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A sounder of hogs grazes under trees

Researchers hope popular pigs provide key to controlling feral hogs

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If you see one pig, there’s bound to be more nearby.

That’s the premise behind a novel method of controlling feral hogs now being tested by researchers at the University of Georgia. Called the “Judas pig technique,” the study is the first test in 15 years of its effectiveness against the invasive animals, which cause billions of dollars in crop damage each year.

“It targets social animals—you capture one, put a (GPS) collar on it, let it go, and you know it’s going to find more of its kind,” said Faith Kruis, a master’s student at the UGA Warnell School of Forestry and Natural Resources who has been tracking feral hogs in Southwest Georgia for the past year. “Since you have a collar on that individual, you can find that one and remove the others it’s with, then let that same one jump to another group of individuals, and it keeps going.”

A pig fitted with a GPS collar around its neck
A pig that has been fitted with a GPS collar.

While the technique has been studied among feral goats, little is known about its effectiveness with hogs—especially in places such as Southwest Georgia, where their numbers have swelled to create costly issues for landowners. Kruis aims to help identify the best characteristics to look for in a Judas pig, as well as the types of landscapes the pigs prefer throughout the year.

To do this, Kruis works with wildlife services professionals with the U.S. Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) who began removing hogs in the area since 2020, through the same grant funding Kruis’ study. When a sounder of hogs is caught, she identifies a potential Judas—male or female sub adult between 60 and 90 pounds—to fit with a GPS collar. 

Then, while the rest of the sounder is removed, the lone pig is released and tracked until it finds another group of feral hogs.

Traditional whole-sounder removal involves baiting an area that shows signs of hog presence, leaving the bait until the targeted hogs are seen on a nearby camera, then slowly building a circular trap. After the trap is built and the hogs are comfortable coming inside the area to feed, the sides are released remotely, trapping all the pigs for removal.

A method to identify a Judas pig would help landowners and wildlife specialists be more efficient with future removals, allowing the pig to do the work of locating the others. Ideally, said Kruis, the information she gathers from the project can help increase the efficiency of trapping and removing the animals in the future.

For now, she said, the tricky part of the process is identifying when the Judas pig finds a new group. By following its movements with the GPS collar, she can see when it frequents a particular area. Then, she sets up wildlife cameras to verify it’s with more pigs, and the process starts all over again. 

A black-and-white image of pigs caught on camera at night
Pigs caught on a wildlife camera at night.

“So, from week to week, I’m looking at all the positions and seeing if they move and start frequenting different spots, then getting pictures of that spot,” she said. “Sometimes they’re very predictable, but then others are very unpredictable. I’m constantly moving the camera and trying to get it on camera, because that’s how I have evidence it’s with others.”

So far, Kruis has data from 13 pigs and is aiming for about 11 more before data collection wraps up in May. The study will be the first of its kind to investigate the method using a large sample of feral hogs. 

Her project is part of a grant for the Georgia Albany Feral Swine Control Project awarded to the Flint River Soil and Water Conservation District. It’s part of the Feral Swine Eradication and control Pilot Program that was established by the 2018 Farm Bill.

She and another graduate student, Justine Smith, are also evaluating the places feral hogs frequent and the amount of damage they do. By the end of the study, they will have foundational information on, for example, the types of vegetation the animals prefer during different times of the year, the amount of damage they do to agricultural fields and whether they come back to certain areas year after year.

Smith’s work involves using drones to identify and map damage done by the animals over time. Her portion of the study will identify patterns in their damage and which types of agricultural areas they frequent. Kruis’ data will evaluate the types of vegetation feral hogs frequent at different times of the day throughout the year.

Their information will be a first for the United States, particularly in agricultural areas.

“For example, are they in corn fields all day when it’s hot, or when it’s cooler out? Where are they at night versus the day, and how do crops influence that?” said Kruis. Previous studies have inferred overall trends in areas with agriculture, she added, “but it’s always been through large-scale data sets and not a smaller area honing in on specific pigs.”
 

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