Wild Pig Populations Research Articles

Comparing efficiencies of population control methods for responding to introductions of transboundary animal diseases in wild pigs

Introductions of transboundary animal diseases (TADs) into free-ranging wildlife can be difficult to control and devastating for domestic livestock trade. Combating a new TAD introduction in wildlife with an emergency response requires quickly limiting spread of the disease by intensely removing wild animals within a contiguous area. In the case of African swine fever virus (ASFv) in wild pigs (Sus scrofa), which has been spreading in many regions of the world, there is little information on the time- and cost-efficiency of methods for intensively and consistently culling wild pigs and recovering carcasses in an emergency response scenario. We compared the efficiencies of aerial operations, trapping, experimental toxic baiting, and ground shooting in northcentral Texas, USA during two months in 2023. Culling and recovering carcasses of wild pigs averaged a rate of 0.15 wild pigs/person hour and cost an average of $233.04/wild pig ($USD 2023) across all four methods. Aerial operations required the greatest initial investment but subsequently was the most time- and cost-efficient, costing an average of $7266 to reduce the population by a standard measure of 10 %, including recovering carcasses. Aerial operations required a ground crew of ∼7 people/helicopter to recover carcasses. Costs for reducing the population of wild pigs using trapping were similar, although took 13.5 times longer to accomplish. In cases where carcass recovery and disposal are needed (e.g., response to ASFv), a benefit of trapping was immediate carcass recovery. Toxic baiting was less efficient because both culling and carcass recovery required substantial time. We culled very few wild pigs with ground shooting in this landscape. Our results provide insight on the efficiencies of each removal method. Strategically combining removal methods may increase overall efficiency. Overall, our findings inform the preparation of resources, personnel needs, and deployment readiness for TAD responses involving wild pigs.

Population response of eastern wild turkey to removal of wild pigs

AbstractThere is insufficient understanding of interspecific interactions with the eastern wild turkey (Meleagris gallopavo silvestris) and wild pigs (Sus scrofa). Wild pigs compete with wild turkeys and predate nests and adults; however, population‐level effects on wild turkeys are not clear. Using cameras, we assessed responses of wild turkey populations to wild pig removal in central Alabama, USA, from 2018–2021. We compared wild turkey relative abundance and occupancy on 3 large‐scale pig‐removal treatment sites (3,407–5,531 ha) relative to a control site (2,510 ha) during 1 pre‐treatment year and 2 post‐treatment years, with analyses including a covariate expressing the cumulative number of pigs removed from each site standardized by the initial pig abundance on the site. We removed 1,851 wild pigs from the 3 treatment sites over 22 months. Based on N‐mixture modeling, when the number of pigs removed was equal to our baseline population estimates (i.e., 100% removal relative to initial population), there were 1.50 (95% CL = 1.01–2.23) times as many wild turkeys, and detection of wild turkeys was 2.01 (95% CL = 1.49–2.70) times as likely. Additionally, poults were 3.49 (95% CL = 1.12–10.89) times as likely to occupy an area when the number of pigs removed was equal to our baseline population estimates compared with poult occupancy at baseline pig abundance. Our data suggests that reduction of wild pig populations may lead to a localized increase in populations of wild turkeys.

Agricultural and Ecological Resources Safeguarded by the Prevention of Wild Pig Population Expansion.

Wild pigs (Sus scrofa) are one of the most destructive invasive species in the US, known for causing extensive damage to agricultural commodities, natural resources, and property, and for transmitting diseases to livestock. Following the establishment of the National Feral Swine Damage Management Program (NFSDMP) in 2014, the expansion of wild pig populations has been successfully slowed. This paper combines two modeling approaches across eight separate models to characterize the expansion of wild pig populations in the absence of intervention by the NFSDMP and forecasts the value of a subset of resources safeguarded from the threat of wild pigs. The results indicate that if wild pigs had continued spreading at pre-program levels, they would have spread extensively across the US, with significant geographic variation across modeling scenarios. Further, by averting the threat of wild pigs, a substantial amount of crops, land, property, and livestock was safeguarded by the NFSDMP. Cumulatively, between 2014 and 2021, wild pig populations were prevented from spreading to an average of 724 counties and an average of USD 40.2 billion in field crops, pasture, grasses, and hay was safeguarded. The results demonstrate that intervention by the NFSDMP has delivered significant ecological and economic benefits that were not previously known.

