Assessing methods to live-capture wild boars (Sus scrofa) in urban and peri-urban environments

Between conflict and reciprocal habituation: Human-wild boar coexistence in urban areas

Urbanization is an ongoing global environmental change. Wildlife may respond using anthropized environments and resources, which is known as synurbization, creating human-wildlife interactions. Wild boar (Sus scrofa) populations have become common in urban areas, including the metropolitan area of Barcelona. Humans respond to wild boars in urban environments either habituating, with lower conflict perception and higher wild boar acceptance, or sensitizing, with reduced tolerance towards wild boars. Since citizen response influences conflict management, this study analysed the drivers of human responses, which should allow adopting socially-accepted measures to manage synurbic wild boar populations. Interviews to 1956 Barcelona citizens were performed, grouping the response variables to score citizen and urban characteristics, as well as citizen lay-knowledge, emotions, experiences, and perception of wild boar. Five citizen clusters were identified: cluster 1 (3.3 %), highly habituated and active wild boar feeder; cluster 2 (11.3 %), habituated to wild boars with positive feelings; cluster 3 (19.8 %), not habituated nor sensitized, willing to maintain urban wild boar populations; cluster 4 (29.1 %), sensitized and concerned, defending to reduce wild boar; and cluster 5 (40.1 %), highly sensitized and proposing to reduce or even eliminate wild boar. Positive attitudes associated wild boar to aesthetic value, closeness to nature and sympathy, and were more frequent in young citizens with urban background and high education, animal lovers habituated to wild boar through contact without negative experiences. Conversely, negative attitudes were concerned about city fouling, safety or health, accepted lethal management measures, and were more frequent in older citizens with rural background, lower education, low contact with wild boar or sensitized through negative experiences. We document for the first time the sensitization and reciprocal habituation of humans to wild boar in urban areas. The identification of the drivers of citizen attitudes towards urban wildlife should be useful to design socially-accepted management measures.

Refining animal welfare of wild boar (Sus scrofa) corral-style traps through behavioral and pathological investigations

Wild boar trapping has been used as a management tool to control wild boar populations. However, it is increasingly criticized due to animal welfare concerns. While cortisol levels have been used to assess trap-related stress in wild boar, data on trap-related injuries and behavioral data are scarce. We aimed to evaluate three different corral-style traps for wild boar according to available mammal trapping standards to investigate and refine animal welfare in wild boar trapping. We examined 138 wild boars captured and killed by head shot in 27 capture events. Traps were closed by remote control only if the complete group were trapped. The behavior of the animals in the trap and during culling was recorded on video. All wild boars were examined and a pathological and radiological examination of the heads for trap- and shot-related injuries followed. Trap-related injuries occurred in 33% of the animals with superficial mild skin defects to skull fractures. One out of three traps met all the set requirements. A wire-meshed trapping system failed all. After installing an incomplete barrier in the center of the trap to slow down trapped animals, the fracture rate in one trap type was significantly reduced by 29% (p < 0.05). Our data showed that the type of trap (p = 0.007) and the number of animals trapped at once (p = 0.002) had a significant influence on the number of escape attempts. Trapping larger groups reduced the escape attempts. We emphasize the importance of an accurate pathological examination to evaluate animal welfare in traps and call for adjusting the injury categories listed in the standards and make a proposal for wild boar live trapping.

The prohibition of recreational hunting of wild ungulates in Spanish National Parks: Challenges and opportunities

A new regulation has led to the prohibition of recreational hunting on estates located within Spanish National Parks (NPs). Before the ban, eleven NPs in Spain had already reported negative ecological consequences associated with high densities of wild ungulates. The new situation that has occurred after the ban signifies that policies with which to control populations of wild ungulates in NPs, most of which do not have a sufficient natural capacity to regulate populations, depend exclusively on the parks' authorities. The banning of recreational hunting implies a series of social, ecological, economic and logistic challenges. The control of wild ungulate populations in NPs requires: i) the legal basis for culling; ii) social acceptance as regards removing animals and the extractive procedures employed in NPs; iii) the long-term monitoring of wild ungulates and the damages that they cause, and iv) sufficient financial and human resources. A more integrated management and policy plan is, therefore, required, which should be supported by two pillars: i) the sustainability of natural resources and the conservation of functional environments, and ii) providing society with explanations regarding the need to manage wild ungulates. In order to bridge the potential gap between these key pillars, it is important to involve stakeholders in the decision-making processes concerning wild ungulate management. The forthcoming changes in Spanish NPs provide a promising opportunity to make a substantial improvement to wild ungulate management in these protected areas. This management approach could, moreover, serve as an example and be transferred to other protected spaces.

