In Barcelona, where wild boar are jostling tourists and raiding rubbish bins, the fightback has begun.
Collserola Natural Park looms over Barcelona, rising to about 500 metres at the Tibidabo peak. This forested ridge effectively walls off the city’s growth. Collserola is rich with wildlife, home to more than 190 animal species.
Overlooking a city of more than 1.5 million residents, which welcomes tens of millions of tourists each year, it has become a battlefront between humans and nature.
On many a hot Catalan night, wild boar from Collserola, alone or in gangs, descend on the city and mingle with the human population carousing after hours.
The encounters between Barcelonan and beast are numerous, peaking in 2016 when police logged 1,187 phone calls about nuisance boars on the loose – wild hogs rooting up turf, munching trash, attacking dogs, plundering cat-feeders, holding up traffic and running into cars.
For the past decade, Barcelona has been desperately searching for a way to keep the boar from colonising the leafy neighbourhoods – some home to footballers, bankers and celebrities – that back up against Collserola.
The low point came in 2013 when a policeman shot at a boar with his service revolver, but hit and maimed his partner instead.
Listed on the World Conservation Union’s most invasive species list, the wild boar does well in just about any environment, from semi-arid plains to alpine forests and marshy grasslands.
But more and more, they are drawn to city life. In Barcelona and Berlin, Houston and Hong Kong, groups of wild boar have been seen roaming around town at all hours.
In Rome, where I live, boars rooting through uncollected piles of trash have come to symbolise the decline of the city.
The arrival of wild boar in town squares and city parks is forcing us to confront a new reality: we are bumping up against the limits of urbanisation. This is a crisis we have largely inflicted on ourselves.
City sprawl is driving the species out of its dwindling natural habitats and forcing it to live alongside us. At the same time, we entice it with the tides of garbage and wasted food that wash around our cities.
For years, boar have been fattening up on our crops
And now they follow us into our dirty, sprawling cities. Although their numbers are increasing as they migrate to the cities, the move is making them – and us – sick.
Boars carry a host of diseases, including tuberculosis, hepatitis E and influenza A, that can make the jump to humans.
In addition to spreading disease, wild boar each year cause thousands of road accidents. In January, a group of wild boar crossed a highway south of Milan, leading to a three-car pile-up which killed one driver and injured several more.
The boar destroy property, devour ground-nesting animals – including endangered turtles’ eggs – and crops, such as fragile vine roots and shoots. Italian farmers estimate the boar inflict €100m (£90m) worth of crop damage annually. As the animals’ toll on public health and the economy climbs, communities from Texas to New South Wales have begun to wage war on the species – a campaign fought in public parks, on golf courses, on farmland and on street corners at dusk.
It was in 2014, when this species seriously threatened the global pork industry, that the boar’s presence went from nuisance to existential threat. Boars can carry African swine fever (ASF), an incurable and highly contagious virus.
Known as “pig ebola”, it kills wild and domestic pigs, creating an animal health crisis that is rapidly becoming a geopolitical one. To save the bacon from ASF, countries have been erecting physical borders with neighbours, threatening embargos, incinerating millions of farmyard pigs and offering bounties for the culling of wild boar.
A European consortium of wildlife experts, conservationists and healthcare experts, Enetwild, has, since 2017, been tasked with leading research into the link between wild boar and ASF. “The wild boar problem has been progressing for decades,” says Joaquín Vicente Baños, a Spanish scientist and coordinator of Enetwild. “It’s just that now we are seeing the consequences.”
Wild boar now number more than 10m in the EU, the group says. “Conflicts between humans and wild boar will increase,” says Baños. The numbers are putting more pressure on cities to manage the population of a pest that’s bigger than a rat, with behaviours more complex than a pigeon or stray cat.
Boar eradication strategies have been trialled, including contraception, poison and selective culling. In Berlin, the city pays a team of stadtjäger, or trained street hunters, to pick off nuisance wild boar within city limits.
They have shot thousands, but there are still roughly 3,000 in the German capital, populating the city’s green outlying enclaves and parks and venturing on to streets at night, according to the German hunting lobby.
In rural Texas, they use helicopters to flush the wild hogs into the open
A marksman, flying shotgun, picks them off one by one. “It’s expensive on a per-hour basis,” says Michael J Bodenchuk, a wildlife biologist and director of Texas Wildlife Services, a division of the US Department of Agriculture, who often does the shooting.
“But cheap on a per-pig basis. Because we’ve got so many pigs!” The only thing to put a crimp in his kill rate was the recent federal government shutdown. “We lost a month of flying,” said Bodenchuk, which put them behind their kill targets.
Barcelona takes a different approach. Shortly after the calamitous 2013 police shooting, the city hired a team of veterinary scientists from the Autonomous University of Barcelona (UAB).
The vets practise a form of wildlife management on the streets of one of Europe’s most densely-populated cities.