Seroprevalence of Bovine Viral Diarrhea Virus in Wild Pigs (Sus scrofa) in 17 States in the USA.

Wild pigs (Sus scrofa) are among the most detrimental invasive species in the USA. They are damaging to crops and agriculture, pose a public health risk as reservoirs of zoonotic pathogens, and may also spread disease to livestock. One pathogen identified in wild pigs is bovine viral diarrhea virus (BVDV), a virus that causes an economically important disease of cattle (Bos taurus and Bos indicus). We sought to determine the BVDV seroprevalence in wild pigs in 17 states across the US and to determine whether age category, sex, or location were associated with a positive antibody titer. Serum samples from 945 wild pigs were collected from 17 US states. Virus neutralization assays were performed to determine antibody titers against BVDV-1b and BVDV-2a. Total BVDV seroprevalence for the study area was 5.8% (95% confidence interval [CI], 4.11-8.89). Seroprevalence across all evaluated states was determined to be 4.4% (95% CI, 2.48-6.82) for BVDV-1b and 3.6% (95% CI, 1.54-5.60) for BVDV-2a. The seroprevalence for individual states varied from 0% to 16.7%. There was no statistical difference in median antibody titer for BVDV-1b or BVDV-2a by sex or age category. State seroprevalences for both BVDV-1b and BVDV-2a were associated with wild pig population estimates for those states.

African Swine Fever in the Philippines: A Review on Surveillance, Prevention, and Control Strategies.

African swine fever (ASF), a highly contagious disease of swine, has posed a significant global threat to the swine industry. As an archipelago, the Philippines has a geographic advantage when it comes to the risk of ASF transmission. However, since its introduction to the Philippines in 2019, it has proliferated not only in backyard and commercial farms but also in wild pig populations. While certain parts of the country were more affected than others, the epidemiologic features of ASF necessitate that all affected areas must be closely monitored and that confirmed cases be treated with the utmost care. With the very limited data on ASF epidemiology and surveillance in the Philippines, future efforts to combat ASF must place even greater emphasis on improved prevention and control strategies. It is worth mentioning that the government's efforts toward comprehensive ASF surveillance and epidemiological investigation into the possible ASFV sources or transmission pathways are the most important measures in the prevention and control of ASF outbreaks. This review article provides a comprehensive overview of the current swine industry and ASF situation in the Philippines, which includes its epidemiology, surveillance, prevention, and control strategies.

Can hair snares provide a reliable method for estimating abundance of an exotic ungulate?

Mitigating exotic species invasions requires reliable information on abundance and source-sink dynamics to evaluate effectiveness of control efforts. Despite being present in the southeastern United States for centuries, wild pigs (Sus scrofa) continue to invade new areas, including the Sam D. Hamilton Noxubee National Wildlife Refuge (NNWR) in Mississippi, a forested landscape with an emerging wild pig population. Considering the early stage of invasion, we designed and implemented a non-invasive hair sampling technique to estimate abundance and relatedness of wild pigs within the NNWR. Following 8-week sampling periods in 2021 (n = 160 samples) and 2022 (n = 159 samples), we identified 38 and 26 unique individuals, respectively, although recapture rates were too low to yield precise abundance estimates. We also identified low heterozygosity indicating high relatedness among our population which likely reflected lack of barrier features to gene flow and/or a limited number of external source populations. Finally, we observed positive trends in viable samples collected relative to sampling week, suggesting more optimal sampling period(s) may exist (e.g., autumn). We also acknowledge that use of grain in more accessible areas rather than our remote approach using scent-only attractants may increase hair snare attractiveness and wild pig encounters, while permitting increased sampling frequency. Collectively, these modifications (i.e., altered season, bait type, and access) provide viable pathways to increase precision for abundance estimates. When used concomitantly with ongoing monitoring and control efforts, non-invasive hair sampling will contribute to a more holistic understanding of this exotic species and better inform management actions.

D for dominant: porcine circovirus 2d (PCV-2d) prevalence over other genotypes in wild boars and higher viral flows from domestic pigs in Italy.

