In Hawai'i, people, pigs, and ecosystems only have so much room to coexist, and the pigs exist a little too much.
This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.
Francis "Bully" Mission Sr., president and founder of Mission Animal Control, is in a good mood when I meet him at a strip mall parking lot on the south side of the Hawaiian island of Kaua'i. He and his son Levi have just found two "squeakers" -- pigs no more than a few months old -- in one of their traps, which means US $100 in their pockets and another satisfied customer. Property owners all over the island hire the duo to remove problem animals, and Bully has invited me to join him as he collects the new captives.
"We had a big mama yesterday and three juveniles," he tells me as I climb into his pickup truck. "The population is unbelievable."
Inside the cab, I notice what appears to be Old MacDonald's entire farm glued to the dashboard: a plastic cat, a couple of horses, a cow, and three pigs. These are all species that humans have brought to the Hawaiian islands and that the Mission family is often hired to eliminate. Feral pigs, once denizens of the mountains with intermittent forays to lower elevations, have become regular raiders of lowland farms, upscale neighborhoods, and members-only golf courses. "Some of them look like you could put a saddle on them and ride them," Bully says of the pigs he's seen.
Pigs can now be found on six of Hawai'i's seven inhabited islands, and their impacts are especially profound on Kaua'i, the lush "Garden Island," which has so far retained much of its native character. Its mountains are home to 255 unique native plant species and 208 native birds, including 11 found nowhere else on Earth. As the pigs tear up vegetation, they encourage erosion and muddy the island's drinking water supplies. Their wallows breed mosquitoes that spread avian malaria, contributing to 10 of Kaua'i's 16 native honeycreepers going extinct. They also spread the seeds of the strawberry guava tree in their dung, contributing to what one group of researchers has referred to as an "invasional meltdown." The guava shades out native plants and smothers them in its leaves.
The pigs' presence in the populated lowlands has grown over the last couple of decades. Sally Rizzo, who was running an organic farm during my visit, told me that the pigs broke through her fence this year and "shit all over our baby greens." On the roads, drivers frequently have to swerve to avoid pigs, leading to several hundred accidents every year. Beaches aren't safe either. Three years ago, a tusked boar made headlines when it went for a swim and thrashed a surfer in the lineup off Oahu, another island. On oceanside bluffs, meanwhile, the pigs are preying on the chicks of migratory seabirds, so completely trashing their burrow nests that the birds never return to them again.
Despite the damage that feral pigs are causing, you can't just shoot them on sight as you can in many other US states. In Texas, home to more than one-third of the seven million feral pigs in the United States, hunters and landowners target them from helicopters or with poison baits. On Hawai'i, however, pigs occupy a more complicated position, as their populations are managed for both recreation and subsistence. Along with West Virginia, Hawai'i is one of two states with bag limits on public land. This means that while conservationists are trying to reduce or eliminate pig populations inside protected areas, the Hawai'i Division of Forestry and Wildlife manages the animal as a limited resource just about everywhere else.
Bully, who is of Portuguese and Filipino descent, used to be the island's chief game warden and thinks if there was a little more hunting access in the lowlands, the pigs wouldn't be such a headache. Now in his early 60s, he learned how to hunt pigs while growing up on a sugarcane plantation where his father worked. Hunting pigs was a perk of his dad's job and part of the Hawaiian culture. Bully joined the US Navy at 17 and became a police officer after his service. He then spent 20 years as a game warden, retiring in 2017. That's when he got into the animal control business. One of his first jobs involved eradicating animals on a seed corn farm. "I took out 12 wild cattle and about 300 pigs," he says.
We turn onto a two-lane asphalt road, stained red from the island's volcanic dirt, and arrive at an ornamental flower farm, though there is nary a flower in sight. Most of the irrigated land is a boggy mess. Bully points out a single cluster of wax-like Asian beehive gingers still on their stalks, which look like miniature cartoon beehives. The owners don't want to talk to me, but Bully says they have seen more than a dozen pigs on their property over the past couple of months. The damage is so extensive they are unable to fulfill their contracts.
