Trap style influences wild pig behavior and trapping success

Despite the efforts of many natural resource professionals, wild pig (Sus scrofa) populations are expanding in many areas of the world. Although many creative techniques for controlling pig populations are being explored, trapping has been and still is the most commonly used method of population control for many public and private land managers. We conducted an observational study to examine the efficiency of 2 frequently used trap styles: a small, portable box-style trap and a larger, semi-permanent, corral-style trap. We used game cameras to examine patterns of trap entry by wild pigs around each style of trap, and we conducted a trapping session to compare trapping success between trap styles. Adult female and juvenile wild pigs entered both styles of trap more readily than did adult males, and adult males seemed particularly averse to entering box traps. Less than 10% of adult male visits to box traps resulted in entries, easily the least percentage of any class at any style of trap. Adult females entered corral traps approximately 2.2 times more often per visit than box traps and re-entered corral traps >2 times more frequently. Juveniles entered and re-entered both box and corral traps at similar rates. Overall (all-class) entry-per-visit rates at corral traps (0.71) were nearly double that of box traps (0.37). Subsequent trapping data supported these preliminary entry data; the capture rate for corral traps was >4 times that of box traps. Our data suggest that corral traps are temporally and economically superior to box traps with respect to efficiency; that is, corral traps effectively trap more pigs per trap night at a lower cost per pig than do box traps. © 2011 The Wildlife Society.     

Efficiency of time-lapse intervals and simple baits for camera surveys of wild pigs

Growing concerns surrounding established and expanding populations of wild pigs (Sus scrofa) have created the need for rapid and accurate surveys of these populations. We conducted surveys of a portion of the wild pig population on Fort Benning, Georgia, to determine if a longer time-lapse interval than had been previously used in surveys of wild pigs would generate similar detection results. We concurrently examined whether use of soured corn at camera sites affected the time necessary for pigs to locate a new camera site or the time pigs remained at a site. Our results suggest that a 9-min time-lapse interval generated dependable detection results for pigs and that soured corn neither attracted pigs to a site any quicker than plain, dry, whole-kernel corn, nor held them at a site longer. Maximization of time-lapse interval should decrease data and processing loads, and use of a simple, available bait should decrease cost and effort associated with more complicated baits; combination of these concepts should increase efficiency of wild pig surveys. © 2011 The Wildlife Society.     

Mitochondrial lineages reveal intense gene flow between Iberian wild boars and South Iberian pig breeds

The phylogeography of wild boars (WB) and domestic pigs (Sus scrofa) has contributed important insights into where and when domestication occurred. The geographic distribution of two core haplotypes (E1a and E1c) of the main European phylogenetic clade suggests that Central Europe was an early domestication centre, although the complexity of the pattern does not exclude the possibility that multiple domestication events occurred in different regions. To investigate the relationships among WB and domestic pig breeds in Iberia, a fragment of the mitochondrial DNA control region from a large sample (n = 409) of WB and local pig breeds was co‐analysed with published sequences from other European populations. The Iberian sample revealed a high frequency of a sub‐cluster (E1c) of the European haplogroup E1 in 77% of total Iberian samples, 96% of WB, 90% of Alentejano (Portugal) and 87% of Iberian breed pigs (Spain; Black Hairy, Black Hairless and Red varieties). Low genetic distance (F’_ST = 0.105) was observed between Alentejano (Portugal) and Iberian breed pigs (Spain). Alentejano and Iberian breed pigs showed low genetic distances to both Iberian and Central European WB (average F’_ST = 0.345 and 0.215, respectively). This pattern suggests that early pig husbandry in the Iberian Peninsula did not solely rely on imported Central European stock, but also included the recruitment of local WB.     

伏牛山北坡野猪(Sus scrofa)泥浴场的生境特征

2005年6月至8月,在伏牛山北坡对野猪的泥浴场特征进行了研究.野外设置了42个20×20m2样方和14个生态因子,以此为基准运用聚类分析和主成分分析的方法,对野猪泥浴场进行了分析,结果表明,野猪泥浴场的生境特征为:(1)安全舒适因子:无倒木、无树桩、隐蔽距离30m以下、黄泥土质、郁闭度80%以上;(2)植被地形因子:乔木距离适中、灌木距离小于1m、坡度小于30°;(3)植被类型因子:高度倾向阔叶林;(4)干扰因子:人为干扰距离大于500 m;(5)海拔因子:海拔高度大于1000 m.在水源距离和坡位两项上没有明显的偏向.     

