Our plan the first day was not to kill the beast, but to follow him, to observe his home and habits, to see the evil that he did and maybe get in his face.

For this, Sonny took me to Mau­na­wili, a neighborhood tucked beneath the razor-ridged Koo­laus on the Windward side of Oahu. He parked his truck at a house at the forest’s edge, put on camo gear, boots and backpack, and led me to a path behind a swimming pool that plunged into the jungle green.

The bright sun gave way to dappled darkness. Octopus trees, their rubbery leaves splayed on umbrella spines, wild ginger, thick-trunked avocado and mango trees, a lush understory of ferns and pili grass — we were in a classic Hawaiian wilderness, but a damaged one.

Sonny pointed out the signs. The eroded trails the beast had trampled, ravaged stream banks and fields of blackened muck he had nuzzled and plowed with bladelike tusks, looking for roots and worms. We saw his muddy wallowing spots. We saw droppings. We saw cloven hoof prints — his own and the tiny pairs of dots, incongruously dainty, left by his abundant and ravenous spawn.

Under an avocado tree, Sonny stopped, a finger to his lips.

We stared across at a low thicket of ferns. The fronds swayed and shuddered, and I caught a glimpse of a splotch of darkness that could have been a shadow, or the black bristling snout of feral boar.

Sonny took out his hog call, a tube with a reed and a rubber squeeze bulb, and trumpeted a soft, low grunt. Then he made chomping noises with his mouth. He had told me that pigs, being pigs, chew with their mouths open.

"They call them pigs because they eat like pigs," he explained.

The idea was to make the pig think another pig was eating his lunch. Chomp, chomp, went Sonny. I thought, I can do that. I smacked my lips the way you do when trying to get a 5-year-old to knock it off. Sonny rustled leaves to heighten the illusion of careless grazing: swish, swish.

Chomp, chomp. Grunt. Swish.

The boar went no farther. We waited. We soon realized he had melted, unfooled, back into the underbrush.

It’s like that with wild pigs.

"They’re very well educated," Sonny said.

A LICENSED FISHING and hunting guide, Sonny Thater is a professional pig eradicator, on call for homeowners and businesses with nuisance pigs, and for tourist hunters looking for an unusual trophy. He is one of many in Hawaii who grew up hunting pigs, a tradition that dates at least to the islands’ plantation days of the early 20th century. Sonny is one of the few who have made a business of it. He is thickset and wears his hair in a bristle cut, yet even when dressed head to toe in camo and holding a bayonet, he looks gentle, like someone who’d bring you coffee and doughnuts if you asked.

I had found Sonny online, at hook­you­up­out­fit­ters.com. Everybody knows that Hawaii is an imperiled Eden, a global hot spot for threatened and endangered species. Even though I had grown up here, I had never done much to help until I thought to kill some pigs. It seemed like a righteous mission, and Sonny was going to guide me.

The story of the Fall is this: Somebody in the Garden eats what he’s not supposed to and messes things up for everybody else. Hawaii’s hospitable habitat has long been overrun by opportunistic outsiders: feral sheep, feral goats, along with mongooses and exotic birds. Hoofed livestock brought by Europeans has done the most damage, and with their boundless appetites and unchecked fertility, Eurasian feral pigs, Sus scrofa, are the worst. These are not the little Asian domesticated pigs that Native Hawaiians farmed for centuries, but descendants of the big European swine that got loose and went native after Capt. Cook put Hawaii on the map in 1778.

"They rototill the planet," David Duffy, a biology professor at the University of Hawaii, told me.

On my visit in February, he and Thane Pratt, an authority on Hawaii forest birds, explained the problem. Feral pigs eat native plants and, through their scat, spread invasive ones like the forest-clotting strawberry guava. Indirectly they slaughter birds — the stagnant, mucky wallows they dig breed mosquitoes that carry avian malaria.

Their only redeeming trait is that they are delicious, which was the other reason that, two days after our Mau­na­wili probing expedition, Sonny took me out for the kill.

WE HAD HOOKED UP with members of the Pig Hunters Association of Oahu — Miles, Greg, Eddie, Boomer, Buddy, Dakota, Duke, Max, Miracle, Rascal, Shadow and Spunky — and well before sunrise on a Friday, we headed to their favored hunting grounds in Halawa Valley.

Miles Fukushima and Greg Tanaka have hunted together for years, and now that they are retired from their day jobs — Miles drove a garbage truck and Greg delivered the mail — they go out twice a week, every week, for pigs. The others were dogs, mostly variations on Rhodesian Ridgebacks, Miles said. They rode in a cage in Miles’ pickup like commuters on a rush-hour train.

