Managing feral swine — the land-damaging, disease-carrying wild hogs that roam throughout the country — starts with good data, according to Nana Tian, a forest economics researcher for the Arkansas Forest Resources Center.

To serve as a baseline for feral swine damage assessments to private landowners and help guide management practices, the Arkansas Forest Resources Center in Monticello led a multi-state survey of 4,500 landowners to gauge economic damage to croplands, forestlands, pasturelands/livestock and their combinations.

"We know feral swine can cause a lot of damage, but it was a little surprising to see so many forest landowners reporting damage," said Tian, who is also an assistant professor of forest economics in the College of Forestry, Agriculture and Natural Resources at the University of Arkansas at Monticello.

Tian noted that forest landowners usually do not monitor their forestland as regularly as cropland owners, but many forest landowners reported damage and were aware of the seriousness of feral swine damage.

The Arkansas Forest Resources Center is a partnership between the University of Arkansas System Division of Agriculture and the University of Arkansas at Monticello. Research is administered through the Division of Agriculture's Arkansas Agricultural Experiment Station.

The recently published survey estimates feral swine damages over five years across all of Arkansas and Louisiana and 38 counties in east Texas.

The average amount of land owned by those surveyed was 200 acres. Forestland and timberland losses were estimated at $17 per acre in both Arkansas and Louisiana, and $12 per acre in east Texas for the five-year period.

"We wanted to understand more about what was happening to the small landowners because smaller landowners may face more limitations than larger landowners in technical and financial assistance," Tian said. "We wanted to have more information from their side."

Common swine damage to forest landowners includes girdling trees through rubbing and damaging roots by rooting and chewing. In the southern U.S., feral swine are also known to root up newly planted tree seedlings in plantations of both pines and hardwood species. Tian said they can severely affect trees and timber resources.

Feral swine have rooted, wallowed and chomped their way into the ranks of America's invasive species, causing an estimated $1.5 billion in economic damages annually across the United States, according to the USDA's Animal and Plant Health Inspection Service. The Arkansas Department of Agriculture estimates feral hogs cause about $19 million in damage in Arkansas annually.

Soybean, corn and rice fields are a buffet table for a sounder of swine — the social unit of feral hogs. One sounder can root up a pasture overnight. Larger swine can kill and eat newborn calves and vulnerable cows. Feral swine teach their young how to evade traps and can trick even the most seasoned hunters and trappers. They are a problem for ranchers, farmers and even golf course and cemetery managers, said Becky McPeake, extension wildlife specialist with the University of Arkansas System Division of Agriculture.

McPeake serves on the Arkansas Department of Agriculture's Feral Hog Eradication Task Force, which is a group of state and partner agencies dedicated to managing Arkansas' feral swine problem.

There are more than 6 million feral swine in 35 states across the nation, including Hawaii, according to the USDA. Most of the swine population was established in southern states, first introduced in Texas by early Spanish explorers over 300 years ago as a source of cured meat and lard for settlers, the report noted. Regarded as an invasive species, feral swine are in all 75 counties of Arkansas with a population of about 200,000.

According to the Arkansas Department of Agriculture's Feral Hog Task Force, diseases of highest concern with feral swine include pseudorabies virus, swine brucellosis, swine influenza, African swine fever, classic swine fever and food and mouth disease.

Caution is given to hunters who harvest feral pigs, McPeake said, because swine brucellosis can infect people. Pseudorabies doesn't harm people but can be deadly if infected meat is fed to hunting dogs. The other diseases listed are of "great concern to swine producers and the agriculture industry because of untold expense should it ever get into domestic pigs," McPeake added.

Survey results
The feral swine economic impact survey was conducted in 2021 and published in January 2023. The project was initiated by Tian with research partners Jianbang Gan, professor in the department of ecology and conservation biology at Texas A&M University's College of Agriculture and Life Sciences; and Gordon Holley, professor in the School of Agricultural Sciences and Forestry at Louisiana Tech University.

The researchers obtained 361 survey responses from Arkansas, 319 from Louisiana and 226 from east Texas for an average valid response rate of 22.9% for the three states combined.

In addition to the forestland estimates, the survey estimates that landowners' average agricultural cropland damage in the past five years was $28 per acre in both Arkansas and Louisiana and approximately $25 per acre in east Texas. The most reported feral swine damage to agricultural crops was to corn, soybeans, rice, wheat, hay, silage and forage crops.

The reported damage to pastureland was very similar in all three states at $11 per acre.

Broader and deeper understanding
The 2021 survey provides a "broader and deeper understanding" of rural landowners' perceptions of feral swine damage, which can inform regionwide control measures, the report states. The work also provides nsights for understanding feral swine damage in the region and could be used to inform future incentive-based policies for encouraging landowners to actively manage or control this invasive pest, Tian said.

"This collaborative research enables us to understand a common issue faced by forest and agricultural landowners in Arkansas, East Texas and Louisiana," Gan said. "Such an understanding will aid in designing and implementing more effective management strategies for feral swine, a mobile invasive species, across the region."

"Feral swine control methods for individual landowners are not working at scale because of their fast breeding rates and mobility," Holley said. "It has to be a collective effort to keep their populations in check, and the data from this study is imperative to show the importance of wide scale control needs."

"Economic results can be used to justify the need for continued control efforts," McPeake said. "Despite our best efforts at collecting data, there are a number of damages which are more difficult to collect."

For example, McPeake said a farmer has described how feral hogs rooted up the polypipe for his irrigation system. It didn't damage the pipe but moved it so much the farmer had to pull laborers away from their time-sensitive tasks to realign the pipe.

Because of the uncertainty, economic assessments are typically conservative, but still useful for demonstrating damages and convincing funders of the necessity of continued removal efforts and possibly research, McPeake said.

"Even with that, we miss economics in their destruction of wildlife habitat," McPeake said. "The USDA has damage reports for crops, and they do an excellent job at getting that data about feral hogs, so we have a pretty good handle on their crop damages, but feral hogs cause a lot more than just crop damages. They cause all kinds of damage to the landscape and wildlife ecology."

The Arkansas Forest Resources Center study points out that feral swine eat ground-nesting birds and their eggs, threaten nesting success of rare birds like the lesser prairie chicken and reduce the population of game species such as deer. Their wallowing and bodily wastes also impact water quality and aquatic biota.

"Overall, feral swine can cause a variety of damages to natural ecosystems including habitat degradation and predation on, and competition, with native species," the report states.

The researchers' article, "Assessing feral swine damage in the western gulf region of Arkansas, Louisiana, and Texas," was published in the Biological Invasions journal in January.