Genetic relationship and distribution of the Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (Sus scrofa riukiuanus) analysed by mitochondrial DNA

Mitochondrial genetic variations were used to investigate the relationships between two Japanese wild boars, Japanese wild boar (Sus scrofa leucomystax) and Ryukyu wild boar (S.s. riukiuanus). Nucleotide sequences of the control (27 haplotypes) and cytochrome b (cyt-b) regions (19 haplotypes) were determined from 59 Japanese wild boars, 13 Ryukyu wild boars and 22 other boars and pigs. From phylogenetic analyses, the mtDNA of Ryukyu wild boar has a distinct lineage from that of Japanese wild boar, which was classified into the Asian pig lineage. This result suggests that the Ryukyu wild boar has a separate origin from the Japanese wild boar.     

Molecular characterization of the complete mitochondrial genome sequence of Indian wild pig (Sus scrofa cristatus)

The Indian wild pig is a sub-species (Sus scrofa cristatus) which is different from the other pig breeds and is protected under Schedule-III of the Indian Wildlife (Protection) Act, 1972. In this study, complete mitogenome of two Indian wild pigs was sequenced and characterized by shotgun sequencing and de novo assembly, which revealed sequence size of 16,738 and 16,251?bp, respectively, (Accession no. MG725630 and MG725631). The mitogenome sequence in this study displayed 98% homology with previously reported mitogenome of pigs from different parts of the world. Mitogenome analysis by MITOS Web server revealed similarity of gene organization with the other vertebrates (13 protein-coding, 22 tRNAs, 2 rRNAs genes, and a control region). The mitogenomic sequences of Indian wild pig maintained a separate clade in the phylogenetic tree constructed by using 62 whole mitogenome sequences across the world. The phylogeny derived from mitogenomic sequences revealed distinct separate European–American and Asiatic pig clades. It was concluded that whole mitogenome sequencing using NGS without designing mitogenome-specific primer for amplification, is possible thereby reducing the cost and labor. This study is the first report of complete sequence of mitogenome of Indian wild pig.     

Evaluating potential sources of invasive wild pigs in Ontario

Invasive wild pigs (Sus scrofa) are considered one of the most damaging species globally, and once they become established in an area, they are notoriously difficult to eliminate. As such, identifying the potential pathways of invasion, especially in places with emerging populations, is critical for preventing new or continued invasion. Wild pigs have been reported in Ontario, Canada, in recent years. We tested four nonexclusive hypotheses about the source of wild pigs in Ontario: (a) escapees from captive sources within Ontario; (b) invasion from neighboring jurisdictions; (c) existing wild populations within Ontario; and (d) translocation and illegal release. We found that sightings of Eurasian wild boar were closer to premises with wild boar than were random locations; wild boar sightings were an average of 16.3 km (SD = 25.4 km, min = 0.2 km, n = 20) from premises with wild boar. We also found that sightings of domestic pigs were closer to domestic pig farms than expected. Sightings of wild pigs in groups of more than four animals were rare. Our results suggest that wild pigs observed in Ontario are recent escapes from captivity, recognizing that there may be established groups of wild pigs that we have not yet detected. While not common, we also received reports indicating that in the past, wild pigs have been translocated and illegally released. Other North American jurisdictions that have been successful at eliminating wild pigs have removed existing populations and changed regulations to limit future invasion, such as prohibiting possession and transport of wild boar and prohibiting hunting of wild pigs.     

Dispersal of freshwater invertebrates by large terrestrial mammals: a case study with wild boar (Sus scrofa) in Mediterranean wetlands

1. Many invertebrates inhabiting insular aquatic habitats rely on external agents or vectors to disperse. Besides water connections and wind, waterfowl and amphibians are known to mediate passive dispersal of freshwater invertebrates. However, the possibility of dispersal by terrestrial mammals has been largely overlooked. 2. We investigated the potential of both external and internal zoochorous dispersal of aquatic invertebrates by the wild boar (Sus scrofa) in Mediterranean wetlands in the Camargue (France). As wild boar frequently visit wetlands for feeding and wallowing purposes, we hypothesized that they may be important passive dispersal vectors of aquatic invertebrates at a local scale. Dried mud was collected from selected ‘rubbing trees’ used by boars to dispose of parasites. Additionally, faecal pellets were collected from different locations in the wetland area. 3. Seventeen freshwater invertebrate taxa including rotifers, cladocerans, copepods and ostracods hatched from sediment obtained from ‘rubbing trees’, while invertebrates hatching from dried faeces (10 taxa) were mainly rotifers. Dispersing invertebrates were collected up to 318 m from a nearest potential dispersal source. Both abundance and richness of invertebrates significantly decreased with dispersal distance. 4. Our results demonstrate that large mammals such as wild boar can act as dispersal vectors of aquatic invertebrates at a local scale in the wetland area of the Camargue and suggest that external transport may be quantitatively more important than internal transport. As wallowing (mud bathing) is common in many terrestrial mammals, this mode of dispersal may be quite widespread.     

