Feral Pig Toxicants in Texas an Additional Control Technique

TEXAS WILDLIFE BORDERLANDS NEWS

BORDERLANDS RESEARCH INSTITUTE FOR NATURAL RESOURCE MANAGEMENT

Feral Pig Toxicants in Texas An Additional Control Technique

Article by GRANT S. LAWRENCE, JUSTIN A. FOSTER, JOHN C. KINSEY, and RYAN S. LUNA

n contrast to public opinion, used for decades to mitigate damage in currently no registered feral pig toxicants hunting alone is not able to keep the cases of extreme economic loss and high in the U.S. feral pig population in check. pig densities. Toxicant campaigns are For this reason several state, federal and IIn order to maintain a stable population commonly referred to as the most cost international agencies have partnered to level, more than 70 percent removal rate is efficient feral pig control technique in investigate alternative control techniques required annually. Small local populations practice. Toxicants can be deployed in a for feral pigs. This collaborative effort of feral pigs have been effectively large variety of environments and have includes Texas Parks and Wildlife controlled with a combination of current shown to be 11 times less expensive than Department, USDA National Wildlife control methods such as trapping, snares, shooting and 80 times less expensive than Research Center, Animal Control fencing, dog hunting, precision shooting trapping. Technologies Australia, Connovation and aerial shooting. Introducing a safe and cost-effective Ltd. and USDA-APHIS-Wildlife Services- When compared to the statewide feral pig control measure in the U.S. will Texas. This partnership, along with help population expansion, all current control directly benefit natural resource managers from Borderlands Research Institute, methods combined continue to fall short by decreasing monetary expenses has identified a feral pig toxicant that is of the 70 percent removal threshold. associated with protecting their natural producing promising results. AgriLife Extension estimates our current resources. Although toxicants have shown Sodium nitrite is a salt most commonly annual removal rate around 29 percent. potential to be an efficient, inexpensive, used as a food preservative in cured meats With this in mind, exploration into multi-regional management tool, there are for human consumption and is found alternative population control methods has become necessary. Texas is in need of additional control methods for feral pigs, especially one adapted for urban deployment in extensive damage scenarios. Unlike private lands, where a variety of control techniques can be implemented, state agencies and private organizations lack the necessary tools to control problematic feral pig populations in urban settings. A potential solution to this problem has surfaced in the southern hemisphere. In Australia, toxicants have been

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40 TEXAS WILDLIFE NOVEMBER 2016 BORDERLANDS NEWS

naturally in several vegetable species. would be illegal, unethical and ineffective Ironically the compound that preserves as sodium nitrite’s salty taste is highly bacon and sausage is the same agent that aversive to pigs. proves lethal to feral pigs. After years of research and development, Sodium nitrite was selected as a potential researchers have identified a method of ‘Achilles heel’ toxicant by exploiting a stabilizing sodium nitrite in an oral bait unique weakness in the blood cells of feral that is highly lethal to pigs. Recently, pigs. Simply stated, the mode of action two formulations have become eligible reduces the blood’s ability to carry oxygen for registration with the Environmental until the animal expires. This lack of Protection Agency. Both formulations oxygen transportation causes the animal recorded 90.5 percent and 96.8 percent to fall unconscious and ultimately perish. mortality rate in pen trials, exceeding the Sodium nitrite was selected because it EPA’s minimal mortality requirement of is highly lethal to feral pigs and causes 90 percent. mortality in a humane fashion. Unlike With these promising pen trial results, other toxicants that can cause pain and the partnership has moved forward into suffering to the animal for as long as 5 – 31 the EPA registration process with the best days until mortality occurs, sodium nitrite performing candidate formulation. The is an acute toxin that produces a rapid, product is currently under review with an humane death usually within 1 – 3 hours. estimated final approval for field testing Feral pigs are a highly adaptable species Sodium nitrite also exhibits a short by late 2017. Researchers are optimistic capable of thriving in a variety of habitats. persistence time in the soil given it about the stringent EPA registration Feral pig sightings have now been naturally occurs in the nitrogen cycle process given that New Zealand recently verified in 253 Texas counties. The and assists in plant development. Sodium registered sodium nitrite as the first new presence of feral pigs comes at a high price nitrite is recorded for staying in soil mammalian pest toxin in the world in over as they cause an estimated at $1.5 billion for only 12 hours as opposed to some 30 years. Concurrently, our Australian in national damages annually. One-third synthetic rat poisons that can persist in partners are also in the stages of registry of this damage is reported in Texas, as the environment for up to 24 months. To with their respective environmental feral pigs account for $500 million in ensure environmental safety, additional agencies. damages annually with over $52 million testing is currently underway with Once U.S. registration is completed, agricultural losses alone. In addition to collaborative research on sensitivity to toxicant deployment will primarily causing agricultural and natural resource sodium nitrite dosed pig carcasses on be used by permitted applicators losses, the physical damage of feral pigs scavenging species such as coyotes and after receiving proper training and includes destruction to vehicles, urban and vultures to assess the potential risks to certification. Application of a toxicant suburban landscapes, vineyards, orchards, secondary consumers. will only be deployed in union with a archaeological sites, soils, fences and Feral pig toxicology research has specialized delivery system that only ranch infrastructure. AgriLife Extension reached new milestones within the past allows feral pigs to assess the bait. Several has estimated feral pig damage at about decade. The Feral Swine Research Facility, pig-specific feeding devices have been $7,500/landowner in annual losses. located at the Kerr Wildlife Management developed by independent companies; Without proper human intervention, Area in Hunt, Texas, has served as ground however, the partnership continues to native ecosystems will continue to suffer if zero for feral pig toxicants in the Lone investigate appropriate designs. we fail to mitigate the damages associated Star state. Since the program’s start in In spite of their perceived benefit as a with feral pigs. Toxicants can be a useful 2008, sodium nitrite has remained the hunting species, the presence of feral pigs tool for unique scenarios when traditional focal toxin with the majority of research comes at a high cost to Texas landowners control methods are not applicable, but efforts concentrated on increasing bait and natural resources alike. They are one they are not the final answer to the feral palatability and lethality, product stability, of the most ecologically destructive species pig epidemic. Public education, use of and minimizing risks to non-target species in North America and are expanding contemporary methods and regulation and secondary consumers. across the U.S. at alarming rates. Current remain critical. In its raw form sodium nitrite is unstable U.S. population estimates of feral pigs Feral pigs are well established in Texas and unpalatable to pigs. Discovering a bait are over 5 million with approximately 2.6 and appear to be here for the long haul. As matrix that masks the taste of sodium million pigs residing in Texas. responsible wildlife managers, we need to nitrite and pigs will readily consume has Feral pig populations increase use all available control techniques at our proven difficult and taxing. It is important rapidly because they possess the greatest disposal to keep the population in check to state that any attempt of private use reproductive potential of all free-ranging, for the benefit of our native ecosystems of sodium nitrite for feral pig control large mammal species in North America. and wildlife.