Texans have penned them in state-of-the-art traps, tracked them with night-vision goggles, massacred them with machine guns and and even shot them from helicopters.
But despite all the firepower and ingenuity the Lone Star State can muster, it is losing the war on feral hogs. The population of one of the most invasive and destructive wild animals in the United States is growing rapidly. And now they are trotting inside city limits.
What was once a largely rural problem is blighting suburban areas near parks and lakes. The city of Dallas has contracted a company to catch the swine starting next month after discovering that they are causing damage only a couple of miles from the heart of downtown.
"They've come to downtown Dallas using the flood plains, using the levees," said Kevin Acosta, a city employee. "We've already had damage in parks, trails, city building locations near our landfill. Rooting with their nose they can dig two-to-three feet below the surface. They kill, in a sense, the ground – you'd think a machine had come through.
"We've seen the damage they can do in some of our parks where we have plants growing ... we don't have exact numbers but we do know they are increasing. When you look at the spots, you'd be surprised: 'they went here?' 'How did they get here?'"
Dallas created a task force to tackle its pig problem and it is cooperating with affected neighbouring cities such as Arlington and Fort Worth. It is illegal for civilians to discharge a firearm inside Dallas' city limits so the hogs must be caught and then slaughtered elsewhere.
Texas A&M University's AgriLife Extension service conducts feral hog research and educates landowners. It has launched an online reporting system in a bid to track activity.
Mark Tyson, from the project, said that studies indicate there are between 1.8 and 3.4m wild hogs in Texas – about half the total number in the US. Some 79% of the state's land mass is a suitable habitat for them, and they have infiltrated almost every county.
Texas allows hogs to be hunted year-round and the state's many gun owners have responded to the "aporkalypse" with predictable enthusiasm.
Traps are also becoming more sophisticated, using wireless surveillance technology.
An estimated 750,000 of the animals are harvested each year – not enough to keep pace with the birth rate.
Tyson said that as things stand, the number of feral hogs in Texas is predicted to grow by 16% annually, roughly doubling in five years. They already cause an estimated $52m in damage to the state's agriculture industry each year. And they are becoming partial to the comforts of suburban life.
"They're roaming across the landscape searching for the best food sources available," said Tyson. "Irrigated, fertilised lawns offer higher-quality food resources than the natural environment. They can cover less area and get the same food benefits in an urban setting."
Hogs were introduced to Texas in the 1500s by Spanish explorers and cross-bred with imported European boars in the last century, according to the Texas Parks and Wildlife department. Adults are omnivorous, weigh from 100 to more than 400 pounds and have sharp tusks.
Mainly nocturnal, they can breed from as young as six months and produce litters of, on average, four to six – but up to twelve – piglets as often as three times every 18 months. Scouting for food, they damage crops, fields, trees and habitations and sometimes eat other wildlife. And they are cunning. "Feral hogs are very smart, right in there with the range of dogs as far as intelligence," said Tyson.
They feed often and have no sweat glands, meaning they cannot regulate their body temperatures so seek to cool down by wallowing. Though there have been reports of hogs colliding with vehicles and cyclists and of sows behaving aggressively to protect their families, their bathing habits could pose the biggest threat to humans.
"They distribute their fecal matter indiscriminately," said Tyson. "A lot of their feces ends up in the water or in the upland areas which wash into the water." That can increase bacteria levels. Some pigs carry swine brucellosis, which puts hunters at particular risk. It can be transmitted through skin wounds and inhaling bacteria and may cause flu-like symptoms and chronic organ infections in humans.
For years, the infestation has been so acute in George Bush Park, on the western edge of Houston, that in 2009 the commissioner responsible for the area, Steve Radack, claimed up to 15,000 hogs live in the park. He proposed allowing bow-hunters to shoot them and donate the meat to the homeless. The idea was rejected on safety grounds.
Across the country, hogs cause an estimated $1.5bn in damage annually.
Mark Smith, an associate professor at Auburn University in Alabama, is a co-coordinator of the bi-annual Wild Pig Conference, to be held in Montgomery next April. "People are definitely mobilising, [the issue] has definitely gotten on the radar," he said.
Smith said that feral hogs are established in 40-45 US states and have spread rapidly in the past three decades because hunters seeking convenient sport have trapped, transported and released them in new areas, only for the populations to migrate and spiral out of control. "Before you know it you're up to your neck in pigs," he said. "In Alabama we have pigs which are creeping into people's backyards."
Auburn scientists are in the early stages of attempts to research and develop a contraceptive. Given the limited effects of hunting and trapping, the best hope for population control is fine-tuning a pesticide such as sodium nitrite, which has been very effective in reducing Australia's hog problem. It is not yet authorised as a swine-control method in the US because of the risk it poses to other animals, such as bears.
At least there is one positive: hog meat is delicious. "It tastes real good," said Smith. "I made a batch into sausages."
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