We walk toward Bully's cage trap, which is about the size of a refrigerator lying on its side. The two squeakers freeze when they spot us and then grow frantic as we approach. Porky pigs, they are not: they are lean and have coarse black hair, thinning in spots. It's starvation season for the pigs. Guava, one of their staple foods, is not fruiting in the mountains, so they come down here to root around for earthworms in what has become a seasonal migration.
One of the pigs climbs up the trap's wire mesh side and samples our scent with its fleshy gray snout. Levi raises the wooden trapdoor, and Bully shoos the animals into a smaller cage positioned at the opening. When the pigs cross the threshold, Bully flips the small cage onto its side. He swings the mesh door shut, and then he and Levi carry it out to a rack on the back of the truck. If they were larger animals -- like the mother he captured the day before -- Bully would shoot them on the spot and roast their meat. "If I dispatch a small one, you know, it's not really that much to eat," he says. Bully eats pork that he traps about twice a week and gives away a lot of it.
These squeakers will go to a friend who will fatten them up at his farm over the next year or so, until they are closing in on 150 kilograms. In other words, a size worthy of a luau. Pigs may be a menace, but they are also a meal, and that's a big part of the paradox: the relationship between people and pigs can be mutually beneficial -- or mutually destructive.
Pigs aren't native to Hawai'i, but they have been here for a long time. When the English navigator Captain James Cook approached the coast of Kaua'i with his ships HMS Resolution and HMS Discovery on January 19, 1778, locals paddled up in their canoes with "roasting-pigs, and some very fine potatoes," as Cook later wrote in his journal.
But the animals that Cook -- the son of a Scottish farm worker -- encountered during his exploration differed from the English pigs that he carried in the hold of his own vessel. Weighing just 25 or 30 kilograms, the Hawaiian swine were one-tenth the size of their hefty English cousins; they had a long snout and their ears were not cute and floppy but erect. These were the pigs that the Polynesian people had brought with them from Asia, as they hopped from island to island, beating Cook to Hawai'i by 1,000 years or so.
Cook's landing represented not only a clash of civilizations but also a reunion for these two long-isolated lineages of domesticated pigs. At some point during his Hawaiian sojourn, Cook released at least one pair of his animals on the island of Ni'ihau. This was just the first of many introductions of the larger, and -- some have claimed -- more destructive, European pig breeds in Hawai'i. The two breeds intermingled extensively on the islands, and they possess a globally distinct mix of genes, including a unique mutation that controls their black coat color.
Both European and Asian pigs descend from the most widespread and adaptable species of swine on the planet, the wild boar -- Sus scrofa -- whose native range likely extended across most of Europe, North Africa, and Asia. Wild boars are one of 18 species of Old World pigs, or swine, which include the warthogs of sub-Saharan Africa and the tusked babirusas of Indonesia. (Boars are not native to the Americas, but we do have the very boar-like peccaries -- close cousins to the swine.)
Humanity's great "porkification" project began somewhere around 7,000 to 10,000 years ago, when people in both China and the Middle East settled down, began raising crops, and realized they had a problem on their hands. Because boars are clever creatures with an omnivorous diet, they likely became a pest around these new settlements, destroying crops and fouling waterways. They were less man's best friend; more man's worst frenemy. According to one scenario proposed by archaeologists, humans would kill troublesome sows and raise their piglets in captivity. Women may even have breastfed the young ones, as has been documented among Indigenous communities in southeast Asia, Melanesia, and Australia.
"Pigs are so petted and cosseted that they assume all the characteristics of dogs -- hang their heads under rebuke, snuggle up to regain favor, and so on," the anthropologist Margaret Mead wrote in a 1932 letter from a mountaintop village in New Guinea. Eventually, people began breeding for desirable traits among their cohabitants. They selected animals with unusual pigmentation -- rosy skin and piebald patterns -- perhaps to make them easier to find in the forest, to set them apart from their wild brethren, or simply for the novelty of it.