Biomonitoring of parabens in wild boars through hair samples analysis

Parabens are compounds widely utilized in the industry as preservative additives to personal care products, cosmetics and food. They pollute the environment and penetrate to the living organisms through the digestive tract, respiratory system and skin. Till now the knowledge about exposure of terrestrial wild mammals to parabens is extremely scarce. Therefore, this study for the first time assessed the concentration levels of five parabens commonly used in industry (methylparaben-MeP, ethylparaben-EtP propylparaben-PrP, benzylparaben -BeP and butylparaben-BuP). Substances have been analyzed in hair samples collected from wild boars using liquid chromatography-mass spectrometry (LC-MS) method. The hair is a matrix, which allows to study long-term exposure of organisms to parabens. During this study MeP was noted in 96.3% of samples with mean 88.3±72.9 pg/mg, PrP in 87.0% of samples with mean 8.5±3.3 pg/mg, BeP in 44.4% of samples with mean 17.2±12.3 pg/mg and EtP in 11.1% of samples with mean 17.2±4.8 pg/mg. In turn BuP was noted only in 3.7% of samples with concentration levels below limit of quantification (2.6 pg/mg). Statistically significant intragender differences in parabens levels have not been noted. Only BeP concentration levels depended on industrialization and density of human population of area, where the animals lived. This study indicates that wild boars are exposed to parabens, especially to MeP and PrP, and analysis of the hair seems to be a useful tool of biomonitoring of parabens in wild mammals.

Exposure assessment to bisphenol A (BPA) and its analogues bisphenol S (BPS) and bisphenol F (BPF) in wild boars by hair analysis

Bisphenols are widely used in various branches of industry for the production of plastics. They penetrate to the natural environment and thus living organisms. As endocrine disruptors, bisphenols have adverse effects on various internal organs and systems. Contrary to humans, the knowledge of the exposure of wild terrestrial mammals to bisphenols is extremely limited. Therefore, this study for the first time assessed the exposure level of wild boars to three bisphenols commonly used in industry (i.e. bisphenol A - BPA, bisphenol S - BPS and bisphenol F - BPF) using hair sample analysis in liquid chromatography-mass spectrometry (LC-MS). The presence of BPA and/or BPS has been noted in the samples collected from >80 % of animals included in the study (n = 54), while the presence of BPF was not found in any sample. At least one of the bisphenols was present in every sample tested. Mean concentrations of BPA and BPS in the hair of wild boars were 151.40 ± 135.10 pg/mg dry weight (dw.) and 29.40 ± 36.97 pg./mg dw, respectively. Concentrations of BPA and BPS in females were statistically higher than in males (p < 0.05). Moreover, statistically significantly higher concentration levels of BPA (and not BPS) in the areas with higher degree of industrialization and higher human population density were also found. This is the first study concerning the use of hair samples to assess the exposure of wild terrestrial mammals to bisphenols. The obtained results show that an analysis of the hair may be a useful tool of biomonitoring bisphenols in wild animals. The presence of BPA and BPS in wild boar hair in relatively high concentration also suggests that these substances may have an influence on the health status not only in humans and aquatic animals, but also in wild terrestrial mammals. However, many aspects connected with this issue are not clear and require further study.

Assessing the epidemiological risk at the human-wild boar interface through a one health approach using an agent-based model in Barcelona, Spain

Wild boar (WB, Sus scrofa) populations are increasing in urban areas, posing an epidemiological risk for zoonotic pathogens such as hepatitis E virus (HEV) and antimicrobial-resistant Campylobacter (AMR-CAMP), as well as non-zoonotic pathogens such as African swine fever virus (ASFV). An epidemiological extension of a validated Agent-Based Model (ABM) was developed to assess the one-year epidemiological scenarios of HEV, AMR-CAMP, and ASFV in the synurbic WB-human interface in Barcelona, Spain. The predicted citizen exposure was similar for HEV and AMR-CAMP, at 0.79% and 0.80% of the human population in Barcelona, respectively, despite AMR-CAMP being more prevalent in the WB population than HEV. This suggests a major role of faeces in pathogen transmission to humans in urban areas, resulting in a non-negligible public health risk. The ASFV model predicted that the entire WB population would be exposed to the virus through carcasses (87.6%) or direct contact (12.6%) in 51-71 days after the first case, with an outbreak lasting 71-124 days and reducing the initial WB population by 95%. The ABM predictions are useful for animal and public health risk assessments and to support risk-based decision-making. The study underscores the need for interdisciplinary cooperation among animal, public, and environmental health managers, and the implementation of the One Health approach to address the epidemiological and public health risks posed by the synurbization of WB in urban areas. The spatially explicit epidemiological predictions of the ABM can be adapted to other diseases and scenarios at the wildlife-livestock-human interface.

