to flee.

“There was a story on the island that snakes will never survive because of the soil,” said Bernd Brosius, a retired landscaping business owner. Pliny the Elder declared something to this effect in the year 77, and the island itself, Eivissa, is believed to have been named after the ancient god Bes, who was sometimes depicted with a knife in one hand and a snake in the other (or occasionally strangling snakes with both his hands). Until 2003, no wild snakes of any species had been documented on the Pityusic islands, aside from a dwarf viper that disappeared when humans first arrived 4,000 years ago. This ominous historical context has not gone unremarked upon in scientific papers, newspaper articles and a letter from local activists scolding government officials.

“This was a story which I always believed,” Brosius continued. (Brosius was not entirely alone; a landscape architect told me that a friend occasionally takes his pet boa on trips off the island for preventative health reasons.) “And so I said oh, not a big problem, they’re going to die off. But all of a sudden I found they became more and more and more.”

Local reporting on the topic has been extensive—the Spanish newspaper El Mundo dubbed Ibiza and Formentera an “Eden for snakes”; another 2018 article featured a dead snake, several meters long, hanging off the claw of a bulldozer with its entrails hanging out. There’s even a Facebook group for English-speaking Ibiza residents called “Snakes In Ibiza No Thank You” dedicated to snake news, trapping methods, and the occasional photograph, including one of a small boy clutching a large snake vertically in one hand, his eyes wide with wonder.

Montes’s three-legged cat flounced past us as she showed me around her home, a whitewashed space with high ceilings that she shared with her landlord. She considers herself lucky to be able to afford her rent, she told me later, which, she said, is “really really really cheap compared to everything here.” She wasn’t planning to stay in Ibiza for much longer.

Until very recently, the Balearic Islands were a major tourist destination in Spain, which is the second-most visited country in the world. At the time of my visit, just before the pandemic hit, Ibiza was home to the world’s most expensive restaurant, as well as a club called Amnesia whose owner was arrested in 2016 during a money laundering raid, and a gated community for millionaires complete with a “nondenominational temple” that was built on a foundation of crushed crystals. Real estate prices have increased significantly in recent decades, a real estate agent in the luxury Mediterranean market told me in March, and “quite a few northern Europeans have chosen Ibiza as a place to live, to bring their kids, and have a healthier, more relaxed life, rather than living in the insanity of London or Paris or wherever.”

Meanwhile, according to a 2017 report on Ibiza’s socio-environmental carrying capacity, the income of an average worker has barely covered basic housing costs. In past years, some seasonal workers have had to rent balconies. The island’s economy is built around hospitality, but for workers, “it’s very hard here, the life in Ibiza,” said Milagros Carreño, a local spokesperson for Las Kellys, a national labor group representing housekeepers in the tourism sector. Carreño takes valium and anti-inflammatories every day to keep up with the workload, she said, which, when we spoke through a translator in early July, she expected to increase with coronavirus-related precautions. “Our bodies are destroyed by this work.”

Over the years, opulent gardens have bloomed in Ibiza. But because plants are living habitats, they tend to collect other creatures. When they are moved, guests often come along. A knobby old olive tree with snakes in it is an unusually biblical demonstration of this rule—“They have holes, crevices, different areas where animals can hide inside,” said Samuel Pinya, a biologist at the University of the Balearic Islands.

Researchers and government officials in the Balearic Islands believe that these olive trees—usually uprooted from their groves on the mainland and shipped as landscaping products—have likely been the main pathway for the snakes’ entry (though there’s often more than one way in, and other imports, like bales of hay, could also be contributing). The snakes, which have been seen and photographed on and around the trees, share a habitat with the region of Spain where many of the olive trees come from, and their appearance correlates with what researchers have called the “exponential” growth in the trees’ importation to the Balearic Islands. According to a 2019 report, ornamental olive trees have also introduced the common yellow scorpion to Ibiza, as well as Macrothele calpeiana, a very large European spider.

Gardening is not exclusive to the ultra-wealthy, and neither is tourism in Ibiza, which historically has been more closely associated with 20-somethings in a K-hole trawling for “hot birds.” But these particular ornamental trees—occasionally over a thousand years old—can sell for anywhere from several hundred to around 50,000 euros each, and are mostly bought by second home-owners, hotel complexes, developers, and other high-income buyers.

“If we hadn't these capricious rich people who wanted the Mediterranean garden because it's fashion, then we wouldn't have the snakes,” Montes said bluntly.