Pigs also turned out to be portable. Almost three centuries before Captain Cook ventured across the Pacific, the modern "Age of Pigsploration" began with the Spaniards, who rank among the globe's most enthusiastic porkophiles. (A typical Spaniard consumes 54 kilograms of pork per year, more than twice as much as an average Canadian.) In 1493, Christopher Columbus, who was born on the Italian coast but sailed under the Spanish flag, released eight Iberian pigs in Cuba, hoping to provide a self-sustaining supply of meat for future settlers.
Forty-six years later, Hernando de Soto picked up 13 of those Cuban pigs and released them in Tampa, Florida. Among other distinctions that the brutal plunderer attained during his decades-long conquest of the New World, the US National Pork Board has dubbed him "the father of the American pork industry."
By 1982, feral pigs in North America could be found along a thin band from Florida to the Texas Gulf Coast, along with parts of California. Today, they have been documented in 35 states and at least six Canadian provinces (where boar farmers set their animals free after the market for boar meat peaked in 2001 and then crashed). Part of the reason they have spread so widely is that females can sometimes begin reproducing at just three months, and they can have a dozen or more piglets every year over their six-to-eight-year life spans.
"Wild pigs are the ultimate survivor," says Jack Mayer, a zoologist at the Savannah River National Laboratory in Aiken, South Carolina, where he has studied hogs for over 40 years. "They can reproduce for a long time, they are very secretive, and they are very smart." In Canada, feral hogs burrow into mounds of cattails they have gathered, creating snow-covered "pigloos" that will keep them warm through the harsh winters.
It's just after sunrise on Kaua'i. Amid the thumping of a helicopter, a conservationist named Nicolai Barca inserts two blue plugs into his dog's ears and slips a pair of muffs over his furry head. He and Tako climb into the back seat of the chopper, while I grab the front with our pilot. The ground falls away, and in one stomach-churning swoop, we see the breakers crashing against the cliffs on the south side of Kaua'i and then -- veering toward the stormy center of the island -- the cloud-shrouded summit of Kawaikini. Rain flecks our windshield. The canopy below explodes with the red blooms of native 'ōhi'a trees.
Barca, who grew up on Kaua'i, is a field manager for The Nature Conservancy of Hawai'i. He is taking me to one of the remote areas where he works, known as the Drinking Glass Unit, which is located near the center of the island and would take days to reach on foot. It is one of the last intact forest ecosystems on the island -- or the closest thing to it anyway. "The hunters are the de facto owners of the mountains because they're the only people who come here," he says.
When we land in a small clearing, the three of us hop out and duck near some bushes as the helicopter departs. We are now all alone in the wilderness, and I take in the incongruity of what is before me: a 2.5-meter-tall hog-wire fence cutting through the tree ferns and 'ōhi'a. The fence forms the border of the Drinking Glass Unit, an exclosure which abuts three other fence units that Barca also monitors, all part of a public-private partnership called the Kaua'i Watershed Alliance, one of 10 such partnerships on five Hawaiian islands meant to protect the land and water. Taken together, the fenced exclosures on Kaua'i comprise 4,500 hectares of forest, nearly the size of Manhattan.
Standing outside of this complex maze of fencing, Barca loads his rifle and swings it over his shoulder, just in case he sees something inside the fence that's not supposed to be there. Pigs, maybe. Or introduced deer, which are the reason the fences now have to be so tall. Barca's plan for the day is to take a few pictures of the vegetation, check some of his snares, and replace data cards in the game cameras -- the best way to keep track of who and what is coming and going. He also plans to release an insect that acts as a biological control agent to dampen the guava plant's vigor and give the natives a fighting chance, which is really what his job is all about: preserving the biological integrity of Kaua'i's mountaintop forests.