Wild boar captured in a large corral-style trap or hunted: preliminary comparison of meat quality traits

The management and numerical control of wild boars mainly depend on hunting practices, even if other alternative strategies such as the use of traps and cages can be adopted. There is little information available on the quality of captured wild boar meat. The aim of this study was to evaluate the meat quality of wild boars captured with a large corral-style trap compared to still hunting and collective hunting methods. Longissimus dorsi samples were collected from 60 wild boars, 20 of which were obtained by trapping, 20 by still hunting, and 20 by collective hunting. The animals considered were 32 males and 28 females, weighing between 42 and 68 kg. Muscle pH has been recorded at 1, 24, and 48 hours post-mortem. Furthermore, after 24 hours, color, drip loss, cooking loss, and Warner-Bratzler shear force were also evaluated. Trapping with large enclosures such as corral-style traps, if properly managed, does not seem to adversely affect the quality traits of wild boar meat, which were found to be like those obtained by the still hunting method.

Stress Assessment of Wild Boar (Sus scrofa) in Corral-Style Traps Using Serum Cortisol Levels

Simple Summary

Corral-style traps for wild boar are used to reduce the number of wild boars. However, many people criticise these traps because of animal welfare issues such as stress and panic. While previous studies focused on behaviour and injuries, this study focused on the so-called stress hormone cortisol. Cortisol levels from trapped animals were compared with levels from animals shot during other hunting methods. Inside traps animals were killed by headshot within 2 h and 17 min after trapping and blood samples were directly taken. Cortisol levels were higher in wild boar killed in traps than in driven hunts and single hunts. Wild boar caught in groups of five or more showed lower cortisol levels than single animals or animals in smaller groups. Therefore, the time animals spend inside the trap and the time of culling all animals should be as short as possible. To reduce stress, it is better to capture larger groups of animals instead of single animals. For the evaluation of harm and stress for wild boar in live traps, cortisol levels alone are not sufficient. Additional information about the behaviour and injuries must be integrated.

Abstract

Capture of wild boar in corral-style traps with subsequent culling is increasingly used for population management. The method is debated due to animal welfare concerns making welfare studies in traps necessary. While previous studies focused on behaviour and injuries, this study dealt with the physiological aspect. Cortisol levels in wild boar caught in corral-style traps (50–90 qm², n = 138) were compared with those killed during single (n = 37) and driven hunts (n = 90). Collected sera were purified by solid phase extraction (SPE) and analysed via radioimmunoassay. Cortisol levels in blood samples were stable under cooled (4–7 °C) conditions for a storage time of up to 87 h before centrifugation. Cortisol levels were significantly higher in wild boar killed in corral-style traps than during driven hunts and single hunts. Wild boar caught in groups of five or more showed lower cortisol levels than single animals or in smaller groups. Therefore, time span inside the trap and of culling should be reduced to a minimum, and capturing groups of animals should be preferred to reduce stress. For animal welfare assessment of wild boar live-trapping, additional data from behavioural analyses and pathological examinations must be integrated.

