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Unwelcome Invaders: Wild Pigs Pose a Serious New Threat to Idaho

Exotic species threatens agriculture, the environment and wildlife


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The damage wild pigs can do is both very real and extensive. From the Department of Agriculture's perspective, top concerns include the destruction of crops and rangeland, as well as the possibility of transmitting diseases from wild pigs to their domestic counterparts and jeopardizing the state's livestock industry standing.

Wild pigs' most common foods include roots, tubers and assorted vegetation, and they are able to get to those food sources with impressive efficiency. They use their snouts to root below ground level, tearing up surface vegetation. This not only gets them a good meal, but it means that a group of pigs--known as a sounder--can effectively take out an agricultural field overnight.

This rooting activity also makes them the bane of wetland and riparian areas since not only does the rooting lead to erosion, but increased sediment in the water can damage fish spawning areas. Additionally, the rooting can make it all the easier for noxious weeds and other invasive plant species to take hold.

Wild pigs--as well as domestic pigs--are equal opportunity eaters, meaning they will eat just about anything if given the chance. This puts everything from amphibians and worms to ground-nesting birds and their eggs to the occasional lamb or calf on the menu.

Idaho Fish and Game officials are particularly concerned with ground-nesting bird populations, including ducks, geese, pheasants and quail. Concerns are especially significant considering the area where the pigs are active overlaps a wildlife conservation area that is the nesting ground for a large population of waterfowl.

Flatter said there is evidence the pigs have been taking advantage of the birds.

"They're pretty opportunistic," he said. "Given a nest full of eggs, they'll eat them."

Just like the dietary preferences of wild pigs, the diseases they carry aren't too particular. Wild pigs can carry diseases that have been largely eliminated from domestic livestock, including swine brucellosis and pseudorabies. Unfortunately, some of these diseases aren't species-specific and can jump not only to wildlife but to humans as well.

The swine form of brucellosis (slightly different from the form found in large ungulates like elk and bison in the Yellowstone area) not only can kill animals but can be contracted by hunters while handling the carcass of an infected wild pig if they don't wear protective gloves. If a human is infected, the disease usually causes flu-like symptoms.

Pseudorabies is a form of the herpes virus and is not only fatal to wildlife but is of particular concern to hunting dogs.

"The unfortunate part [is] that with feral swine, they can harbor so many diseases but live with it ... if it gets into [the domestic] population, the amount of resources to control that are going to be enormous," Stopak said.

Wildlife Services has taken samples of all wild pigs trapped in Idaho, and to date, there have been no positive results from tests.

It's because of the health risks that livestock groups, including the state's pork industry, are supporting efforts to eradicate wild pigs, including providing financial support.

"Idaho is a brucellosis-free state and pigs could jeopardize Idaho's status," Flatter said. "You don't want to have that kind of a mark on your state. You don't want any potential negative issues.

"Anytime you bring wildlife into the state, it has to be inspected," Flatter said. "We don't have [native] wild hogs here. If any are brought in, the Department of Ag would not let them into the state ... Any time you're releasing wildlife, it just causes problems."

The wild pigs issue is one of the rare moments in which wildlife managers, agricultural groups and conservation groups are on the same side.

"It's a little unusual for everyone to be on the same page," said Justin Hayes, program director at Idaho Conservation League. "It's not just environmentalists saying this, it's sort of like all the various constituencies have concerns because everyone has something on the line."

Hayes said his organization is in full support of the efforts to remove wild pigs, including unlimited shooting and aerial gunning.

"Feral pigs are really destructive to the natural environment," he said. "We need to do everything we can to get rid of feral pigs in Idaho ... they need to be shot out of the state."