Barca gives Tako a boost through an elevated gate, and we make our way along the outside of the perimeter. He squats and reaches down for a piece of animal dung. "Pig," he says, breaking it apart with his fingers. He examines several strips of undigested vegetation, the fibrous remains of a fern leaf. "She's probably in this general area right now," he says, looking around suspiciously. On the inside of the fence, Tako pauses and raises her muzzle.
A few steps away, Barca finds a whorl of matted straw -- strands of a native sawsedge -- where the pig recently bedded down with her young. She uprooted a whole patch of this Hawaiian endemic to build her nest. When the sedges are destroyed, the invasive grasses move in. "There seems to be this progression in most of the native forest where they are getting less and less native," Barca says.
Beyond the direct impacts that pigs cause to native ecosystems through their foraging, they may also be setting off an ecological cascade with profound consequences. Steven Hess, a researcher with the US Department of Agriculture, has found that there are about 40 percent more earthworms in areas where pigs actively root. Despite their beloved reputation among gardeners, earthworms are not native to Hawai'i, and as they burrow and poop, they loosen and fertilize the soil and create ideal conditions for nonnative plants to thrive and outcompete island-adapted natives. "Pigs are out there mixing leaves into the soil and aerating the soil, and worms love that," Hess says. "Pigs may come back and eat those worms later." In other words, feral pigs raise their own livestock.
The Kaua'i Watershed Alliance came together in 2003 as part of a statewide goal to protect 30 percent of Hawai'i's "priority watershed forests" -- namely forests that had lots of native plants and were crucial for keeping streams flowing and replenishing underground aquifers. To reach that goal, the 11 members of the Alliance, which includes the state of Hawai'i and large landowners like the McBryde Sugar Company, charged The Nature Conservancy with drawing up a plan for Kaua'i. Any strategy would have to focus on eliminating invasive plants and animals. Kaua'i's cliffs and knife-edge ridges already form natural barriers for pigs and deer, but the organization would have to augment them with an ambitious fence-building effort in rugged highlands.
On Kaua'i, one of the first major projects the Conservancy embarked on was a seven-kilometer-long hog-wire fence completed in 2010 to protect the Alaka'i plateau not far from where we are today. Over six years, Barca says, native plant cover in the understory increased by 25 to 35 percent. With the success of that fence came four more exclosures, including Drinking Glass and one in the neighboring Wainiha Valley, where researchers have recorded 37 pigs per square kilometer. In terms of large-mammal densities, that ranks with Uganda's Queen Elizabeth National Park, an area so rich with grazing animals that scientists suspect it resembles Earth during the Pleistocene. Two more pig-free exclosures are currently in the works on Kaua'i.
Pig removal is not only happening as part of the watershed conservation effort. Along Kaua'i's northern coast, the Kīlauea Point National Wildlife Refuge recently completed an even more elaborate fence that can also keep out cats and rats to protect seabird nesting sites, including threatened Newell's shearwaters and endangered Hawaiian petrels. After the fence was completed but before the pigs could be removed, they wiped out between 70 and 80 eggs of the Laysan albatross in a span of just two weeks. The birds typically lay one egg per season. "We caught pigs shoving adult birds off of their nests and then eating the eggs out, or just eating the eggs out right underneath the birds," says Dylan Blanchard, who monitors wildlife inside the fence for Pacific Rim Conservation, which helped lead the effort.
Many of the new fences on Kaua'i and other islands have proven controversial among hunters, including native Hawaiians, who have already had their access to land blocked by wealthy landowners erecting fences around their private Xanadus. "The only invasive species is the white man coming in the forest and fencing," reads one public comment submitted in response to a fencing proposal on the island of Hawai'i, also known as the Big Island.
Barca, who also happens to be a pig hunter, is looking for a way through this impasse, but he knows it's not going to be easy to get the hunters and conservationists to work together. "A lot of hunters are fearful," he tells me. "I even have a friend who thinks they're gonna fence from the mountains down to the ocean." The truth, Barca says, is that across Hawai'i, three-quarters of forests will remain wide open to pigs under statewide watershed protection targets. Whether hunters will continue to have access to all the land they once hunted on is another question.