Assessing mammal trapping standards in wild boar drop-net capture

Applying contemporary trapping standards when managing wildlife should no longer be an option, but a duty. Increasing wild boar populations originate a growing number of conflicts and hunting is the only cost-effective management option in most cases. However, new scenarios where hunting is unfeasible emerge and trapping necessities cope with lacking regulatory frameworks and technical guidelines. In this research, we evaluated drop nets, a capture method not considered by the international trapping standards, to capture Eurasian wild boar (Sus scrofa), a wildlife species not included in the list of mammal species under the scope of the Agreement on International Humane Trapping Standards (AIHTS). Less than 20% of the captured wild boars presented moderate or severe injuries attributable to the capture method, hence fulfilling the acceptance thresholds of the outdated AIHTS. Based on the new standards thresholds of acceptance, the humaneness of drop-nets in our study ranged 66-78%, under the 85% required. The capture success and selectivity were 100%, as ensured by operator-driven triggering, which should be considered the main strengths of this method, together with the minimization of animal suffering owing the short duration of the stressful situation. Additionally, in spite of the socially adverse environment, with people contrary to wild boar removal, no disturbances against the capture system or operations occurred. This is the first assessment of a drop-net capture method according to internationally accepted mammal trapping standards, with unconclusive results. However, there is a need for adapted procedures and thresholds of acceptance aimed at not-mechanical traps in general, and specifically at drop-nets. Compared to other live-capture methods, drop-nets minimize the duration of the stressful situation -at the expense of a strong adrenergic acute response-, maximize the probabilities of capturing entire sounders of prosocial species, which may be also considered as more humane, and has the ability to coordinate higher values of capture success, absolute selectivity and adaptability to difficult environments.

Genetic population structure defines wild boar as an urban exploiter species in Barcelona, Spain

Urban wildlife ecology is gaining relevance as metropolitan areas grow throughout the world, reducing natural habitats and creating new ecological niches. However, knowledge is still scarce about the colonisation processes of such urban niches, the establishment of new communities, populations and/or species, and the related changes in behaviour and life histories of urban wildlife. Wild boar (Sus scrofa) has successfully colonised urban niches throughout Europe. The aim of this study is to unveil the processes driving the establishment and maintenance of an urban wild boar population by analysing its genetic structure. A set of 19 microsatellite loci was used to test whether urban wild boars in Barcelona, Spain, are an isolated population or if gene flow prevents genetic differentiation between rural and urban wild boars. This knowledge will contribute to the understanding of the effects of synurbisation and the associated management measures on the genetic change of large mammals in urban ecosystems. Despite the unidirectional gene flow from rural to urban areas, the urban wild boars in Barcelona form an island population genotypically differentiated from the surrounding rural ones. The comparison with previous genetic studies of urban wild boar populations suggests that forest patches act as suitable islands for wild boar genetic differentiation. Previous results and the genetic structure of the urban wild boar population in Barcelona classify wild boar as an urban exploiter species. These wild boar peri-urban island populations are responsible for conflict with humans and thus should be managed by reducing the attractiveness of urban areas. The management of peri-urban wild boar populations should aim at reducing migration into urban areas and preventing phenotypic changes (either genetic or plastic) causing habituation of wild boars to humans and urban environments.

Zoonotic Campylobacter spp. and Salmonella spp. carried by wild boars in a metropolitan area: occurrence, antimicrobial susceptibility and public health relevance

Campylobacter spp. and Salmonella spp. are the most reported zoonotic agents in Europe. They can be transmitted from wildlife to humans, and wild boars (Sus scrofa) can harbour them. In the Metropolitan Area of Barcelona (MAB, NE Spain) wild boars are found in urbanized areas. To assess the potential public health risk of this increasing wild boar population, we collected stool samples from 130 wild boars from the MAB (June 2015 - February 2016), to determine the Campylobacter and Salmonella occurrence and the antimicrobial susceptibility of the isolates. We also investigated the genetic diversity and virulence potential of Campylobacter. Campylobacter prevalence in wild boars was 61%. Forty six percent of wild boars carried Campylobacter lanienae, 16% carried Campylobacter coli, and 1% carried Campylobacter hyointestinalis; 4% carried both C. lanienae and C. coli, and 1% carried both C. lanienae and C. hyointestinalis. This is the first report of C. hyointestinalis in wildlife in Spain. Using pulse-field gel electrophoresis and multilocus sequence typing, we observed a high genetic diversity of Campylobacter and identified new sequence types. Thirty-three percent of C. coli and 14% of C. lanienae isolates showed a high virulence potential. All of the Campylobacter isolates analysed were resistant to at least one antimicrobial agent. Multidrug resistance was only detected in C. coli (67%). Salmonella enterica subsp. enterica was detected in four wild boars (3%) and included a S. Enteritidis serovar (1/4 wild boars) and a multidrug-resistant (ASSuT) monophasic S. Typhimurium serovar (1/4 wild boars) which is associated with human infections and pig meat in Europe. The characteristics of some of the Campylobacter and Salmonella isolates recovered suggest an anthropogenic origin. Wild boars are a reservoir of Campylobacter and have the potential to spread antimicrobial resistant Campylobacter and Salmonella in urbanized areas in the MAB.