Similar to places like Hawaii and the Galapagos Islands, economic development, tourism and tourism-adjacent urban sprawl in the archipelago has been associated with an assortment of environmental pressures beyond the snakes, from water supply issues to “a continuous discharge of sewage” into the sea. “The economic system is embedded within the natural system,” said Ivan Murray, a geography lecturer at the university who co-authored the carrying capacity report.

At her house, Montes showed me a photo of a blue-ish Ibiza wall lizard intact inside the open stomach of a snake, surrounded by an unusually large layer of fat. She also took out the snakes, frozen in permanent figure-eight patterns. She had caught and killed them in her yard, and was keeping them for future study. They looked like plastic toys, slightly mangled. One was large, with dried orange-red blood on its underside and its jaw bent open in an unnatural position. Another was tiny, curled delicately into itself like a loose bowline knot.

“If they are here and they are bad for the island, it’s because of us, not because of them,” she said, the last light fading through the glass doors as we sat down at her kitchen table.

Only a small percentage of species relocated by humans end up having impacts that are considered harmful towards the health, economy or ecosystem of their new home, earning them the “invasive” category. But the total number being pinballed around the world continues to grow, and on islands in particular, where species have evolved in relatively isolated, sometimes fantastical ways, invasive species are considered a serious threat to biodiversity. Islands often lack entire groups of fauna, such as (in Ibiza’s case) snakes, making whoever evolved there potentially more vulnerable to certain newcomers. Islands also import a lot of things, leading to higher rates of species introductions. In an escalating extinction crisis, the stakes are high.

In 2016, Montes co-authored a study led by PhD student Arlo Hinckley that found that a substantial percentage of the horseshoe whip snake’s diet was composed of the speckled Ibiza wall lizard, or Podarcis pityusensis. The lizards are part of the story the island tells itself and its visitors, their friendly outline reproduced on bumper stickers, tourist tchotchkes, wooden gates and lawn ornaments. They’re the lone native reptile in Ibiza and Formentera, and as an endemic species, the sub-archipelago is their only natural range; they’re also seed dispersers, playing an important role in the island’s ecosystem. On islets surrounding Ibiza, where they have evolved in tiny isolated populations, they appear in spectacular, gemlike shades of blue and other colors.

“The lizards have been in danger because of the cats, the dogs, kestrels,” Montes said. “But this is new.” A warning lurked nearby: a few thousand years ago, an introduced snake is believed to have contributed to the extinction of a similar lizard, the Lilford’s wall lizard, from the main islands of Menorca and Mallorca.

At the time of my visit, Montes was readying a chapter of her dissertation for submission to a journal, co-authored by her advisor Juan Pleguezuelos, Brahim Chergui, an assistant professor of mathematics at the University of Hassan II Casablanca in Morocco, and Fred Kraus, an evolutionary biologist at the University of Michigan. Snakes are hard to study because they’re hard to find; researchers often have to rely on rough indicators like traps and reported sightings. But Montes performed a census in 2018 suggesting that the island’s mascot is rapidly disappearing, and that the horseshoe whip snakes are responsible: in areas determined to have high horseshoe whip snake densities, she found no lizards. She also found no lizards on an offshore islet previously observed to have them, shortly after a snake was captured swimming its way.

The study hasn’t completed peer review or been accepted for publication yet, and in past years the snake threat hasn’t been settled among researchers. “There are some people saying there is an impact, others that are saying there is not an impact,” summarized Samuel Pinya. “My opinion is that there is an impact, but up to date we cannot quantify that impact.”

But Montes is firm about the implications of her findings. “If the snakes spread throughout the island, then the lizard will be gone from the island,” she predicted.

Something similar happened in Guam, where Montes visited in 2017 to learn about the snake control mechanisms implemented there. Guam is often cited as a sort of worst-case-scenario in the field of invasion biology. In the decades after poisonous brown tree snakes arrived, probably in U.S. military cargo, six lizard species vanished, and, famously, most of the island’s native birds. In their place, the forests are filled with spiderwebs.

Though she does store their dead mangled bodies in her freezer, Montes loves horseshoe whip snakes. Her face brightened visibly when she talked about them. She even hand-painted an image of one with soulful green-flecked eyes for a PowerPoint presentation on their reproductive ecology. We watched a video of two males fighting elegantly for dominance, swiveling their heads on top of each other's without touching until one declared victory, like a mimed thumb war.