Their duties involve pre-planned kills – targeting females in their prime reproductive years and their young, rather than adult males – they also accompany police on late-night calls in case they are needed to euthanise a boar.
During the day, they conduct citizen outreach efforts and supply data and reports to city officials about waste management and where the city is falling behind on trimming vegetation along roads, parks and squares.
The effect of this partnership is that boar-human clashes in Barcelona have fallen by more than half, results that are gaining attention across Europe. “They’re doing great stuff,” Sebastian Vetter at the Research Institute of Wildlife Ecology in Vienna, told me.
But while scientists and conservationists see real promise in the Barcelona programme, politics and public opinion might just sink it.
Brussels last year rejected a UAB-led funding request that, the team hoped, would lead to an EU-wide plan to manage the urban boar problem along the lines of the Barcelona model. Jorge Ramón López Olvera, the UAB vet scientist managing the programme, told me his contract with Barcelona, which expires in 18 months, hinges on the whims of city hall.
Urban boar are a new urban issue, Olvera says, one that is confounding and dividing city dwellers. Homeowners want them off their street. Animal rights activists want them relocated in a humane way.
Hunters prefer the status quo, while politicians just want the problem to go away
And they don’t all agree on whether Olvera’s methods are best for Barcelona. After six years on the job, Olvera has learned that what to do about the boar has become an emotionally charged question. “It’s a human-to-human conflict as much as a human-to-wildlife one,” he says.
One evening in late May, Olvera picked me up in a beat-up Dacia Logan station wagon with a blowgun in the back and enough drugs to knock out a charging elephant. We drove to Llars Mundet on the periphery of Collserola.
Within its 14 wooded hectares there are public-housing projects, a sports complex, a senior-care home, a primary school and the Universitat de Barcelona campus, where residents and staff endure frequent unwelcome visits from families of wild boar.
City hall, the local council and Olvera’s team had scheduled for that evening a “proactive capture”, one of eight planned for hotspots throughout the summer months.
We came across a white van parked in a clearing. It belonged to Estrateko, a local animal control firm that works with Olvera’s team. A few metres beyond, suspended above the ground, was a drop-net trap that Estrateko had set up, and a circle of corn feed strategically placed below the netting.
They had rigged the trap with a wifi-enabled trigger. All the boar action – if there were any – could be viewed on a private app from a smartphone or tablet.
Swipe right on the app and a signal would trigger the release of the trap’s central spring, dropping the 10-by-10-metre net on the ground, ensnaring any animals below. The plan was to catch two boar families after dark.
I took a seat in the front of the van, with Enric Vila from Estrateko and a scientist, the Catalan naturalist Jordi Baucells Colomer. These catch-and-kill stakeouts are scheduled at night when there are more boar than people about.
I had never been on a trapping expedition before, so I didn’t know what to expect. But when I spied a cyclist, then a jogger and then dog-walkers from my vantage point in the van, the whole hunting vibe vanished. Then I noticed we were parked right next to the trap.
I figured this would be a long night.
Just then Vila pointed. “Senglar!” (Catalan for boar), he whispered excitedly. Two sturdy females and eight striped piglets were directly in front of us. A lone female tentatively approached the bait.
The others hung back. Vila predicted they wouldn’t go for it. Sure enough, they all trotted off. A few minutes later, however, an even larger group arrived. Vila and Colomer had expected them, but not quite so soon.
And then something surprising happened: a third group, unknown to my fellow van passengers, showed up. A confrontation between the two groups – more than 20 boars in all – broke out.
The original group protected its turf, chasing off the newcomers. This was not going to plan. “It’s getting too hot,” Colomer said. We high-tailed it out of there, joining Olvera and the others a safe distance from the trap.
Olvera and his colleagues are not exterminators. There is no “Boar Busters” logo on the side of the Dacia.
The car is property of UAB where, as a professor of veterinary science, Olvera teaches undergraduates and is part of the department’s wildlife ecology and health group. The unit outsources its expertise to municipalities and local firms.
Olvera’s other research projects take him out of town, to study mainly chamois in the Pyrenees and Iberian ibex – ungulates, like the wild boar. His boar work is more complex, if only because there are so many humans to contend with.
Planning meetings with alarmed business and property owners can get animated, as can gatherings with hunters who don’t always care for hunting tips from “the university guys”.
Animal rights activists would like nothing more than to shut the boar-catching operation down. Olvera’s philosophy is to keep a low profile: “We don’t want to call attention to ourselves.”
But it is clear Olvera, a native Barcelonan with a cyclist’s build and a near endless reserve of energy, likes to talk about boar. He shares with me tales of the more than 300 emergency calls they have responded to in the past six years.
There was the time a frisky male descended into the heart of the city, appearing in Plaza Catalunya just as the clubs shut for the night. Carles Conejero Fuentes, the youngest member of Olvera’s team at 28, took care of that situation. (The clubbers, mostly inebriated, failed to notice the 49kg animal in their midst, Fuentes said.) Gregorio Mentaberre, Olvera’s friend and colleague for 20 years, had a close call when one charged him in an alley.
