A smear of caramel-colored mud coats a sapling at least three feet up its trunk. "That's a big pig," says professional hog trapper Paul Smith. "See this gash in the bark? That was made by its tusk – it would've been a big male, and it was here not long ago."
A beaten trail leads through the tangled jungle fringe to a small creek, where the banks on both sides are churned up – more evidence that wild pigs rule in this muggy corner of tropical Queensland.
Australia's lush forests and farmlands are hog heaven. But the wild boar are making it hell for everyone else. Blamed for an array of ruinous behavior to the environment and the crops, feral pigs are among the most destructive pests to be introduced by Europeans – and keeping their numbers down is becoming serious business.
The wild boar here are descended from the domestic pigs that 18th century European explorers such as Capt. James Cook released as a living larder for future expeditions. With plentiful food, a balmy climate, and no natural predators – aside from the occasional marauding crocodile and the piglet-poaching dingoes – the pigs flourished.
Government estimates vary, but suggest there could be up to 23 million pigs in Australia.
Feral pigs inhabit about 40 percent of the land, colonizing a range of habitats from forests and mountains to semi-arid savanna, according to the federal agency, Invasive Animals Cooperative Research Centre.
They have also grown bigger and brawnier than their British ancestors. Some razorbacks weigh more than 300 pounds, and the males are capable of goring a human with their formidable tusks.
The pigs are bad news for Australia. They prey on newborn lambs; damage fences; reduce yields of cereal grain, sugar cane, fruit, and vegetable crops; and spread disease, according to the research center.
They also harm the environment. In Queensland, wild boar dig and root along the banks of creeks and rivers, loosening the soil and making it vulnerable to erosion in the annual wet season. The muddy silt eventually washes into the sea and out to the Great Barrier Reef, smothering pristine reefs and killing coral.
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Mr. Smith is on the frontline of the fight against the burgeoning wild pig population.
He set up his pig trapping business, Boar Busters, two years ago after retiring from the Australian Army. During his 17 years in the military, he served in Iraq, East Timor, and Somalia.
He grew up in this sugar cane country, hunting pigs as a teenager. The pig-trapping venture enables him to put something back into the community and use some of the skills he learned as a noncommissioned officer in the infantry, he says.
"Some of the field craft that I learned comes in useful when you're tracking an animal. And logistical skills help me organize a small number of staff so that we can have the maximum effect on the problem," Smith says.
He and his trappers have caught and shot 1,200 pigs over the past two years in the dense rain forests and open farmland surrounding the sugar cane towns of Innisfail and Tully.
Pigs can reproduce at an astonishing rate. A sow can produce two litters a year, with up to 10 piglets in each litter. Within six months the young pigs are ready to breed.
Where farmers once shot a dozen pigs a year, they are now bagging hundreds. "The numbers compound very quickly," says Smith, checking his traps along a rutted track where forest meets farmland.
"We can't shoot them because the forest is too dense and we can't bait them because that would kill native wildlife, too. So we trap them. Big or small, we catch 'em all, that's our motto."
The traps are positioned in the shade – so that the animals do not suffer from heat exhaustion – and are checked daily. The pigs are shot with a rifle. Sadly for such an abundant resource, their meat cannot be eaten, due to worm infestation and disease.
"It's not something we get a kick out of," says trapper Simon Kaukiainen, as the sound of a rifle shot rings out through the rain forest, scattering a flock of snow-white cockatoos. "But it needs to be done."
The pig problem has worsened in this region after cyclone Larry barreled through in March 2006, flattening large swaths of rain forest. This deprived pigs of wild fruit and fungi, driving them onto farmland.
"Over the last 12 months, there have been extraordinary numbers," says Wayne Thomas, of Queensland Canegrowers. "The cyclone destroyed their habitat and displaced them."
Pig hunting has been popular with rural Australians for decades. Amateur pig hunters use high-powered rifles, hunting dogs, and "pig rigs" – specially equipped trucks – and call themselves "grunter hunters."
The sport even has its own magazines, like "Bacon Busters."
But amateur hunters are struggling to control pig numbers, and the battle is increasingly turning professional – hence the demand for Smith's services. Farmers pay him thousands of dollars to eliminate pigs from their land.
"They're a terrible pest," says Robert Collins, a veteran sugarcane farmer who employs Boar Busters.
"In more open country you can shoot them from helicopters, but here in the scrub [rain forest] you can't even see them."
Farmers are being financially hit by the depredations of pigs, which lay waste sugar cane and tropical fruit plantations. They are so robust that they can charge through electric fences.
Some banana farmers have lost up to 40 percent of their crop to marauding pigs. "In this region alone, losses are well into the millions," says Mr. Thomas.
Nationwide, the annual agricultural damage is estimated to be costing over A $100 million.
As well as raiding farms, the pigs compete for wild fruit with animals such as the cassowary, a giant flightless bird with a dangerously powerful kick.
"Only 1,200 remain in the wild in Australia, which makes them rarer than the giant panda," says Roger Phillips, head of the Australian Rainforest Foundation.
With their bright red-and-blue facial markings, cassowaries are physically striking, but they are also key to the health of the rain forest because they disperse the seeds of over a 100 species of tree. The seeds will only grow if they have passed through the cassowary's gut.
In Queensland's Daintree rain forest, a UN-designated World Heritage area, there are more tree species per hectare than in the whole of North America. Many rely on the cassowary for propagation.
"They'll eat fruit the size of a cricket ball and five minutes later deposit it in a nice little steaming pile of its own fertilizer," Mr. Phillips says.
"Trapping won't solve the feral pig problem – it's like the little boy with his finger in the dam trying to hold back the water. But at least we can remove pigs from critical cassowary habitat and try to hold the line."
Eradicating pigs from Australia would be impossible, say wildlife experts and government agencies. They are too numerous, they breed too quickly, and they are entrenched in some of the country's wildest and most inaccessible terrain.
"They're also very smart," Smith says as he winds up another long day chasing his formidable foe. "They have the cognitive development of a 3-year-old child. I've got a pretty healthy respect for them. People think they're dumb animals, but they're really not."