Porcine circovirus 2 (PCV-2) is a key pathogen for the swine industry at a global level. Nine genotypes, differing in epidemiology and potentially virulence, emerged over time, with PCV-2a, -2b, and -2d being the most widespread and clinically relevant. Conversely, the distribution of minor genotypes appears geographically and temporally restricted, suggesting lower virulence and different epidemiological drivers. In 2022, PCV-2e, the most genetically and phenotypically divergent genotype, was identified in multiple rural farms in North-eastern Italy. Since rural pigs often have access to outdoor environment, the introduction from wild boars was investigated. Through a molecular and spatial approach, this study investigated the epidemiology and genetic diversity of PCV-2 in 122 wild boars across different provinces of North-eastern Italy. Molecular analysis revealed a high PCV-2 frequency (81.1%, 99/122), and classified the majority of strains as PCV-2d (96.3%, 78/81), with sporadic occurrences of PCV-2a (1.2%, 1/81) and PCV-2b (2.5%, 2/81) genotypes. A viral flow directed primarily from domestic pigs to wild boars was estimated by phylogenetic and phylodynamic analyses. These findings attested that the genotype replacement so far described only in the Italian domestic swine sector occurred also in wild boars. and suggested that the current heterogeneity of PCV-2d strains in Italian wild boars likely depends more on different introduction events from the domestic population rather than the presence of independent evolutionary pressures. While this might suggest PCV-2 circulation in wild boars having a marginal impact in the industrial sector, the sharing of PCV-2d strains across distinct wild populations, in absence of a consistent geographical pattern, suggests a complex interplay between domestic and wild pig populations, emphasizing the importance of improved biosecurity measures to mitigate the risk of pathogen transmission.

Comparative epidemiological study of the spread of African swine fever in Ukraine and some Eastern European countries

African swine fever is one of the most serious threats to the world pig industry due to high infectivity and mortality rates among pigs. To date, no effective means of active prevention of the infection have been developed. The only effective method of control is passive monitoring of the spread of the pathogen among the population of domestic and wild pigs, detection of infected animals and their depopulation. The study analyzes the spread of African swine fever in Ukraine from 2012 to 2024 and compares it with the countries that share a common border – Poland, Romania, Hungary, Slovakia and Moldova. In Ukraine, the first outbreaks were recorded in 2012 in Zaporizhzhia region among domestic pigs. In total, 619 outbreaks were detected during the study period: 482 among domestic pigs and 137 among wild pigs. The largest number of outbreaks was recorded in Odesa (64), Poltava (54), Mykolaiv (52) and Kyiv (46) regions. In Eastern European countries, African swine fever was detected later: in Poland – since 2014 (1304 among domestic and 17871 among wild pigs), Romania – since 2017 (6729 and 3649, respectively), Hungary and Slovakia – since 2018 (0 and 7875; 72 and 3645). In Moldova, the first outbreak was in 2020 (39 among domestic and 45 among wild pigs). The highest total number of outbreaks was recorded in Poland (19175), mainly among wild boars (93.2%). In Hungary, all detected cases involved wild animals. The analysis revealed a statistically significant difference in the number of African swine fever outbreaks between the analyzed countries. There is also a difference in the number of outbreaks within the analyzed time period. If we analyze the number of cases since 2018, there is no statistically significant difference. Prevention and control of African swine fever are complicated by the circulation of the pathogen among wild boars, non-compliance with biosecurity measures by owners of small pig farms and the movement of infected animals. Comprehensive monitoring with early detection of outbreaks and timely destruction of infected animals plays a key role. Key words: pigs, African swine fever, spread, viruses, epizootic analysis, epizootic situation.

Natural selection on feralization genes contributed to the invasive spread of wild pigs throughout the United States.

