Field testing of a new feral hog control method experienced a major setback recently after hundreds of birds were found dead.
During a regular agricultural extension report to Wichita County Commissioners, extension agent David Graf reported the issue at a study underway in an undisclosed North Texas location.
Hog-Gone, with active ingredient sodium nitrite, was thought to be the next great hope for feral hog control.
Feral hogs, a non-native animal, can breed rapidly and cause major damage to crops.
Control methods such as fencing or hunting the hogs have proven inadequate to stem the influx of animals.
Commissioners noted hog sightings are on the rise, and they are increasingly becoming and urban, as well as country, issue.
The creatures can tear up backyards and athletic fields, can consume small pets and could be a danger to children and adults.
During a study with hog-activated feeders containing the poison, researchers found that hundreds of dead birds nearby had ingest the poisoned bait.
The product is expected to be a better alternative to the previously tested hog poison containing warfarin – a blood thinning agent.
Sodium nitrite is a product often used for preserving meats. When eaten in large doses over a short period of time, it is toxic to feral swine.
Justin Foster, Texas Parks and Wildlife Research Coordinator for Region 2, said he has been conducting research on feral hogs for more than 10 years, and has never seen a bird kill of this magnitude.
Researchers test poison on free-range hogs
“The Environmental Protection Agency-testing permitted field evaluation was the first use of sodium nitrite as a feral swine toxicant on free-range hogs,” he said Monday morning.
The testing is necessary for the United States Department of Agriculture to gain EPA experimental-use permitting (EUP) for the Hog-Gone product.
The USDA Wildlife Services reports there are more than six million feral swine in at least 35 states. They cause an estimated $190 million in damage each year.
During research, Foster said, concern focused on keeping deer, raccoons and other animals out of the poison-laced feeder system and ensuring the safety of animals who may feed off the poisoned hogs.
The study found success in keeping most non-target animals out of the feeder and they also showed animals who feed off the carcasses of hogs who ingest Hog-Gone were not negatively impacted.
This study was the first time sodium nitrite was delivered on free-range hogs with a feeder system.
The research team paired with scientists in Australia, who have previously tested sodium nitrite for hog control.
How the feeder system works
Foster said the current form of product is a very dense paste, that is scooped from a container.
To see if the hogs will eat the poisoned bait from a secured feeder is a lengthy testing process, Foster said.
First, the hogs are fed an inert attractant bait out of the feeder system with the doors of the feeder left open.
Then, the feeder doors are shut to see if the hogs can work the levers to feed themselves.
Next, the testing transitions to the toxic product, using a placebo version of the Hog-Gone.
“Then we have the pigs there who have learned how to feed and are consuming the nontoxic bait – it’s a couple-week process,” Foster said.
The researchers finally slip in the toxic version of bait into the closed feeder system that the hogs activate.
“We found the feeders worked very well. We did not have any breaches of feeders by non-target animals,” he said.
Issue didn't come from feeder breach
The concern came, he said, when they noticed some poisoned bait was dropped outside the feeder after the hogs ate.
Small, grain-eating grassland birds ate the poisoned bait and at least 200 birds died, according to Foster.
“While the number of birds taken is within the tolerances described within the environmental assessment, it is not acceptable to us as wildlife biologists,” he said.
Upon discovering the bird deaths, the research team immediately began efforts to mitigate the bird losses and told the EPA, if they want to continue with the process, changes must be made.
“What we are doing now is going back to captive trials. We have an altered bait format that helps reduce the attraction of bait to birds,” Foster said.
“I’ve never seen such a take in any of the testing. Small, perching birds were never the concern,” Foster said.
A previous study had focused on how poisoned hog may affect turkey vultures or other carnivorous animals that feed on the flesh.
“We see a negligible risk of acute mortality from consuming hogs who ate sodium nitrite bait,” he said, “We view this as critical and important, however it is not the largest hurdle that this team or any other has undertaken. We have some options to discourage attraction or availability without impacting palatability or potency.”
Bird kill may delay project by a year
The bird kill is a setback to field testing, Foster said, and could throw the project timeline off schedule by a year.
The initial goal was to have the sodium nitrite bait registered for use with the EPA by 2020-21.
“You are limited by season and can only test in certain places and times to attract pigs. We may only get an opportunity one or two times a year,” he said.
Foster said the feral hog issue is a major concern, especially here in Texas where the hog population is growing exponentially.
The USDA Wildlife Service reports trapping and hunting are not adequate means of controlling the hog population because studies show at least 70 percent of the feral swine population would have to be removed each year to prevent population growth.
As hogs move into more densely populated areas, they are becoming a concern for everyone, not just farmers and ranchers.