Sus scrofa, Linnaeus, 1758
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https://doi.org/ 10.5281/zenodo.5721014 |
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https://doi.org/10.5281/zenodo.5721114 |
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persistent identifier |
https://treatment.plazi.org/id/038087E8-5534-5624-8BC4-0CA41B2AF4A6 |
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Conny |
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Sus scrofa |
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16. View On
Eurasian Wild Pig
French: Sanglier d’'Eurasie / German: Wildschwein / Spanish: Jabali
Other common names: Wild Boar; Indochinese Pig (bucculentus), Indonesian Banded Pig (vittatus)
Taxonomy. Sus scrofa Linnaeus, 1758 View in CoL ,
Germany.
S. scrofa is the most widespread species of naturally occurring wild pig. Many of the more distinctive regional forms of these animals were originally described as full species, e.g. villatus, cristatus, leucomystax, moupinensis, and meridionalis, respectively from Sumatra, India, Japan, China, and Sardinia. Later and more comprehensive taxonomic reviews have combined many of these taxa into one species, mostly on the recognition that the different forms of S. scrofa formed a stepped cline extending from Western Europe to the Far East and insular South-east Asia. This gradual change in morphological characteristics allowed the combination of the extreme forms on either side of the range ( scrofa and wvittatus) into one species. This species is therefore characterized by significant levels of naturally occurring geographic/genetic variation, duly compounded by anthropogenic interferences through widespread releases (whether deliberate or accidental) of pure-bred, hybrid, and domesticated variants originating from other parts ofits wide range. An astonishingly large number of subspecies have therefore been proposed and recognized in the literature, some of which are clearly invalid. Precise analysis of the likely number of truly recognizable/differentiated subspecies is still a matter of debate and disagreement, given that 4-25 subspecies have been recognized by different authors. Of these, C. P. Groves undertook by far the most comprehensive review when proposing the recognition of at least 16 morphologically distinct populations of S. scrofa on the basis of external as well as craniometric characteristics. His work has since been challenged by P. Genov, who proposed recognition of only four subspecies based on similar craniometric analyses, but these analyses were flawed inasmuch as they did not include some of the most distinct populations of these animals. Nonetheless, Genov merged these subspecies into four broadly geographic groupings, thereby broadly mirroring Groves’s more comprehensive review. These were the WESTERN RACES or the “ scrofa group,” at least six, but possibly as many as eight subspecies ( scrofa , meridionalis, baeticus, majori, algirus, attila, lybicus, and nigripes), but only two (algirus and meriodionalis) have clearly defined ranges; INDIAN RACES or “cristatus group,” three races (dauvidi, cristatus, and affinis), none with precisely defined ranges; EASTERN RACES or “leucomystax group,” possibly up to seven subspecies (sibiricus, ussuricus, coreanus, leucomystax, riukiuanus, tarvanus, and moupinensis), though only three (leucomystax, riukiuanus and taivanus) have clearly defined ranges; and a highly disctinctive SUNDAIC RACE (viltatus), though presumably genetically continuous with cristatus in the northern limits of its range in Indochina. We follow Groves’s taxonomy because of the strength and breadth of his analysis and his use of external characteristics that were not incorporated in Genov’s analysis. However, new (e.g. phylogenetic) data sets are most likely to strengthen the case for recognizing particular additional subspecies, or elevating some currently recognized subspecies to full species, or merging other, currently recognized subspecies. Groves has questioned whether his subspecies are all variants of one species or a complex of several different species, and has recently proposed the elevation of both vitattus and moupinensis subspecies to full species status. Of these, vittatus is more easily comprehensible, being morphologically and geographically distinguishable as the so-called “Indonesian Banded Pig,” occurring throughout the distal limits of S. scrofa’s range in South-east Asia, whereas S. moupinensis is apparently confined to Myanmar, Indochina, and south-eastern China (Fujian), and therefore also includes the problematic Indochinese Pig (S. bucculentus) from the Annamite Mountains. The taxonomic identity of S. bucculentus remains unclear. Since its description in 1892 by Heude, based on two skulls from Vietnam, only one skull of similar shape and size as the original two has been reported, from Laos. However, reexamination of the skull dimensions of the type specimens and phylogenetic studies suggest that S. bucculentus might not be a distinct species, but a geographically restricted variant of S. scrofa . The possibility that S. bucculentus might be a synonym of S. scrofa is supported by reports from local informants that do not mention facial warts. Warts would be expected if indeed S. bucculentus was more closely related to other South-east Asian warty pigs of the subgenus Euhys. Recent studies have made it more likely that S. bucculentus will be merged with a taxon closelyaffiliated to or part of S. scrofa . As if to complicate matters, Groves has also recently proposed recognition of two more species, namely S. chirodontus described by Heude in 1888 from south-central China (including Kienté, Ningkua, Zhejiang, Shaanxi, Anhui, and also Korea), and S. ussuricus described also by Heude in 1888 from Heilongjiang and far eastern China and Russia. Similarly sharp boundaries between various other mainland Asia subspecies do not exist, especially given evidence of hybridization between salient forms (e.g. davidi and cristatus). However, until these races are formally described and elevated, we retain the existing taxonomy for S. scrofa . We keep subspecies coreanus for now as it is distinct from wussuricus, but note that it was recently proposed for inclusion in moupinensis. Nineteen subspecies are recognized.
