BRATTLEBORO -- The most invasive and destructive large mammal species in North America is on the move and is an increasing threat to states in the Northeast.

"We occasionally hear word of a wild boar in the state," said Mark Scott, wildlife director of the Vermont Fish & Wildlife Department.

A new national study is under way and will help to determine if free-ranging feral swine, which are already in New Hampshire, have crossed the river into Vermont.

"This funding will bolster Vermont's monitoring efforts on wild hogs," said Scott. "Working together, Wildlife Services, our department and the Agriculture Agency will now to be able to proactively educate and monitor for feral swine."

The initiative is aimed at preventing further spread of feral swine and to reduce their population, damage and associated disease risks to protect both human health and the health of domestic swine.

Mark Ellingwood, the chief of wildlife for New Hampshire Fish & Game said there are between 100 and 200 free-ranging feral swine in Sullivan, Grafton and Cheshire counties.

"The reason they are in that area is we have the 23,000-acre Corbin's Park," said Ellingwood.

Corbin's Park is a privately-owned hunting preserve in Croydon that was established by Austin Corbin, a self-made millionaire, in 1889.

"By all evidence, it appears to be the source of most of the Eurasian, or Russian, boar, which breached the fence in multiple incidents," said Ellingwood, adding the managers of Corbin's Park have been good partners with the state. "I would assume they can cross the river in the same way bear, deer and moose do. I suppose they have the capacity to do so."

Nationwide, feral swine annually cause an estimated $1.5 billion in damage and can destroy as much as 1,000 acres per hour. They prey upon white-tailed deer fawns, wild turkeys, grouse, woodcock, other ground nesting birds and their eggs, insects, frogs, and salamanders. Feral swine will also out-compete native wildlife for food, such as acorns and beechnuts which are important resources for Vermont wildlife.

Along with property and wildlife destruction, feral swine can threaten the health of people, livestock and pets by transmitting as many as 30 pathogens and 37 parasites. Of particular concern are Brucellosis, Pseudorabies, Leptospirosis and Trichinosis, which pose human and/or livestock health risks.

Feral swine come in many colors and shapes but are most often black or brown and weigh anywhere from 100 to 200 pounds. They leave behind unique signs, such as rooting, wallows and tree rubs, and have tracks similar to deer, although swine hoofs are rounder in overall shape and tend to be more splayed and blunt at the tips than deer tracks.

Scott Gilroy of the Blue Mountain Forest Association, which runs Corbin's Park, told Foster's Daily Democrat it would be impossible to estimate how many wild boar are in the park or have escaped from it over the years. He said he's heard of half a dozen or so being killed by hunters outside the park each winter.

"Obviously several of them have gotten out because we've found places where the fences have been cut (by poachers). I think this would qualify very much as a nuisance rather than a plague," he told Foster's.

In New Hampshire, the feral swine are considered free-ranging private property, equivalent to livestock that has escaped, and can't be taken without the permission of the owners of Corbin's Park, said Ellingwood.

"And an individual who chooses to take them needs a hunting license," he said. "However, we are not advocates for hog hunting. We don't want to give anyone the impetus to suggest that would be a good idea."

A hunting license is not needed if a feral pig is rooting through your garden in the backyard.

"In New Hampshire, people have the right to protect their personal private property from animal damage," said Ellingwood. "But the people who own them are responsible for the damages they do and they have been willing to accommodate. Corbin's Park has no desire to have any of those animals free of their facility."

If a feral pig is spotted in Vermont, it can be taken without permission, said Scott, but again, the hunter must have a license.

"They're not classified as a game animal or a protected species," said Scott. "They are free game for anybody that sees one."

However, he said, it's wise for a hunter to confirm what he or she is shooting at is in fact a feral pig, because if it is instead a domesticated pig that just happened to get loose, the hunter might have to pay the owner if he kills it.

Scott said sightings of feral swine in Vermont are few and far between.

"It is illegal to possess live wild hogs in the state," he said. "And we're hoping there are none in the state and it stays that way."

Ellingwood said the Russian boar mostly avoids human contact, but can be aggressive if pushed or cornered.

"They're not dangerous to humans if you exercise reasonable judgment."

He said the swine that have escaped from Corbin's Park are different in genetics from farm animals and the swine that are running rampant in the southwestern and central United States.

"The Russian boar is a wild species with wild roots, but the spotted feral pig is a wild domestic animal."

The spotted feral pigs that have proven to be a plague in the southwestern and central United States were pets that were either released by or escaped from their caretakers.

"There doesn't appear to be any change in the Russian boar status in New Hampshire as opposed to the millions of animals in the part of the country that is dealing with the purposeful release of swine," said Ellingwood. "We are a long way from there."

The USDA's Animal and Plant Health Inspection Service is the recommended resource for landowners who may be experiencing property and or agricultural damage. For more information, visit www.aphis.usda.gov/wildlife_damage/feral_swine/index.shtml.

To help officials determine if feral swine are present in Vermont, please report sightings and any information to Vermont Wildlife Services at 1-800-472-2437 via email to fwinformation@state.vt.us.

Bob Audette can be reached at raudette@reformer.com, or at 802-254-2311, ext. 160. Follow Bob on Twitter @audette.reformer.