Research looks at another tool against pigs

Published on Saturday, 5 July 2014 22:34 - Written by Steve Knight

Pest or game species? That is part of the dilemma facing those trying to figure out what to do about wild pigs that are quickly becoming not just an American problem, but a North America.

To most landowners and biologists wild pigs are a pest. To others they are a reliable and lucrative source of income.

Causing tens of millions of dollars in agriculture losses in Texas alone, efforts continue to, if not eliminate wild pigs, to at least control them. Hunting hasn’t work. Nor has trapping or shooting them from helicopters.

Now comes chemical warfare in the form of something as simple as, ironically, the thing used to preserve bacon and ham, sodium nitrite.

Texas Parks and Wildlife Department is at the forefront of research into sodium nitrite in the United States. After five years of controlled testing in pens are the Kerr Wildlife Management Area the agency may be just a year or so away from seeing experimentation on a much larger scale.

The idea of using sodium nitrite began in Australia where wild pigs have been a problem longer than they have here. TPWD has teamed with Animal Control Technologies, the lead researcher in Australian, the National Wildlife Research Center in Colorado and the Texas Department of Agriculture to develop protocol and studies here.

Don Frels Jr., TPWD project coordinator said the department originally got involved in the research to determine sodium nitrite’s impact on non-targeted species such as white-tailed deer, raccoons and birds. That involvement evolved into more.

Sodium nitrite is a simple solution with a lot of intricate details, all of which haven’t been worked out yet.

“The way it acts is that it inhibits the blood’s ability to carry oxygen. There is an enzyme that reverses that effect of it. We have (the enzyme), but pigs only have little of it,” Frels explained.

Because pigs have so little of the enzyme their system is slow to counter the effects of the sodium nitrite.

“We can take advantage of that slower system. They just becoming intoxicated, lethargic, lay down and go to sleep,” Frels said.

There is a problem, though.

“If they don’t get an overdose they can overcome it,” the biologist added.

The issue, Frels said, is that sodium nitrite to a wild pig is akin to alcohol to humans — everyone has a different tolerance level based on a wide-ranging number of factors, including size, the last time they ate and how fast the consume it.

He said what works best is when a sounder of pigs runs up to a feeder and goes into a feeding frenzy.

Unfortunately it doesn’t always work that way.

“There is a lot of social behavior in a sounder of pigs. They are very social creatures and hierarchy is very important. Say a big sow comes in and eats, feels lethargic and wanders off and doesn’t allow any of the other to eat. You just killed her,” Frels said.

Frels said another issue researchers are trying to overcome is sodium nitrite itself. It is unstable off the shelf, changing color, losing potency and emitting a pungent odor when subjected to moisture.

“Contrary to what people think, pigs can become particular eaters,” he said.

The cost quickly goes up when encapsulating sodium nitrite to protect it from the weather. That is where the research is at this point, finding the right substance to encapsulate it in and in the right size.

The problem is being worked on, and the research has shown as much as a 90 percent kill success rate in some trials, the level the U.S. Environmental Protection Agency is going to require to allow larger scale testing.

TPWD continues to look at sodium nitrite’s effect on wildlife. Frels said one of the biggest concerns is with vultures, which is one of the few species that will eat the stomach of a dead pig. He explained sodium nitrite will remain in the pigs stomach after it dies.

Another worry is bears.

“Bears are hard to come by for research. We are not sure how susceptible they are to sodium nitrite, but we know they are good at getting into feeders,” Frels said.

While most mammals are prone to be susceptible to sodium nitrite, Frels doesn’t think white-tailed deer would normally eat enough to be affected.

If all the issues are overcome and sodium nitrite is approved for landowner use, Frels said it isn’t going to completely rid the state of its 3-million-plus wild pigs.

“The way we look at this is it is another tool in tool box for landowners. We don’t think it is the final answer all by itself, but in some cases it could be very successful. Ideally we want a pellet-based toxicant you can buy at the store, put in hog feeder for several weeks and they will eat it and go off and die,” Frels said.

The research has shown enough promise that those involved see light at the end of the tunnel.

“We are leaps and bounds from where we started. We have come a long way and are still in this game. If we thought we were not going to get to the final stage, we wouldn’t still be in it,” Frels said.