“I hate to kill them,” she muttered. Once a snake is caught, the protocol is to knock them unconscious against a hard surface and then smash them in the head with a rock or hammer.

She often dreams of snakes, she confided later. Sometimes, in the dreams, they turn into a viper and kill her, but recently they’ve been gentler, transforming into impossible technicolor versions of themselves.

“I brought in containers and containers and containers of these trees to the island,” Brosius recalled in a phone call. Researchers and nursery owners associate the ornamental olive tree trade with faster rates of tree turnover as olive oil production intensified. The trees are often uprooted and moved in the winter, when their growth has slowed—“otherwise the tree suffers,” he explained. But he hadn’t realized, he said, that inside the dormant trees were hibernating snakes.

“In the last years I told the guys, listen boys, I don’t want to bring in any more fucking snakes, please put hot water in all the olive trees so the snakes come out,” he said. (Washing the trees is one technique some sellers use before sending them to more strictly regulated destinations.)

When I visited Noah’s Garden, I spent some time gawking at one of Brosius’s olive trees, which was so large and twisted and overwhelmingly beautiful that it looked like it ought to be accompanied by a centaur. He told me that it was his male customers who really pushed to buy them: “This, for men, means power.”

The new old olive trees are common in Ibiza—there are properties on the island with dozens of them—though some clearly homegrown trees are also dotted around the island, in one case looming like elderly grandfathers in angry, splintered clusters over an ancient grave site. I spotted them at garden centers, in front of a clothing store near the port in Ibiza Town, leaning over the edge of a pristine Mediterranean garden, standing in the elegant courtyard of a renowned architectural firm on the island.

A few were visibly sick, I noticed, with hacked-off limbs or browning leaves, throwing another wrench in the impression they were clearly meant to give: that things had always been like this, and maybe always would be.

Ibiza, Montcerisier told me dreamily, has a “special earth energy,” some kind of magnetic quality, a belief also shared by travel blogs aimed at wellness tourists. I hadn’t personally experienced this magnetism, though I was momentarily trapped in Mallorca when my destination airport in Alicante burst into flames, which was weird. Mostly I just had insomnia. I kept finding dying bugs rolling around on their backs on the floor near my bed, which felt thematically a little too on-the-nose.

Montcerisier observed that Ibiza is “getting a little bit more glamour, a little bit more like Saint Tropez.” Over the years, many people came to invest in large homes, he said, and they want high quality landscapes, though he tries to steer his clients away from thirsty tropical plants and toward native species. With increasing volumes of plant imports, Montcerisier explained, came others. “We imported the beetle, we imported the snakes, we imported the bacteria.”

Globally, the horticultural industry is hugely varied, ranging from beloved local shops running on thin margins and native plant nurseries that work on ecological restoration projects to breeders, seed companies, giant multinational corporations and online marketplaces. But its impacts can be enormous—rhododendrons planted at a resort, for example, are believed to have introduced an oomycete called Phytophthora ramorum, which has killed millions of oak and tanoak trees on the West Coast, to the Big Sur area.

“Ultimately it comes down to, well maybe we shouldn’t be moving plants at all, which is probably a non-starter,” remarked Dave Rizzo, chair of the department of plant pathology at UC Davis.

The bacteria mentioned by Montcerisier—a pathogen called Xylella fastidiosa that’s considered invasive—has killed millions of olive trees in Italy, and is also in the Balearic Islands, choking off the trees’ water supply and turning their silvery-green leaves to a crunchy rust. The beetle, called the red palm weevil, eats the hearts of (also imported) Phoenix canariensis palm trees so vigorously that you can sometimes hear them chewing.

The palm looks perfect, Montcerisier recalled. “And then from one day to another, black. Ciao.”

However, as Pickett and Richard Ostfeld warned a few years later, “the flux in the natural world has severe limits.”

In 1560, as Alfred Crosby wrote in The Columbian Exchange, the olive tree was first introduced into what had recently become Lima, Peru by a man named Antonio de Rivera. He brought seedlings back from Spain, guarding them with slaves, at about the same time that the Inca people of the region were being killed in devastating numbers by Spanish diseases. Today the trees, known as Parque El Olivar, are “practically drowning” thanks to 25 acres of imported crabgrass installed around the grove.