Despite a long presence in the contiguous United States (US), the distribution of invasive wild pigs (Sus scrofa × domesticus) has expanded rapidly since the 1980s, suggesting a more recent evolutionary shift towards greater invasiveness. Contemporary populations of wild pigs represent exoferal hybrid descendants of domestic pigs and European wild boar, with such hybridization expected to enrich genetic diversity and increase the adaptive potential of populations. Our objective was to characterize how genetic enrichment through hybridization increases the invasiveness of populations by identifying signals of selection and the ancestral origins of selected loci. Our study focused on invasive wild pigs within Great Smoky Mountains National Park, which represents a hybrid population descendent from the admixture of established populations of feral pigs and an introduction of European wild boar to North America. Accordingly, we genotyped 881 wild pigs with multiple high-density single-nucleotide polymorphism (SNP) arrays. We found 233 markers under putative selection spread over 79 regions across 16 out of 18 autosomes, which contained genes involved in traits affecting feralization. Among these, genes were found to be related to skull formation and neurogenesis, with two genes, TYRP1 and TYR, also encoding for crucial melanogenesis enzymes. The most common haplotypes associated with regions under selection for the Great Smoky Mountains population were also common among other populations throughout the region, indicating a key role of putatively selective variants in the fitness of invasive populations. Interestingly, many of these haplotypes were absent among European wild boar reference genotypes, indicating feralization through genetic adaptation.

Effects of ungulate‐proof fencing on space use by wild pigs

AbstractWild pigs (Sus scrofa) are a highly adaptable species that have invaded many regions and cause significant damage throughout the world. Ungulate‐proof fencing is increasingly used in conjunction with other control techniques to manage wild pig populations. However, little is known about how fencing affects wild pig space use behaviors and whether any changes may be exploited to increase efficacy of control activities. Our goal was to understand how wild pigs altered their space use behaviors in response to newly constructed fencing. Specifically, we examined for changes in space use area (home range and core area), increases in overlap with conspecifics, and shifts in space use as ungulate exclusion fencing was constructed on northern Guam from February 2021 to March 2022. Wild pigs closer to the fence had decreased space use. For every 200 m nearer newly constructed fence, home ranges and core areas decreased approximately 15% and 16%, respectively. When individual wild pigs were enclosed by the fence, those animals increased their home range overlap with conspecifics by approximately 76% compared to wild pigs outside the fence. Wild pigs shifted their home ranges 3 to 9 times more during the first part of fence construction when 68% of the fence was completed compared to all other time periods, with male wild pigs shifting greater distances than females by 1.15 times. The construction of ungulate fencing led to smaller space use areas of wild pigs on both sides of the fence and intensified use of the area inside the fence by wild pigs contained within (i.e., more overlap). Management activities nearer the fence should account for decreases in home range and core area size to maximize population control efforts (i.e., more densely spaced trap sites). Enclosed wild pigs should be eradicated quickly to minimize damages to sensitive flora and fauna and decrease disease risk from intensified movement behaviors inside the fence.

Perceptions of Wild Pig Impact, Management, and Policy in Alabama

Successful management of invasive species often requires working across public and private landownerships. A prime example of an invasive species that commonly occurs on privately and publicly owned and managed lands is the wild pig (Sus scrofa). Because of the multitude of negative impacts associated with wild pigs, management must occur across both private and public lands to achieve widespread control and sustained success. However, managing wild pigs across property boundaries is challenging as we know very little about differing management practices and landowner perspectives. To address this knowledge gap, we sought to understand wild pig management efforts on privately owned lands, the perceived economic, ecological, and human health impact of wild pigs, and beliefs related to policy. Generally, stakeholders believe wild pigs have negative impacts on wildlife, the economy, and ecological and public health, however less than half of landowners participate in wild pig control. Furthermore, stakeholders believe that the responsibility of managing and paying for damages associated with wild pigs lies with individual landowners. Our findings suggest that increased efficacy of wild pig control and collaboration between private and public landowners is not only possible but also necessary if wild pig population control is to be regionally successful.

Seasonal efficacy and risks from a sodium nitrite toxic bait for wild pigs.