He leapt out of its path and felt the animal graze his leg, before recovering enough to take aim with his blow-dart.
Olvera, 43, seems to get the trickiest calls, including when police, in the small hours of the morning, had to shut down a major roadway outside the CosmoCaixa science museum because a group repeatedly zipped across a grassy central reservation into east- and west-bound traffic.
Olvera had trouble with one particular boar that he couldn’t get out of the road.
He and an officer approached it in the Dacia at low speed. The officer grabbed hold of the steering wheel as Olvera leaned out the window, steadied the blow pipe and forced from his lungs a burst of air. The tranquilliser dart sank into the boar’s fleshy backside.
Once the boars are incapacitated, blood tests are taken. They are then euthanised on the spot. Autopsies are performed the next day in a lab at UAB. Blood tests indicate the overall health of the boar population and whether they pose a risk to the public.
Olvera views the city as a giant laboratory, and the boar an indicator of Barcelona’s ecological health. He is collaborating with Jordi Serra Cobo, a Spanish biologist famous for his work on how viruses make the leap from animals to humans.
The two were introduced by an official in city hall. They want to know how many urban boar carry hepatitis E, and what that means to humans. In the blood tests of city-caught boar, they see worrying seasonal up-ticks; 44% carried hepatitis E this spring.
Olvera calls the work a potential early warning system for the city. “Wild boars are pissing and defecating in city parks where children play. If children can get sick, we want to know before it becomes a problem,” he says.
The boar management plan relies heavily on the data they collect on population size and migration patterns.
A major objective is to identify the “boar corridors” – feeder roads and paths into town – and halt their movements from Collserola, their natural habitat, to the bustling city streets below.
They can now predict where the boar are likely to appear next during the May-to-September high season. They build heat maps by gauging numerous factors including rainfall, temperature levels (hot, dry conditions tend to send adults on a quest into the city for shade, food and water) and matching that with police phone logs of citizen boar sightings.
“If we know where the wild boar hot spots are,” Olvera explained. “we can plan our captures where we believe it will have the biggest impact”.
It is not enough to track and trap boar where the city meets nature. Since 2013, the UAB team has been on the street almost daily.
They are on call round the clock
They also work closely with city officials to make rubbish bins and park entrances boar-tight.
They run an education campaign, visiting school children and talking to park-goers to explain the need to keep food waste contained, and to keep a safe distance should they encounter, say, an unpredictable sow with her cute piglets in tow (no selfies!).
Last year, boar pest calls fell to 480 – a 60% drop from 2016. Olvera is cautiously optimistic the situation is coming under control. “We are effectively chasing them back into the forest now,” he says.
Across much of the world, the wild boar population has exploded since the 1980s, coinciding with the arrival of warmer winters, the improved crop yields of industrialised farming and the declining number of predators, including hunters. (Hunters grumble that millennials and property developers are killing their sport.)
The boar’s adaptability and high intelligence make them one of the most prolific large mammals on Earth.
“The wild hog,” observed The New Yorker writer Ian Frazier, “is an infestation machine.”
Young sows can produce as many as two litters per year, averaging 5-6 piglets – and as many as 14 – per brood.
Boar become sexually mature when they reach about 35kg. If food supplies are plentiful early in life, females reach breeding age well before their first birthday.
Meanwhile, their taste for junk food or crops such as corn and cereals boosts fertility: wild boars that feed on such a high-calorie diet, scientists observe, produce larger litters, and more often.
Olvera observes something else. “Urban boars,” he says, “live large and fast. They die younger than the boars of the forest.”
Wild boar are smaller than the farmyard pig, but they are growing more prodigious.
Some are so accustomed to human foods (they love factory-made cat food, too), they are becoming obese. In the autopsy lab on UAB campus, Olvera’s colleague Fuentes cut back a piece of an exterminated urban boar’s midsection revealing a thick layer of spongy tummy fat.
He measured up the girth between his thumb and index finger. “In boars, it should be half that,” he told me. (UAB autopsies routinely reveal in the stomach traces of rubbish, including pieces of plastic, and undigested human-prepared foods such as chicken and sandwich meat.)
Swine, or sus scrofa, have confounded humans for millennia, since pigs were domesticated 9,000 years ago.
Keeping pigs penned in is not always easy, and the ones that escape adapt to the wild in a matter of months. They don’t just change their habitat, but also behaviour and appearance in subsequent generations.
They grow a coat of coarse hair. Their tails straighten. Tusks lengthen. They become super-adapters, shape-shifting problem solvers with speed and agility.
“Wild pigs can run up to 30 mph. They can jump over fences less than 3ft high and have ‘climbed’ out of pig traps with walls 5 to 6ft high,” writes Billy Higginbotham, a wildlife conservation expert at Texas A&M AgriLife Research.