During the period of European colonial expansion, white settlers inflicted themselves and their menageries on new places all over the world, with vast ecological legacies still chomping around today. In New Zealand, “invasive species are just another form of colonization,” said Amanda Black, a research scientist and co-founder of the Māori Biosecurity Network, or Te Tira Whakamātaki. With industrialization, globalization and the expansion of consumer capitalism, the pace and spread of species translocations kept ratcheting up all over the world, and Europe increasingly got a taste of its own medicine.

Today, research has homed in on the human activities behind these movements. The plant trade plays a role, as does ballast water on ships, the exotic pet trade, tourism, cargo containers, the U.S. military, even the billions of tons of plastics in the ocean now apparently serving as highly durable rafts. People have shuffled other creatures around for lots of reasons—including as ill-advised biocontrol agents for other invasive species—but researchers have found that the number of introduced species often correlates with economic growth (though invasive species are also studied more in wealthy countries).

Ultimately, governing bodies are responsible for imposing regulations, and Montes’s latest paper includes suggestions, like quarantines, to prevent olive trees from bringing snakes into the Balearic Islands—which still hasn’t been done, frustrating Montes and local environmental activists, who have pushed hard for regulatory changes. Balearic government officials have argued that European trade laws make it difficult to regulate certain importations within the bloc.

“She’s always saying we are not doing all we should do to fight against the snakes in Ibiza,” Ivan Ramos, the head of the Species Protection Service for the Balearic government, said of Montes. “But we don’t agree with her, because most of our money is used to fight against invasive species and especially against the snakes in Ibiza.” Government traps have captured 2,700 snakes in Ibiza since 2016; using funds from the Balearic Islands’ “Sustainable Tourism Tax,” they’re increasing the number of snake traps and personnel on the island in an effort to better control the population. This year, Ramos told me, they hope to hire a team of lawyers to develop laws regulating the olive tree trade with the peninsula.

No one really expects to stop the transport of species entirely, to be clear. The idea is generally to slow the pace.

“Look at what’s going on with COVID testing,” explained Dave Rizzo. “You’ve got a shipment of a million plants, you can’t test every single one, inevitably something is going to go through.”

“We are always late,” he said at a coffee shop in Ibiza Town, speaking through my translator, a shy vegan teenager with long talon nails and a septum piercing. “Because when they arrive, we are already late.”

Colomar is a veterinarian by training, but his job mostly involves coordinating strategies for eliminating animals across the Balearic Islands, including charismatic or culturally valued species. A recent attempt to remove the goats that were eroding and destroying the endemic vegetation on es Vedra—a famous islet off Ibiza’s coast plagued by persistent rumors of UFO sightings—was placed on pause after a lawsuit, he told me. The goat population has begun to recover, and Colomar said his team will likely have to shoot more goats than originally anticipated to finish the job.

He doesn’t have a problem with goats, or snakes, or cats, he said, as we drove up one of the island’s main roadways, on our way to look at snake traps. “I have a problem with irresponsible people.” He became a bit heated, letting out a “pfft” noise that in Spain seems to mean everything is so stupid, no? Oh well. He mentioned, with disdain, that people in Madrid began buying racoons as pets after watching Pocahontas. Now they’re everywhere, and some of them have rabies.

We arrived at our destination, a flat clearing backed by forest that looked out past shrubland onto low green hills leading out to the sea. Scores of ornamental olive trees had been planted at an enormous villa rental nearby, he said, which he believes initiated the snake population in this area. Several meters away from one of the simple wooden snake traps was a low stone wall. The snakes and lizards share a habitat, and inside this wall, he said, both were hibernating.

“Formerly, all of these forests were transformed into farmlands, because people were very hungry,” Colomar said. A degree of human disturbance has favored the Ibiza wall lizards—they like the open spaces and rock walls that crisscross the island’s landscape. But as the island abandoned farming, he said, the forests began to recover ground.

Montes’s research suggests that other factors, including forest regrowth, can’t explain the dramatic changes she observed. Colomar agrees with Montes that the snakes—particularly the horseshoe whip snakes—threaten the Ibiza wall lizards, and he believes that without them, the lizard populations would cling on. But the lizards, Colomar emphasized, have been under additional pressures, like cats, pesticides, and land use change.

When I was back in the U.S., I asked Katharine Suding, a plant community ecologist at the University of Colorado at Boulder, how introduced species tend to fit into this constellation of human impacts.

“Restoration ecology often thinks about these threats as simultaneous,” she replied. “And that if the system is impacted by a lot of human disturbances, that system is going to be much more susceptible to exotic species coming in, which then will change it even more, and you’ll start kind of tumbling down this hill.”