Wild pigs (Sus scrofa) are an invasive and destructive species throughout many regions of the world. A sodium nitrite (SN) toxic bait is currently used in Australia and being developed for use in the US and other countries to combat the increasing populations of wild pigs. In the US, efforts to modify the Australian SN-toxic bait and baiting strategy have focused on reducing issues with non-target animals accessing the SN-toxic bait spilled outside of bait stations by wild pigs. We tested and compared modifications for efficacy (with wild pigs) and hazards (with non-targets) in north-central Texas, US during summer (July 2021) and winter (March 2023) seasons. During both seasons we found that visitation to the bait sites declined 94-99% after deploying the SN-toxic bait, and we found a total of 106 dead wild pigs, indicating considerable lethality for the local population. Prior to deploying the SN-toxic bait, Global Positioning System (GPS)-collared wild pigs were more likely to cease visiting bait sites during summer when foraging resources were abundant. Farrowing decreased visitation to bait sites during the winter. We observed no dead non-targets during summer; winter results showed an average of 5.2 dead migrating birds per bait site (primarily Dark-eye juncos [Junco hyemalis]) from consuming SN-toxic bait spilled by wild pigs. The presence and winter-foraging behaviors of migrating birds appeared to increase hazards for those species. The current formulation of SN-toxic bait was effective at removing wild pigs during both seasons, however it is clear that different baiting strategies may be required in winter when migrating birds are present. Baiting wild pigs prior to farrowing during the winter, and during drier summers, may further improve efficacy of the bait. Reducing hazards to non-targets could be achieved by refining the SN-toxic bait or modifying bait stations to decrease the potential for spillage, decreasing environmental persistence if spilled, or decreasing attractiveness to migrating birds. © 2024 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Comprehensive Economic Impacts of Wild Pigs on Producers of Six Crops in the South-Eastern US and California

Wild pigs (Sus scrofa) cause damage to agricultural crops in their native range as well as in the portions of the globe where they have been introduced. In the US, states with the highest introduced wild pig populations are Alabama, Arkansas, California, Florida, Georgia, Louisiana, Mississippi, Missouri, North Carolina, South Carolina, and Texas. The present study summarizes the first survey-based effort to value the full extent of wild pig damage to producers of six crops in these eleven US states. The survey was distributed by the USDA National Agricultural Statistical Service in the summer of 2022 to a sample of 11,495 producers of corn (Zea mays), soybeans (Glycine max), wheat (Triticum spp.), rice (Oryza sativa), peanuts (Arachis hypogaea), and sorghum (Sorghum bicolor) in these 11 states. Our findings suggest that the economic burden of wild pigs on producers of these crops is substantial and not limited to the direct and most identifiable categories of crop damage (i.e., production value lost due to depredation, trampling and rooting). We estimate that the annual cost to producers of these six crops in the surveyed states in 2021 was almost USD 700 million.

Rapid recovery of invasive wild pig (Sus scrofa) populations following density reduction

Trapping is an effective strategy for control of invasive wild pig (Sus scrofa), but eradication of populations via trapping alone typically is impractical throughout much of the species’ introduced range. Consequently, recovery of wild pig populations to pre-trapping levels following control is a major impediment to success of long-term control. In this study, we conducted camera-trap surveys to monitor recovery of two wild pig populations immediately following density reductions achieved via trapping on two sites on the Savannah River Site, SC. We used spatial capture-recapture models to estimate wild pig density during seven 3 week periods spanning 12 months to: (1) determine the time required for populations to recover to pre-trapping levels; and (2) evaluate trends in population growth, density, and distribution during recovery. Recovery of both wild pig populations started immediately after trapping ceased, with populations reaching pre-trapping levels in 3 and 5 months. Threeweek population growth rates for each wild pig population during recovery averaged 1.28 (range = 1.11–1.39 on site 1) and 1.24 (range = 0.64–1.92 on site 2), which corresponded to a 345% and 132% increase in abundance (an increase of 141 and 126 individual wild pigs on site 1 and 2, respectively) of each population by the last survey period. Rapid recovery and growth beyond pre-trapping levels of wild pig populations likely were driven by residual wild pigs not removed by trapping and compensatory reproduction and immigration. Our study is one of the first to provide information on how quickly wild pig populations can recover following overall density reductions of 54–68% and indicates practitioners should be prepared to reinitiate trapping efforts in as little as 3 months to prevent recovery of wild pig populations following control.

Prevalence of Astroviruses in Different Animal Species in Poland.