Multiple paternity in a natural population of a wild tobacco fly, Bactrocera cacuminata (Diptera: Tephritidae), assessed by microsatellite DNA markers

Mating frequency has important implications for patterns of sexual selection and sexual conflict and hence for issues such as speciation and the maintenance of genetic diversity. Knowledge of natural mating patterns can also lead to more effective control of pest tephritid species, in which suppression programmes, such as the sterile insect technique (SIT) are employed. Multiple mating by females may compromise the success of SIT. We investigated the level of polyandry and sperm utilization in a Brisbane field population of the tropical fruit fly, Bactrocera cacuminata (Hering), using seven polymorphic microsatellite loci. The offspring of 22 wild-caught gravid females were genotyped to determine the number of males siring each brood and paternity skew, using the programs gerud and scare. Our data showed that 22.7% of females produced offspring sired by at least two males. The mean number of mates per female was 1.72. Paternal contributions of double-sired broods were skewed with the most successful male having sired between 76.9% and 87.5% of the offspring. These results have implications for SIT, because the level of remating we have identified would indicate that wild females could mate with one or more resident fertile males.     

基于微卫星标记的中国大陆地区野猪种群结构分析与亚种分化

对中国大陆地区分布的野猪亚种分类尚存在争议.本研究通过对野猪11个微卫星位点的变异分析,探讨了中国大陆地区野猪的遗传结构,以期对野猪亚种分类问题有所启迪.对野猪华北、华南和东北种群的分析表明,各种群基因库中都维持了较高的遗传变异水平.基于遗传距离构建的系统树分析发现,研究中所涉及的所有亚种在系统树中混杂,没有任何亚种在其中构成显著的支系.基于微卫星变异的FCA分析不能区分华南、华北、东北三个种群.基于Fst检验的遗传差异分析发现,长江两侧的华南、华北种群之间的遗传差异较小(Fst=0.014),表明长江两侧的野猪可能存在着较高水平的基因流,长江并非是一个有效的空间隔离;东北地区野猪和华北、华南地区野猪之间的遗传差异相对较大(Fst=0.040、0.042),东北野猪可以作为独立的亚种S.s.ussuricus.     

Main roads and land cover shaped the genetic structure of a Mediterranean island wild boar population

Patterns of genetic differentiation within and among animal populations might vary due to the simple effect of distance or landscape features hindering gene flow. An assessment of how landscape connectivity affects gene flow can help guide management, especially in fragmented landscapes. Our objective was to analyze population genetic structure and landscape genetics of the native wild boar (Sus scrofa meridionalis) population inhabiting the island of Sardinia (Italy), and test for the existence of Isolation‐by‐Distance (IBD), Isolation‐by‐Barrier (IBB), and Isolation‐by‐Resistance (IBR). A total of 393 Sardinian wild boar samples were analyzed using a set of 16 microsatellite loci. Signals of genetic introgression from introduced non‐native wild boars or from domestic pigs were revealed by a Bayesian cluster analysis including 250 reference individuals belonging to European wild populations and domestic breeds. After removal of introgressed individuals, genetic structure in the population was investigated by different statistical approaches, supporting a partition into five discrete subpopulations, corresponding to five geographic areas on the island: north‐west (NW), central west (CW), south‐west (SW), north‐central east (NCE), and south‐east (SE). To test the IBD, IBB, and IBR hypotheses, we optimized resistance surfaces using genetic algorithms and linear mixed‐effects models with a maximum likelihood population effects parameterization. Landscape genetics analyses revealed that genetic discontinuities between subpopulations can be explained by landscape elements, suggesting that main roads, urban settings, and intensively cultivated areas are hampering gene flow (and thus individual movements) within the Sardinian wild boar population. Our results reveal how human‐transformed landscapes can affect genetic connectivity even in a large‐sized and highly mobile mammal such as the wild boar, and provide crucial information to manage the spread of pathogens, including the African Swine Fever virus, endemic in Sardinia.     

An empirical approach for reliable microsatellite genotyping of wolf DNA from multiple noninvasive sources

Wildlife management and conservation take advantage of the possibility to study free-living populations by collecting and analysing noninvasive samples. Nevertheless, the commonly adopted approaches, aimed at preventing results being affected by genotyping errors, considerably limit the applicability of noninvasive genotyping. An empirical approach is presented for achieving a reliable data set of wolf (Canis lupus) genotypes from multiple sources of DNA collected in a monitored population. This method relies on the relationship between sample quality and amplification outcome, which is ultimately related to the occurrence of typing errors (allelic dropout, false alleles). After DNA extraction, templates are amplified once at each locus and a conservative rating system (Q-score) is adopted to define the quality of single-locus amplifications. A significant relationship was found between quality scores and error rate (ER) (r ²=0.982). Thus it was possible to predict the chance a genotype has of being affected by errors on the basis of its Q-score. Genotypes not reaching a satisfactory confidence level can either be replicated to become reliable or excluded from the data set. Accordingly, in the present case study, 48–73% of all single-locus and 51–53% of all multilocus (ML) genotypes reached a sufficient (99 and 95%, respectively) reliability level after a single amplification per locus. Despite the possible decrease in overall yield, this method could provide a good compromise between accuracy in genotyping and effectiveness in screening large data sets for long-term or large-scale population surveys. However, to achieve complete and reliable data sets, replicated amplifications are necessary for those samples and loci providing poor results.An erratum to this article can be found at     