To understand the emotional stakes here, it's helpful to learn the story of Kui Palama. Around 7:00 a.m. on January 17, 2011, Palama loaded up his mule and followed a trail up Kaua'i's Hanapepe Valley with his dogs in tow.
He was venturing from his taro patches to a place called Kupo Ridge, where he and his family -- his ohana -- had hunted for generations. "One of the most beautiful places on Earth here on Kaua'i," is the way he later described it in court testimony. It was open country with clean water, abundant fruit trees, and pigs. "Plenty pigs for us to survive," he said.
His dogs caught the scent of hogs. They chased one down, surrounded it, and latched their jaws onto its flesh to hold it in place until Palama could approach. Palama drew his knife and pierced the pig's throat. He then hung the animal from a tree to let the blood drain. Next, he removed the skin and cut the muscle into pieces, which he stashed in his meat bags.
The problem was that Kupo Ridge is not public land. It has been owned by the Robinson family for more than a century. With 20,000 hectares to their name, the Robinsons are the largest private landowner on Kaua'i, controlling a pie slice that covers one-seventh of the island. (The family also owns the entire island of Ni'ihau to the west.) Before Palama got back to his truck, he was approached by two Robinson employees, who told him he was trespassing. The state of Hawai'i filed charges two months later.
The Palama clan wasn't having it. One Robinson family member, Alan Robinson, testified that a relative of Mr. Palama left him several threatening voice messages, including one in which he said, "you messed with the wrong family." With the backing of the Pele Defense Fund, a nonprofit that defends native rights, Palama ended up successfully getting the charges dismissed in December 2015. At trial, a historian from the University of Hawai'i, Jon Kamakawiwo'ole Osorio, testified that "hunting pig is traditional and customary to Hawaiian culture, religion, ohana," according to a court transcript.
Despite a ruling in Palama's favor, there is some debate about how widespread pig hunting was prior to European contact. Osorio's documentary evidence was limited. (Osorio declined to comment, and the Palamas could not be reached.) Palama's style of hunting, known as dog-and-knife, is generally thought to have been introduced by the Portuguese. Moreover, prior to Cook's arrival, native Hawaiians had largely kept their pigs corralled. After all, their irrigated taro fields and sweet potato crops were incompatible with free-range swine.
Conflict and social changes brought on by colonization and the privatization of land in the 19th and 20th centuries forced Hawaiians to swap their family farms for work at company-run plantations. The pigs they abandoned spread across the islands, their only predators hunters, the people who formerly corralled and cared for them. "There were no beasts of prey, nor any ferocious animals, except the hogs, which were sometimes found wild in the mountains," the missionary William Ellis wrote in his account of an 1823 tour through Hawai'i, which might just be the first written record of feral pigs on the islands.
Over the next century, they evidently became quite numerous, but hunting pressure around the plantations kept them confined to the mountains. In the 1930s, George Munro, a naturalist from New Zealand, became concerned enough about the impact of feral pigs on the cloud forest on the tiny island of Lāna'i that he eradicated them -- a feat that is not likely to be repeated on any other island. Seventy years later, fencing would become the solution of choice on the larger islands.
In the aftermath of the Palama case, native rights are often the first issue that gets raised every time a new fence is proposed. One evening, I visit Billy DeCosta, a schoolteacher who sits on the Kaua'i County Council. He is of Portuguese descent but is one of the most vocal defenders of pig hunting on the island, and a number of native Hawaiians pointed me in his direction. At the entrance to his property, there's a large wooden sign that reads Wild Bill's Ranch, adorned with a longhorn skull and a couple of horseshoes.
When I pull up, more than a dozen tan-colored dogs, indistinguishable apart from the patterns of scars on their bellies, begin barking. A shirtless man in swimming trunks hurries out to greet me. Wild Bill's gray hair is slicked back into a kind of mullet. Tattoos grace his bare chest and muscular biceps.