Astroviruses (AstVs) are small RNA viruses characterized by a high mutation rate, the ability to recombine, and interspecies transmission, which allows them to infect a multitude of hosts including humans, companion animals, and farmed animals as well as wildlife. AstVs are stable in the environment, and their transmission is usually through the fecal-oral route or via contaminated water and food. Although direct zoonotic transmission was not confirmed, interspecies transmission events have occurred or have been indicated to occur in the past between wild and domestic animals and humans. They cause large economic losses, mainly in the poultry sector, due to gastroenteritis and mortality. In young children, they are the second most common cause of diarrhea. This study involved 166 intestine samples and pools of spleen, lymph node, and kidney samples collected from 352 wild animals, 52 pigs, and 31 companion animals. Astroviruses were detected in the intestine samples and were separately detected in pools of tissue samples prepared for individual animals using a heminested RT-PCR protocol. Amplicons were subjected to Sanger sequencing, and a phylogenetic analysis of 320 nt RNA-dependent RNA polymerase (RdRp) fragments referring to known nt sequences of astroviruses was performed. Astroviral RNA was detected in the intestine samples and/or tissue pools of red foxes (nine positive intestines and six positive tissue pools), rats (two positive intestines and three positive tissue pools), a cat (one AstV detected in an intestine sample), pigs (eight positive tissue pools), and wild boars (two positive pools of spleens, kidneys, and lymph nodes). No astroviral RNA was detected in wild mustelids, dogs, or other small wild animals including rodents. A phylogenetic analysis revealed that the astroviruses detected during this study were mostly host-specific, such as porcine, canine, and rat astroviruses that were highly homologous to the sequences of reference strains. In one of two wild boars, an AstV distinct to porcine species was found with the highest nt identity to Avastroviruses, i.e., turkey astroviruses, which suggests potential cross-species transmission of the virus, as previously described. Here, we present the first detection of astroviruses in the population of wild animals, companion animals, and pigs in Poland, confirming that astroviruses are frequent pathogens circulating in animals in the field. Our study also suggests potential cross-species transmission of Avaastrovirus to wild boars; however, further molecular characterization is needed.

Distribution and prevalence of antibodies to Trichinella spp. and Toxoplasma gondii in wild pigs (Sus scrofa) in the United States

Invasive wild pigs (Sus scrofa) are a reservoir for over 100 viral, bacterial, and parasitic pathogens that are transmissible to humans, livestock, domestic animals, and wildlife in North America. Numerous historical local surveys and results from a nation-wide survey (2006–2010) indicated that wild pigs in the United States act as reservoirs for Trichinella spp. and Toxoplasma gondii, two zoonotic pathogens of importance for human and animal health. Since that time, wild pig populations have expanded and increased in density in many areas. Population expansion of wild pigs creates opportunities for the introduction of pathogens to new areas of the country, increasing health risks. The goal of this study was to investigate the current geographic distribution and prevalence of Trichinella spp. and T. gondii antibodies in wild pigs using serum samples collected from 2014 to 2020. Serum samples from 36 states were tested for antibodies to Trichinella spp. (n = 7467) and T. gondii (n = 5984) using commercially available enzyme-linked immunosorbent assays. Seroprevalence for Trichinella spp. (12.4%, 927/7467) and T. gondii (40.8%, 2444/5984) are significantly higher compared to a previous 2006–2010 study across all regions. Results from this study also showed a lower seroprevalence (4.8%) for Trichinella spp. in the West region compared to the other regions (South: 13.4%; Midwest: 18.4%; Northeast: 19.1%). There were new detection records for antibodies to Trichinella spp. in 11 states, mostly in the West, Midwest, and Northeast regions compared to a previous study in 2014. Males and juveniles were less likely to be positive for Trichinella spp. antibodies, compared to females and older animals, respectively. Seroprevalence was similar for T. gondii across the regions (31.8–56%) with some states having particularly high seroprevalence (e.g., Hawaii 79.4% and Pennsylvania 68%). There were new T. gondii antibody detection records for 12 states, mostly in the West, Midwest, and Northeast regions. Adults were more likely than juveniles and subadults to be seropositive. These data confirm that the distribution and prevalence of antibodies for Trichinella spp. and T. gondii are increasing in the United States, likely driven by wild pig population growth and range expansion.

Alabama agricultural producers’ experiences with wild pigs (Sus scrofa) and their preferences concerning wild pig management

ABSTRACT Government agencies and landowners use a variety of lethal methods to reduce invasive wild pig populations and resulting agricultural damages. To provide decision-makers with information regarding Alabama farmers’ experiences with wild pigs and their preferences for management actions, we surveyed Alabama Farmers Federation members in 2020. We found that wild pigs were commonly present on livestock, timber, and crop production acreage, but wild pig damages and costs were much more common among crop producers. Respondents’ wildlife acceptance capacity for wild pigs was low and all lethal control methods were considered acceptable by most respondents, particularly those performed by landowners. While there is likely a consensus among Alabama farmers that wild pig numbers need to be reduced within the state, managers should continue to build support by working closely with crop producers and by addressing potential concerns regarding the implementation of methods by government agencies in future initiatives and outreach.