Pig hunting in Hawaii is done with dogs, not guns. Dogs and knives. The dogs chase the pig; you chase the dogs. The dogs pin down the pig, which you finish off with the knife. This method is considered safer than shooting (stray bullets on tiny, crowded islands, no good) and more reliable, since pigs are cryptic, elusive and smart. Good dogs with good noses give human hunters the edge they lack.

I am not an animal killer, except for fish, and the thought of close-quarters combat with a tusked mammal almost my size gave me pause. Miles and Sonny told me to grab the pig’s left hind leg with my left hand and hold on, then with my right hand, push the blade behind the shoulder, into the heart.

"Don’t do the ‘Psycho’ thing," Sonny said. "And watch out when he jerks his head back to bite your hand off. Don’t take the knife out."

I decided I had to do it — it would be an exercise in ecological balance, a small act to help save little forest birds from extinction. When the moment came, I imagined, I would take no pleasure in it but just do my job, perhaps whispering into the pig’s ear, "This is for the oo bird. The mamo. And the poouli. Aloha, bruddah."

Perhaps then the pig would grasp the horror of what its species had done. That was the plan. It did not work out that way.

We followed a rutted road up in the valley, past the razor coils of Halawa Correctional Facility, and parked beside a grove of banana trees. Miles put GPS collars on the dogs. He had a receiver that rendered the dogs as dots on a contour map so he would always know where they were.

Miles is 67 and looks at least a decade younger, with steel-gray hair and mustache. With his quiet demeanor and guava walking stick, he seemed like a tropical Gandalf. He was the boss. When he walked the dogs walked. When he sat they did, too.

The dogs worked as a team, crisscrossing the trail up and back, sniffing and bolting and returning. It was like every chain-gang-escape movie you ever saw, without the baying and the shotguns. The dogs were quiet; the knives were sheathed.

We walked in single file along a stream, and I soaked in the scenery, recalling the pleasure of hiking in Hawaii. Its forests have no scary reptiles, no vicious poisonous plants; the only real hazards are mosquitoes and slippery streambeds.

HALAWA IS A valley of staggering beauty. We passed stands of wild orchids and a colossal breadfruit tree. Farther back, the exotic species shared space with native ohia lehua trees, whose red pompon blossoms are favored by endangered birds. I saw an Oahu ama­kihi, a honeycreeper, olive green and yellow with a curved bill: a prize sighting. It almost certainly had malaria.

We crouched as we walked under densely matted hau trees, their ropy branches strewn across the trail. It was like having a meatball’s-eye view of spaghetti.

We stopped to rest. The dogs marked the territory and we compared knives. Miles’ was hewed from an automobile spring, double-edged, and looked like a miniature cutlass. Greg’s had a hand-carved wooden hilt that could have been an eagle’s head, or a fighting chicken’s. As we sat around, Greg told a story of being stalked once by a submarine-size tiger shark while spearfishing. He found it funny; I found it terrifying.

We talked about recipes. Sonny likes to grind wild pig into linguica, Portuguese sausage. It tastes good — "spicy and herby," he said — but you have to add extra fat because the meat is so lean.

We ate frozen longan and tossed the pits. We picked tangerines from a soaring tree that Miles had accidentally planted from years of tossing seeds and rinds into a gully at the same resting spot.

We found remains of an old stone wall. We found trash left by other hunters. We found pig tracks and trails. What we didn’t find was a pig. All day the dogs remained mostly quiet and calm, poking around for a boar they couldn’t find.

I imagined him in the stream, just under the surface, a reed to his lips as the dogs splashed and sniffed. Miles decided to call it quits at about 5 p.m., as it started to rain softly. I went home with memories of a lovely hike, and two bags of wild tangerines.

Sonny felt so bad that he gave me a mess of pig — ribs and tenderloin — from his freezer. I used my mother’s garden pruners to clip the ribs to oven length, then braised and broiled them. The tenderloin became kalua pig, oven-roasted with rock salt; Okinawan rafute, boiled with sake and soy sauce; and adobo, Filipino stew with coconut milk. I made a feast for my family and ate to ease my dejection.

"I wish you had been here last week," Sonny said. Or the next when the following Friday, he took out a client from Canada named Rylan. The dogs found a boar, chased it into the streambed, and Rylan stabbed it. He carried it home, piggyback.

Sonny texted me photos of Rylan with his trophy, all huge tusks and reddish bristles. One more pig down, I thought. A few million more to go.