State OKs toxin for war against feral hogs
Texas is letting slip the dogs of chemical warfare in its long-running and, so far, losing battle against a horde of as many as 3 million feral hogs that are wreaking environmental, ecological and economic havoc across the state.
That escalation is triggering skirmishes over questions of possible collateral damage to native wildlife sharing the landscape with the invasive swine and concerns about possible effects on hundreds of thousands of Texans who annually shoot or trap, then butcher and eat, more than 750,000 feral hogs killed in Texas.
At a Feb. 21 news conference in Austin, Texas Agriculture Commissioner Sid Miller announced the agency had issued a rule that would allow Kaput Feral Hog Bait, a pesticide containing the anticoagulant warfarin as its active ingredient, to be used in the control of feral hogs. The emergency rule, issued Feb. 6, makes Texas the first and, so far, only state to adopt regulations allowing the use of a lethal toxicant — poison — to control the invasive swine. Miller takes aim
Miller, who as a member of the Texas Legislature in 2011 sponsored a successful bill allowing aerial gunning of feral hogs by private citizens with the permission of landowners, trumpeted the new rule as a significant advance in the state’s ongoing war against feral hogs, which compete with native wildlife, carry and transmit diseases such as brucellosis, and annually cause tens of millions of dollars in damage to property, including an estimated $50 million in annual losses to agriculture.
“I am pleased to announce that the ‘feral hog apocalypse’ may be within Texans’ reach with the introduction of Kaput’s hog lure,” Miller said.
Miller’s action was made possible by the U.S. Environmental Protection Agency’s conditional registration last month of Kaput Feral Hog Bait under the federal statutes governing pesticide use across the country. Kaput, the brand name of pesticides produced by Colorado-based Scimetrics Ltd. Corp., is the first and, so far, only toxicant approved by federal authorities for use in feralhog control.
Warfarin, laced in prepared baits designed to be eaten by feral hogs, is toxic to pigs in the same way that it is lethal to rats, mice and other rodents for which the substance has been used as a toxicant for more than 60 years. Warfarin has therapeutic uses — it is one of the most common medications taken by humans as a blood-clot preventive. But ingested in sufficient quantities by some mammals, warfarin triggers fatal internal hemorrhaging
Warfarin’s effects are anything but therapeutic in pigs. Feral hogs’ physiology makes them susceptible to warfarin’s toxic effects at a much lower dose than almost any other animal, research has shown. The percentage of warfarin the Kaput Feral Hog Bait approved by EPA is 0.005 percent by weight — five times lower than the 0.025 percent warfarin by weight used in rats/mice baits.
The poison has proven very effective at killing feral hogs, according to research conducted in Texas by Genesis Labs, a sister company of Scimetrics.
As part of the 12-year process of developing and gaining EPA approval for Kaput Feral Hog Bait, the developers, operating under a federally issued experimental-use permit and in cooperation with Texas Department of Agriculture, conducted field trials of the toxinlaced baits and the feeder/ bait dispenser designed to allow feral hogs to access the bait but prevent access by other wildlife such as deer.
The month-long trials were conducted in the Texas Panhandle and involved monitoring of feral hogs and bait dispensers through radio tracking and trail-camera images. Research indicated the efficacy of EPA-approved baits was between 97.8 and 100 percent.
If a feral hog eats enough of the toxic bait, it dies. The toxin is relatively slow-acting, however. Hogs must regularly ingest the poisoned baits over multiple days for it to have a lethal effect.
Risk to non-target species that might ingest the warfarin-laced baits are low, available research, Scimetrics and Texas Department of Agriculture say. With the low level of warfarin in the Kaput baits, non-target wildlife would have to ingest impossibly large quantities to suffer acute toxic effects. As part of the 2015 field test, researchers conducted 97 searches of the test area during and after the month-long in an effort to locate any non-target victims of the toxic baits. They reported finding none, concluding, “The low warfarin concentrate bait proved effective in eliminating wild hogs while posing minimal exposure to nontarget wildlife.” Special feeder required
But to limit exposure of non-target species such as deer, raccoons, birds and other that might ingest the baits, protocols for distributing it mandate use of a specially designed feeder with a heavy “guillotine” door that must be lifted to access the bait. Feral hogs have little trouble using their stout snouts to lift the door, while the door’s weight and mode of operation stymies most other wildlife.
Additionally, use of the pig poison in Texas will be restricted. Under the rule change announced by Miller, the warfarinbased bait is classified as a “state-limited-use pesticide,” and it can be purchased and used only by state-licensed pesticide applicators.
Landowners or others who want to use the hog toxicant on property in Texas and who do not hold the required license will have to hire a licensed applicator to legally set up the approved bait dispensers and distribute the bait. That almost certainly will limit its use.
Some Texans would rather it not be used at all.
In the wake of Miller’s announcement, the Texas Hog Hunters Association initiated an online petition to have the rule revoked. The group cites concerns about the potential human health effects of eating feral hogs that have ingested the warfarin-infused baits as well as questions about collateral damage to non-target species such as deer or domestic dogs that ingest treated baits and possible secondary poisoning of animals and protected birds such as hawks and eagles.
As of early Saturday, the online petition at change.org had garnered 10,400 supporters.
Texas Department of Agriculture statements counter those concerns, noting the low levels of warfarin in hogs that consume the baits pose little threat to humans, espe- cially if they avoid eating the animal’s liver, where most of the warfarin will be concentrated. Also, the bait contains a blue dye that transfers that color to the fatty tissues of hogs. Hunters taking a hog and finding blue-tinted fat can decline to eat the animal. Detractors urge caution
The agency downplays the risk to non-target animals and scavengers, citing multiple studies indicating little or no risk to avian life and minimal risk to other animals. Natural high tolerance to the substance and low levels in bait-consuming hogs make it almost impossible for non-target species to consume enough of the bait or a warfarinpoisoned pig to have any acute effect.
Those leery of the assurances that the warfarin-laced baits pose no risks point to a resolution passed earlier this month by the Louisiana Wildlife and Fisheries Commission recommending “adequate evaluation of the feral hog toxicant Kaput and any other similar poisons prior to state approval to determine impacts on wildlife.” The Louisiana officials particularly noted concerns about possible effects on the state’s protected black bears, which can easily access the bait feeder/dispensers. Texas has bears, too.
Texas Parks and Wildlife Department, which was alerted by Agriculture Department of the decision to issue the rule change, has taken no position on the issue. But it is clear the agency charged with managing the state’s wildlife resources is not opposed to the idea of employing toxicants in the war against feral hogs. The agency has a long-running program to develop a feral-hog toxicant with sodium nitrite as its active ingredient and a specialized feeder to dispense the bait while limiting access by nontarget species.
Results from tests of the sodium nitrite baits and feeder, headquartered on TPWD’s Kerr Wildlife Management Area, have been encouraging, with the sodium nitrite toxin typically lethal to pigs within two hours of their ingesting it. But agency staff say EPA approval of the toxin is at least two years away.
In the meantime, warfarin-based pig poison has become one of the tools in the arsenal used to battle the state’s feral hog infestation — an arsenal that already includes the ability to hunt or trap unlimited numbers of feral hogs year round, day and night and even gun them from helicopters. And still, Texas’ feralhog population and the damage they do continues unabated.
There is no guarantee that allowing the use of pesticides will turn that tide, but it certainly has raised the stakes.