Changes in wild pig (Sus scrofa) relative abundance, crop damage, and environmental impacts in response to control efforts.

As the population and range of wild pigs (Sus scrofa) continue to grow across North America, there has been an increase in environmental and economic damages caused by this invasive species, and control efforts to reduce damages have increased concomitantly. Despite the expanding impacts and costs associated with population control of wild pigs, the extent to which wild pig control reduces populations and diminishes environmental and agricultural damages are rarely quantified. The goal of this study is to quantify changes in wild pig relative abundance and subsequent changes in damages caused by invasive wild pigs in response to control. Using a combination of wild pig population surveys, agricultural damage assessments, and environmental rooting surveys across 19 mixed forest-agricultural properties in South Carolina, USA, we quantified changes in wild pig relative abundance and associated damages over a 3-year period following implementation of a professional control program. Following implementation of control efforts, both the number of wild pig detections and estimated abundance decreased markedly. Within 24 months relative abundance was reduced by an average of ~70%, which resulted in a corresponding decline in environmental rooting damage by ~99%. Our findings suggest that sustained wild pig control efforts can substantially reduce wild pig relative abundance, which in turn resulted in a reduction in environmental rooting damage by wild pigs. Ultimately this study will help fill critical knowledge gaps regarding the efficacy of wild pig control programs and the effort needed to reduce impacts to native ecosystems, livestock, and crops. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Assessment of Spilled Toxic Bait by Wild Pigs and Potential Risk to Non-target Species.

In 2018, a sodium nitrite-based toxic bait for invasive wild pigs (hereafter; wild pigs; Sus scrofa), was evaluated to determine its effectiveness in reducing local wild pig populations in Texas. Localized population reductions of >70% were achieved, but spillage of bait outside wild pig-specific feeders (hereafter: bait stations) caused by feeding wild pigs resulted in the deaths of non-target animals. To evaluate risks to non-target animals, we tested whether bait presentation influenced the total amount of bait spilled by wild pigs and estimated associated risk to non-target species. We found that bait spilled outside of bait stations could be reduced by >90% when compacted in trays, as opposed to being manually crumbled into pieces. We documented a mean spill rate of 0.913 g of bait per-wild pig. Conservative risk assessments for nine non-target species for which SN toxicity data exist indicate that there is relatively low risk of lethal exposure, apart from zebra finches (Taeniopygia guttata) and white mice. Our results indicate that there may be enough spilled bait per-feeding wild pig to kill 9.5 or 3.5 individuals of these species, respectively. Other species assessed range from 0.002 to 0.406 potential mortalities per-wild pig. We demonstrated that the amount of bait spilled by wild pigs during feeding and associated risk to non-target animals can be minimized by presenting the bait compacted in trays within bait stations. We recommend that baits be tightly compacted and secured into bait stations to minimize risks to non-target animals from spilled bait by wild pigs. This article is protected by copyright. All rights reserved.

Type and frequency of wild pig-domestic livestock contacts and operator concern for disease spread

Abstract Wild pigs (Sus scrofa) can levy substantial costs to domestic livestock operations and global supply chains due to disease introduction. Producers can take defensive action to avert these costs, but the factors influencing these decisions are not well understood. We examined survey data to characterize the type and frequency of contacts between wild pigs and domestic livestock and investigated the determinants of farm operator concern for disease introduction using an ordered logit model. We found that operators with livestock kept in buildings were more concerned about disease than those with livestock kept in fenced areas or that roam free. However, the latter are at greater risk due to more frequent reported contacts with wild pigs. Results indicate that concern is significantly associated with other characteristics of farm operations, such as operation size, perceived change in wild pig populations, and respondent demographics. Developing a better understanding of the factors influencing operator concern for disease spread can contribute to the improved design of prevention policy targeting small-scale livestock producers. This could help ensure the continued safety of livestock supply chains and reduce the risk of disease-related trade restrictions, along with continued support for disease surveillance and monitoring at the national scale, and prolonged control of domestic vectors such as invasive wild pigs, specifically in regions with the most small operations.