“I don’t have to kill genets,” he said. “Nature has already changed, I can't do anything. We can’t go back to the prehistoric era. We exist in the current world.”

Species translocations are a complex and context-dependent process, and the categories that frame the field of invasion science are often contentious. Some have argued, controversially, that a species’ origin shouldn’t matter, or that invasive species are more benign than advertised, or that the field itself shouldn’t exist, and some scientists have responded with heated declarations of “invasive species denialism.”

Folded in are ongoing calls of xenophobia, as critics have compared conservation efforts to keep nonhumans in their imagined-to-be-natural place with racist and nationalist anxieties around human migration. As Smithsonian has reported, terms like “alien” and “invasion” certainly are the same ones that Trump and other white nationalists use to demonize immigrants and refugees, and particularly in a time of rising ecofascism—and regular fascism—it can be hard to hear them as neutral, regardless of scientists’ intent. Of course, geopolitical borders often don’t even sync up with nonhuman communities. The snakes causing problems in Ibiza are from Spain, and the olive trees are a commodified expression of Balearic heritage.

Complications are everywhere. As scientists regularly note, the “negative” impacts that generally define a species as invasive are subjective, to varying degrees (and not everyone uses impacts to define what’s “invasive”). One team of researchers recently went so far as to suggest that Pablo Escobar’s “cocaine hippos” are stepping into ecosystem roles lost during the late Pleistocene. Climate change adds its own twists, further complicating origin labels (or, some have argued, dismantling the native/non-native binary entirely).

Some animals who are threatened by invasive species in one place might even face eradication attempts in another. The Ibiza wall lizards, though technically endemic to the Pityusic Islands, are also considered invasive on the Basque islet of San Juan de Gaztelugatxe, a former Game of Thrones set. What then?

It’s easy to fall down a whirlpool here. But for many, like Julissa Rojas-Sandoval, a researcher at the University of Connecticut who studies invasive plants in the Caribbean, inaction is unacceptable. “If the species is impacting native species or unique species that you have in the area, you need to do something,” she told me. “The point is that we are the ones who are moving these species.”

Back at the trapping site, we returned to Colomar’s car and drove down the hill. I strained to glimpse the viIla’s olive trees through a surrounding fence, and asked if he’d contacted the owners.

“They haven’t done anything illegal. What can I say? ‘I don’t like what you have done’?” Colomar laughed. “They’re not the only ones.”

Martin Cristóbal Torres, a gardener, belongs to the anarcho-syndicalist union CGT, which he told me has helped feed dozens of struggling families. In Ibiza, as everywhere, the pandemic is exacerbating existing inequities and injustices. In general, “it takes a lot more work to convince someone to hire a Senegalese person than a Spanish person,” said Ndiaga Sarr, president of the Senegalese Association of Ibiza and Formentera, speaking in French. Now, he said, though a limited tourism reopening has begun, jobs are even more scarce.

Celebrities and the ultra-rich, the BBC reported, have been enjoying the quiet. A recent report by a real estate company specializing in luxury properties noted that inquiries have increased since the onset of the pandemic.

The coronavirus, which some researchers have been comparing to an invasive species, has demonstrated the extent to which humans are suspended within ecological systems, and, as Ferris Jabr wrote in the New York Times Magazine, the extent to which humans have unilaterally re-shaped and harmed those systems.

“The chytrid fungus that attacks amphibians worldwide is the main cause of global amphibian decline,” Franz Essl, an ecologist at the University of Vienna, told me. “It’s also a pandemic, but a pandemic of amphibians, caused by a pathogen that has been transported all over the world by humans.”

Human circumstances on the island may have shifted considerably, but the snakes seem to be doing more or less the same. They’ve now been detected essentially throughout Ibiza, indicating to Montes, who recently moved to Valencia, that the lizards’ days may be numbered. A homeowner recently sent the new owner of Noah’s Garden a video of a big snake on her patio. There were others, too—“they were mating in the sun,” he reported glumly.

One day soon before leaving the island, I marched up a quiet country road past a cluster of tastefully restored fincas. I’d been there for over a week, but I still hadn’t found my subjects in the wild. Surrounded by a curtain of golden-green brush, I scanned pointlessly for snakes, lizards, anything alive, although I knew they were hibernating.

In the end, it felt right that I never actually saw either. People are always in the way. Some of us more than others.

Follow Ellie Shechet on Twitter.