"I'm not sure if you're a strong environmentalist or not, but I need to tell you, a boar got my dog last night," he says. His dog Brownie has a fresh wound, deep and pink. DeCosta, a veterinary school dropout, says he isn't going to try to staple it shut as he usually does. He'll just give Brownie a few injections of penicillin. "The dogs lick each other and keep him clean," he says.
While I'm slurping down the salty broth of DeCosta's chunky boar and papaya soup, he tells me how many locals, including his own Portuguese forebears, grew up on sugarcane plantations, where they were free to hunt on their time off. For a few generations, locals could informally access plantation land to hunt and feed their families. They could continue their subsistence traditions, at least until the plantations were subdivided and sold off to new arrivals like Mark Zuckerberg and Bette Midler, who began controlling access to their compounds with gates, walls, and fences. "People cannot go hunt like they used to," he says. "Shame on the American people who stop cultural heritage."
He doesn't have a problem with a fence here or there to protect an individual tree or endangered seabirds, but he doesn't think the fence units need to be so large, which restricts the seasonal migrations of his quarry. "The environmentalists got to keep having fenced areas so they got a job," he says, verging on conspiracy-theory territory. "The more acres you have designated, the more federal monies come down."
Back near the Drinking Glass Unit, Barca and I descend toward a boggy area where a rocky stream crosses under the skirt of the fence. The waters are cool and clear -- a precious resource on an oceanic island. Barca points to a gap that could easily allow a pig to invade. If there's a hole big enough for a pig, then a pig has likely already slipped through.
Maintaining all these fences is a never-ending task, though the funding is never enough, despite what Wild Bill thinks. A single tree falling in the wrong place can compromise an entire unit. Hunters also like to cut holes in them out of spite. "It's amazing," Barca says. "They don't think there's enough room for hunting."
The Nature Conservancy has tried to mitigate these conflicts by advocating for hunting access. The island of Moloka'i is mostly held in private hands. But many of the island's 7,000 residents depend on subsistence hunting for pigs and deer, and the Conservancy has negotiated with landowners to provide gate keys to community members so that they can continue to reach their hunting grounds.
Barca, who sits on Kaua'i's game management advisory committee, says that the future of Kaua'i's ecosystems depends on getting conservationists, hunters, and landowners to work better together outside of the protected fenced areas, where the majority of forest land lies anyway. Hunters shouldn't fear that pigs will be entirely eliminated from the island. In those unfenced areas that are already severely disturbed, he says, it's better to keep up the grazing pressure from pigs and deer to prevent invasive plants from taking over completely. "I'm really interested in how you manage the animals in these areas that are outside the fences," he says.
At the annual Hawai'i Conservation Conference a few years ago, Barca saw a presentation featuring a Kobe plot -- a staple of fisheries management that shows how fishing pressure affects the abundance of a stock. He began thinking about adapting the concept for pigs. Instead of fishing pressure, he would use browsing pressure; instead of stock abundance, he would come up with a score for vegetation health. "In theory, if the animals go down, the vegetation should go up," he says.
He's still developing the model with data he has collected, but Barca believes such plots could help the state set quotas in different game units to increase hunting in the most impacted areas. Barca thinks seven or eight pigs per square kilometer will be the sweet spot to keep weeds in check while not causing too much damage to the land. On the island of Hawai'i last year, the agency relaxed hunting restrictions at three forest reserves because of the impact of pigs on the surrounding communities. Similar changes could be directed toward conservation goals. "The hunting community and the conservationists can work together to try to hit that mark," Barca says.
As we fly back to the coast, we take a detour over several ridges on the north side of the island and descend into the upper reaches of the Hanalei Valley. There are no fences here. Barca has his helmet pressed to the glass as he scans the green valley below. The brush sways in the wash of our rotor. A massive black boar bursts out from the bush. It circles along the river's edge in a fury of confusion and terror, and then, just as abruptly as it had appeared, it vanishes again under thick cover. Barca has shifted from conservationist to hunter, but then again, maybe there is little difference out here.