Measurement of catestatin and vasostatin in wild boar Sus scrofa captured in a corral trap

Objective

Our aim was to analyse the chromogranin A-derived peptides vasostatin and catestatin in serum from wild boar (Sus scrofa) captured in a corral trap. Acute capture-related stress quickly leads to a release of adrenalin and noradrenalin, but these hormones have a short half-life in blood and are difficult to measure. Chromogranin A (CgA), a glycoprotein which is co-released with noradrenalin and adrenalin, is relatively stable in circulation and the CgA-derived peptides catestatin and vasostatin have been measured in domestic species, but not yet in wildlife.

Results

Vasostatin and catestatin could be measured and the median (range) serum concentrations were 0.91 (0.54–2.86) and 0.65 (0.35–2.62) nmol/L, respectively. We conclude that the CgA-derived peptides vasostatin and catestatin can be measured in wild boar serum and may thus be useful as biomarkers of psychophysical stress.

Observation of rescue behaviour in wild boar (Sus scrofa)

Here, we provide unique photo documentation and observational evidence of rescue behaviour described for the first time in wild boar. Rescue behaviour represents an extreme form of prosocial behaviour that has so far only been demonstrated in a few species. It refers to a situation when one individual acts to help another individual that finds itself in a dangerous or stressful situation and it is considered by some authors as a complex form of empathy. We documented a case in which an adult female wild boar manipulated wooden logs securing the door mechanism of a cage trap and released two entrapped young wild boars. The whole rescue was fast and particular behaviours were complex and precisely targeted, suggesting profound prosocial tendencies and exceptional problem-solving capacities in wild boar. The rescue behaviour might have been motivated by empathy because the rescuer female exhibited piloerection, a sign of distress, indicating an empathetic emotional state matching or understanding the victims. We discuss this rescue behaviour in the light of possible underlying motivators, including empathy, learning and social facilitation.

Research priorities to fill knowledge gaps in wild boar management measures that could improve the control of African swine fever in wild boar populations

The European Commission asked EFSA to provide study designs for the investigation of four research domains (RDs) according to major gaps in knowledge identified by EFSA in a report published in 2019: (RD 1) African swine fever (ASF) epidemiology in wild boar; (RD 2) ASF transmission by vectors; (RD 3) African swine fever virus (ASFV) survival in the environment, and (RD 4) the patterns of seasonality of ASF in wild boar and domestic pigs in the EU. In this Scientific Opinion, the second RD on ASF epidemiology in wild boar is addressed. Twenty-nine research objectives were proposed by the working group and broader ASF expert networks and 23 of these research objectives met a prespecified inclusion criterion. Fourteen of these 23 research objectives met the predefined threshold for selection and so were prioritised based on the following set of criteria: (1) the impact on ASF management; (2) the feasibility or practicality to carry out the study; (3) the potential implementation of study results in practice; (4) a possible short time-frame study (< 1 year); (5) the novelty of the study; and (6) if it was a priority for risk managers. Finally, after further elimination of three of the proposed research objectives due to overlapping scope of studies published during the development of this opinion, 11 research priorities were elaborated into short research proposals, considering the potential impact on ASF management and the period of one year for the research activities.

Wild boar in the city: Phenotypic responses to urbanisation

Urbanisation is a global human-induced environmental change and one of the most important threats to biodiversity. To survive in human-modified environments, wildlife must adjust to the challenging selection pressures of urban areas through behaviour, morphology, physiology and/or genetic changes. Here we explore the effect of urbanisation in a large, highly adaptable and generalist urban adapter species, the wild boar (Sus scrofa, Linnaeus 1758). From 2005 to 2018, we gathered wild boar data and samples from three areas in NE Spain: one urban (Barcelona municipality, n = 445), and two non-urban (Serra de Collserola Natural Park, n = 183, and Sant Llorenç del Munt i Serra de l'Obac Natural Park, n = 54). We investigated whether urbanisation influenced wild boar body size, body mass, body condition, and the concentration of serum metabolites, considering also the effect of age, sex and use of anthropogenic food resources. Wild boars from the urban area had larger body size, higher body mass, better body condition, and a higher triglyceride and lower creatinine serum concentrations than non-urban wild boars. In addition, urban wild boars consumed food from anthropogenic origin more frequently, which suggests that differences in their diet probably induced the biometric and the metabolic changes observed. These responses are probably adaptive and suggest that wild boars are thriving in the urban environment. Our results show that urbanisation can change the morphological and physiological traits of a large mammal urban adapter, which may have consequences in the ecology and response to urban selection pressures by the species. The phenotypic plasticity shown by wild boars provides both further and new evidence on the mechanisms that allow urban adapter species of greater size to respond to urbanisation, which is expected to continue growing globally over the coming decades.