PGD variants in several wild pig populations of East Asia

PGD (6-phosphogluconate dehydrogenase) gene frequencies were reported in wild pigs, Sus scrofa, of three subspecies, i.e. Japanese wild pig, S.s. leucomystax, Ryukyu wild pig, S.s. riukiuanus, and Formosan wild pig, S.s. taivanus. Five phenotypes (A, AB, B, AC' and C') were observed. The C' variant was found only in the S.s. leucomystax, and may be identical to PGD-C reported by Archibald & McTeir (1988). PGD-A was a common variant in all the species in the genus Sus including wild pig, Sus scrofa, Javan pig, Sus verrucosus, and Bearded pig, Sus barbatus, and predominated in the whole populations examined except some of those of the S.s. riukiuanus. This suggested that the PGDA appeared before the other two alleles (B and C') during the evolution of the genus Sus.     

Reproduction in a population of wild pigs (Sus scrofa) subjected to lethal control

The continued range expansion of wild pigs (Sus scrofa) in North America is an increasing cause for concern because of the numerous negative impacts that wild pigs have on ecosystem structure and function. Once populations are established, wild pigs have proven to be extremely difficult to control, and close to impossible to eradicate. If effective control and removal techniques are to be developed, we must determine if wild pig populations respond to reductions in density by increasing reproductive output. This study was designed to examine if reproductive parameters of female wild pigs display a density-dependent response following a concentrated removal effort. We compared reproductive parameters and condition of adult sows that were collected between a control area and a treatment area where lethal removal occurred. From August 2004 to May 2006, we focused a concentrated removal effort within the treatment area. Although the population density was more than 65% greater in the control area than the treatment area during the study, we did not detect differences between areas for condition, litter size, ovarian mass, corpus luteum mass, or corpora lutea number. Several years of heavy mast production during the study may have negated any effect on condition and subsequent reproduction between the 2 study areas. These data suggest that reproductive parameters of wild pigs do not exhibit density-dependence during periods when pig populations are in good condition. © 2012 The Wildlife Society.     

Sanitary Waste Landfill Effects on an Invasive Wild Pig Population

Being opportunistic omnivores, wild pigs (Sus scrofa) readily feed on edible garbage. Given the presence of substantial volumes of edible food waste, large multi-county and regional municipal sanitary waste landfills constitute attractive forage resources for pigs, providing a year-round anthropogenic source of potentially high-quality forage. Our objective was to assess the effects that a large regional landfill has on the local pigs foraging in that facility's waste disposal cells. The landfill, located on the United States Department of Energy's Savannah River Site (SRS) in South Carolina, USA, became operational in 1998 and pigs began foraging there in 2001. By 2009 >100 pigs/night were observed foraging in the landfill, suggesting landfill establishment may have important consequences for population dynamics, public safety, and disease transmission. We evaluated changes in body mass, fetal litter size, numbers of pigs removed, and wild pig-vehicle collisions (WPVCs) before (1980–2000) and after (2001–2019) pigs began foraging in the landfill on SRS. Body mass during the after period increased to a greater extent for pigs in the vicinity of the landfill compared to pigs on the rest of SRS. Fetal litter size increased for pigs in the vicinity of the landfill, whereas it remained unchanged on the rest of SRS. Our density surrogate (number of pigs harvested) increased around the landfill during the after period by 2.9 times, whereas on the rest of the site it only increased by 53%. No WPVCs occurred adjacent to the landfill before 2001, but WPVCs increased along the 2 major roads bordering the landfill after 2001. Effects of sanitary waste landfills on wild pig populations scavenging there can present unique challenges to population management, control, public safety, and disease transmission. Potential approaches to address these challenges could be exclusion fencing to prevent access to the landfill's waste disposal cells or enhanced placement of waste cell covers to reduce access. © 2021 The Wildlife Society.     

Electrophoretic variants of serum transferrin in wild pig populations of Japan

Variants of serum transferrin in Japanese wild pig, Sus scrofa leucomystax, and Ryukyu wild pig, S.s. riukiuanus, of Japan were investigated by using starch gel electrophoresis. Five phenotypes, TfB, BC, C, CX and X, were observed, of which two, TfCX and X, are new variants. Comparison of gene frequency estimates which were calculated for each population showed remarkable geographic differences among several populations of these two subspecies.