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.     

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.     

Taxonomy of wild pigs (Sus) of the Philippines

Native wild pigs of the Philippines are now in grave danger of extinction. Study of available material indicates that three species are present: Sundaland Sus barbatus on Palawan, and two endemic species, Sus philippensis (with three subspecies, one of them here described as new) on Luzon, Mindanao, Basilan, Leyte, Samar, Catanduanes and Mindoro, and Sus cebifroms on Negros, debit and Panay. Specimens from Jolo. Masbale and Bohol presently remain unallocated to species, and may reflect the occurrence of hybridization.     

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.     

Estimating body mass of wild pigs (Sus scrofa) using body morphometrics

Wild pigs (Sus scrofa) are invading many areas globally and impacting biodiversity and economies in their non‐native range. Thus, wild pigs are often targeted for eradication efforts. Age‐ and sex‐specific body measurements are important for informing these eradication efforts because they reflect body condition, resource availability, and fecundity, which are common indicators of population trajectory. However, body mass is often difficult to collect, especially on large individuals that require specialized equipment or multiple people to weigh. Measurements that can be rapidly taken by a single land or wildlife manager on any size wild pig without aid from specialized equipment would be beneficial if they accurately infer wild pig body mass. Our goals were to assess whether morphometric measurements could accurately predict wild pig body mass, and to provide tools to directly input these measures and estimate wild pig body mass. Using linear models, we quantified the relationship between body mass and morphometric measurements (i.e., body length, chest girth, ear length, eye to snout length, hindfoot length, shoulder length, and tail length) from a subset (n = 102) of wild pigs culled at the Mississippi Alluvial Valley, Mississippi, USA. We evaluated separate models for each individual morphometric measurement. We then used the model coefficients to develop equations to predict wild pig body mass. We validated these equations predicting body mass of 1592 individuals collected across eight areas in Australia, Guam, and the USA for cross‐validation. Each developed equation remained accurate when cross‐validated across regions. Body length, chest girth, and shoulder length were the morphometrics that best predicted wild pig body mass. Our analyses indicated it is possible to use the presented equations to infer wild pig body mass from simple metrics.     

Iophenoxic Acid as a Long-Term Marker for Wild Boar

ABSTRACT Chemical markers are increasingly used to investigate consumption of baits used to deliver vaccines, toxicants, and contraceptives. We evaluated whether ethyl-iophenoxic acid (Et-IPA) and propyl-iophenoxic acid (Pr-IPA) can be used as long-lasting systemic bait markers for wild boar (Sus scrofa). We presented captive wild boar with baits treated with either Et-IPA or Pr-IPA at 5 mg/kg (low dose), 10 mg/kg (medium dose), and 20 mg/kg (high dose) of body weight. We collected serum from each boar at 5 time points: 5 days, 3 weeks, 6 weeks, 11 weeks, and 39 weeks following ingestion of iophenoxic acid-treated baits. We detected both Et-IPA and Pr-IPA for ≥39 weeks after ingestion. Throughout the trial, the Et-IPA we found in serum was proportional to the amount eaten. At each time point, animals in the high-dose group had significantly more Et-IPA than animals in the low-dose group. We concluded that both compounds can be used as long-lasting markers in wild boar and that Et-IPA can also be employed as quantitative marker to indicate multiple bait uptake. Both compounds have potential applications in the context of vaccination, fertility, and population control campaigns, where baits are used to deliver pharmaceuticals, and in behavioral studies to establish spatial and temporal patterns of bait uptake.     

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.     

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.     

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.     

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.     

Wildlife genetics and disease: allozyme evolution in the wild boar (Sus scrofa) caused by a swine fever epidemy

Enzyme polymorphism at 42 loci was compared before and after a major epidemy of swine fever in wild boars from northern Vosges (France). No change was observed in the 38 monomorphic loci, but allele frequencies at the phosphoglucomutase locus PGM-2* changed significantly. Possible causes for this observation are discussed, and it appears that PGM-2 locus could be a genetic marker of resistance to this viral disease.     

Influence of methylmalonyl-CoA mutase alleles on resistance to bovine tuberculosis in the European wild boar (Sus scrofa)

An association study was carried out to examine the influence of methylmalonyl-CoA mutase (MUT) polymorphisms on the susceptibility of a well-studied wild boar population from southern Spain to develop bovine tuberculosis (bTB). To this end, we examined polymorphisms at a closely linked dinucleotide microsatellite flanking exon 2 of the MUT gene in 37 wild boars with bTB and 36 non-infected individuals. The microsatellite showed low polymorphism in the studied population, with only three alleles (MUTm-A, MUTm-B and MUTm-C) found, in contrast to the 11 alleles previously reported for domestic pigs. Our case-control study showed that the MUTm-B allele was associated with disease in a dominant pattern (odds ratio = 3.36; 95% CI = 1.05-10.72; P = 0.04), while the MUTm AA genotype appeared to have a protective effect against bTB infection (odds ratio = 4.33; 95% CI = 1.20-14.96; P = 0.02). Interestingly, infected wild boars heterozygous for MUTm AB are at an advantage (11-fold) to contain the systemic spread of the disease when compared to other genotypes, implying that a balanced polymorphism may be present in the population. These results strengthen previous observations regarding the importance of the MUT gene on bTB resistance in wild boars and indicate that polymorphisms at this locus will influence the risk of acquiring and maintaining bTB in the studied population.     