Detection of Beta-Lactam-Resistant Escherichia coli and Toxigenic Clostridioides difficile Strains in Wild Boars Foraging in an Anthropization Gradient

Disease transmission among wild boars, domestic animals and humans is a public health concern, especially in areas with high wild boar densities. In this study, fecal samples of wild boars (n = 200) from different locations of the Metropolitan Area of Barcelona were analyzed by PCR to explore the frequency of β-lactamases and extended cephalosporin and carbapenem resistance genes (ESBLs) in Escherichia coli strains and the presence of toxigenic Clostridioides difficile. The prevalence of genes conferring resistance to β-lactam antimicrobials was 8.0% (16/200): bla_CMY-2 (3.0%), bla_TEM-1b (2.5%), bla_CTX-M-14 (1.0%), bla_SHV-28 (1.0%), bla_CTX-M-15 (0.5%) and bla_CMY-1 (0.5%). Clostridioides difficile TcdA+ was detected in two wild boars (1.0%), which is the first report of this pathogen in wild boars in Spain. Moreover, the wild boars foraging in urban and peri-urban locations were more exposed to AMRB sources than the wild boars dwelling in natural environments. In conclusion, the detection of E. coli carrying ESBL/AmpC genes and toxigenic C. difficile in wild boars foraging in urban areas reinforces the value of this game species as a sentinel of environmental AMRB sources. In addition, these wild boars can be a public and environmental health concern by disseminating AMRB and other zoonotic agents. Although this study provides the first hints of the potential anthropogenic sources of AMR, further efforts should be conducted to identify and control them.

Effectiveness and Efficiency of Corral Traps, Drop Nets and Suspended Traps for Capturing Wild Pigs (Sus scrofa)

Simple Summary

New or revised techniques are being developed to improve management of expanding populations of invasive wild pigs. In southern Oklahoma, we set out to evaluate the success of various trap types: a conventional corral trap design, drop nets developed for capturing other wildlife, and recently developed suspended traps. Suspended traps removed 88.1% of the estimated population of wild pigs, whereas drop nets removed 85.7% and corral traps removed 48.5%. Suspended traps removed one pig for every 0.64 h invested in control, whereas drop nets had a 1.9 h investment per pig and corral traps had a 2.3 h investment per pig. Drop nets and suspended traps removed more of the wild pig population, mainly through whole sounder removal. The suspended trap required the least amount of time per pig removed because of real-time notifications and remote actuation from a cell phone. Drop nets and suspended traps offer greater control and time savings with the use of remote technology, making intensive, large-scale removal of pigs possible. Now, with commercially available technology, corral traps also can be configured to be user operated with real-time monitoring and trapping.

Abstract

Strategic control and eradication programs for wild pigs (Sus scrofa) are being developed to help curtail the expanding populations of this invasive, alien species. Drop nets and corral traps have a long history of capturing a multitude of wildlife species, so we evaluated the effectiveness and efficiency of these traps for controlling wild pigs in southern Oklahoma. We also developed and evaluated a suspended metal trap that provided real-time monitoring and deployment to capture animals. Effectiveness of each trap type was estimated as the proportion of pigs removed from the total population, whereas efficiency was calculated based on catch per unit effort (CPUE) (i.e., the number of person hours per pig removal). During 3 years of study (2010–2012), we removed 601 pigs, 296 using drop nets, 60 using corral traps, and 245 using suspended traps. Suspended traps removed 88.1% of the estimated population, whereas drop nets removed 85.7% and corral traps removed 48.5%. CPUE was 0.64 person hours/pig using suspended traps followed by 1.9 person hours/pig for drop nets and 2.3 person hours/pig for corral traps. Drop nets and suspended traps were more effective at removing a large proportion of the population (>85%), mainly through whole sounder removal, but the suspended trap with real-time notifications was the most efficient trap type, requiring fewer person hours to operate.