The Balkans and the colonization of Europe: the post‐glacial range expansion of the wild boar,Sus scrofa

Aim We focus on the biogeographical role of the Balkan Peninsula as a glacial refugium and source of northward post‐glacial dispersal for many European taxa. Specifically, we analysed the genetic structure and variation of wild boar (Sus scrofa) samples primarily from Greece, a region that has repeatedly served as a glacial refugium within the Balkan Peninsula. Location Continental Greece, the Aegean island of Samos and Bulgaria. Methods We analysed wild boar samples from 18 localities. Samples from common domestic breeds were also examined to take into account interactions between wild and domesticated animals. Phylogenetic analyses were carried out on a 637‐bp fragment of the mitochondrial DNA control region in 200 wild boar and 27 domestic pigs. The sequences were also compared with 791 Eurasian wild boar and domestic pig D‐loop sequences obtained from GenBank. Results Ninety‐four haplotypes were identified in the European wild boar data set, of which 68 were found in the Balkan samples and assigned to two previously described clades: the E1 European and Near Eastern clades. All of the continental samples clustered in the E1 clade and the samples from Samos fell into the Near Eastern clade, consistent with the island’s proximity to Asia Minor. Intriguingly, 62 novel haplotypes were identified and are found exclusively in the Balkans. Only six haplotypes were shared between wild boar and domestic pigs. Main conclusions Our data reveal numerous novel and geographically restricted haplotypes in wild boar populations, suggesting the presence of separate refugia in the Balkans. Our analyses support the hypothesis of a post‐glacial wild boar expansion consistent with the leading edge model, north and west from modern day Greece, and suggest little maternal introgression of Near Eastern and domestic haplotypes into wild Balkan populations.     

Genome-wide association studies for the number of teats and teat asymmetry patterns in Large White pigs

The number of teats is a morphological trait that influences the mothering ability of the sows and thus their reproduction performances. In this study, we carried out GWASs for the total number of teats and other 12 related parameters in 821 Italian Large White heavy pigs. All pigs were genotyped with the Illumina PorcineSNP60 BeadChip array. For four investigated parameters (total number of teats, the number of teats of the left line, the number of teats of the right line and the maximum number of teats comparing the two sides), significant markers were identified on SSC7, in the region of the vertnin (VRTN) gene. Significant markers for the numbers of posterior teats and the absolute difference between anterior and posterior teat numbers were consistently identified on SSC6. The most significant SNP for these parameters was an intron variant in the TOX high mobility group box family member 3 (TOX3) gene. For the other four parameters (absolute difference between the two sides; anterior teats; the ratio between the posterior and the anterior number of teats; and the absence or the presence of extra teats) only suggestively significant markers were identified on several other chromosomes. This study further supported the role of the VRTN gene region in affecting the recorded variability of the number of teats in the Italian Large White pig population and identified a genomic region potentially affecting the biological mechanisms controlling the developmental programme of morphological features in pigs.     

浙江清凉峰国家级自然保护区野猪空间分布及活动节律

为了解浙江清凉峰国家级自然保护区内野猪(Sus scrofa)的分布及活动节律,2018年3月至2019年2月,我们利用红外相机技术对其进行了网格化监测。在千顷塘和龙塘山区域总计布设109个红外相机监测点,共计调查39 240个相机日。结果表明,在千顷塘区域,野猪倾向于在落叶阔叶林(拍摄率5.33 ±5.64)和针阔混交林(3.75 ±3.46)活动,而在龙塘山区域,则倾向于针阔混交林(4.32 ±5.21);千顷塘与龙塘山区域野猪各月间的日活动差异指数α均存在极显著差异(P < 0.01),冬季的α值高于其他季节;昼行性指数β的平均值分别为0.870和0.768,显著高于理论值13/24(P < 0.01),表明清凉峰的野猪种群具有明显的昼行性特征,且在冬季的活动时间分配较之其他季节更不均匀。通过核密度估计法分析不同季节野猪的日活动节律发现,保护区内野猪春季有晨昏两个活动高峰(08:00-10:00、17:00-19:00),冬季活动高峰出现在午后(13:00-17:00),其他季节无明显活动高峰。本研究有助于加深对野猪华南亚种生态习性的认知,为保护区的野生动物管理工作提供科学依据。