Subspecies and Distribution.
S. s. affinisGray, 1847 — SIndiaandSriLanka.
S. s. coreanusHeude, 1897 — KoreanPeninsula.
S. s. eristatusWagner, 1839 — HimalayasStoCIndiaandEtoIndochina (NoftheKraIsthmus).
S. s. majoriDeBeaux & Festa, 1927 — C & SItalianPeninsula.
S. s. moupinensisMilne-Edwards, 1871 — China, StoVietnamandWtoSichuan.
S. s. sibiricusStaffe, 1922 — MongoliaandTransbaikal (S & EofLakeBaikal).
S. s. tawvanusSwinhoe, 1863 — Taiwan.
S.s.vittatusBoie,1828—MalayPeninsula,SoftheIsthmusofKra,theoffshoreislandsofTerutaiandLangkawi,Sumatra,RiauArchipelago,Java,Bali,andarangeofsmallerislandsaroundthese,includingBabi,Bakong,Batam,Bawean,Bengkalis,Bintan,Bulan,Bunguran,Cuyo,Deli,Durian,Enggano,Galang,Jambongan,Karimon(RiauIs),Kundur,Lagong,Laut,Lingga,Lingung,Mapor,MoroKecil,NorthPagai,Nias,Panaitan,Payong,Penang,Pinie,Rupat,Siantan,Siberut,Simeulue,Singkep,Sugi,SugiBawa,Telibon,Tinggi,Tuangku,andtheTambelanIs.ThisspecieswasoriginallypresentfromtheBritishIsintheextremeW,throughEurasiafromSScandinaviatoSSiberia,extendingasfarEasKoreaandJapan,andSEintosomeoftheSundaIsandTaiwan.IntheSthespeciesrangedalongtheNileValleytoKhartoum,andNoftheSaharainAfrica,moreorlessfollowingthecontinentalcoastsof S, s, and SE Asia. Within this range it was absent only from extremely dry deserts, e.g. the driest regions of Mongolia and in China W of Sichuan; and alpine zones, such as the high altitudes of Pamir and Tien Shan. In recent centuries, the range of S. scrofa has changed dramatically because of hunting and changes in available habitat. The species disappeared from the British Is in the 17" century, from Denmark in the 19" century, and was greatly reduced in range and numbers in the 20" century from areas as distant as Tunisia, Sudan, Germany, and Russia. Following these severe declines, there were some slight population recoveries in Russia, Italy, Spain, and Germany in the mid-20™ century, and natural and assisted range expansions in Denmark and Sweden. The species has also been inadvertently reintroduced in various locations in the Great Britain via escapees of mixed origin from commercial farming enterprises. Ex-S. scrofa stocks also occur as introduced feral populations in various other parts of the world, including Australia, New Zealand, the eastern Malay Archipelago, and in North, Central, and South America. In all of these areas they are now generally recognized as a major pest
Descriptive notes. Head-body 90-200 cm, tail 15-40 cm, shoulder height 55-110 cm; weight 44-320 kg. This is a moderate to large pig with a relatively short muzzle and no facial warts. The species is sexually dimorphic, with females about 80% the size of males. Size varies significantly between subspecies. Generally speaking, S. scrofa follows Bergmann’s Rule, with smaller animals nearer the tropics and larger, smaller-eared ones in the north ofits range. The coatis coarse and bristly, and varies in color from brown to almost black, usually turning grayish with age. There are great regional differences in color, and nearly white animals are known from central Asia. Several subspecies have dense underwool. The face, cheeks, and throat are slightly grizzled with whitish hairs, becoming distinctly white or forming white bands in some subspecies. The back is rounded and the legs are relatively long, especially in northern subspecies. Young are born generally brown with a pattern of longitudinal darker brown stripes, known aslivery, along their torso. This pattern fades between the second and sixth month, and the juveniles reach adult coloration at one year of age. The head is long and pointed, without an obvious beard, warts, or facial tufts. The upper canines form tusks that curve out and upwards. The lower canines are kept sharp by rubbing against the upper canines. These canines measure about 20 cm in adult males, and in exceptional cases even 30 cm. In females they are smaller. There is significant geographic variation in S. scrofa . WesTERN RACES: The nominate subspecies scrofa has an adult male skull length between 36-3 cm and 40-6 cm, which further increases towards the border ofits range with the subspecies attila. The species is dull to dark brown or olive-gray, with copious dark-gray or red-brown underwool, and a noticeable mane, which is often long and thick. Bodyweight in scrofa varies significantly from 54 kg to over 200 kg in males, with sows being quite a bit smaller (44.6-61. 4 kg). Towards Spain and Italy body size decreases gradually. In northern Spain, the mean body weight of 637 mature males and females was 74-3 kg and 55-3 kg, respectively. The mean head and body lengths of males and females were 154-4 cm and 142-2 cm, respectively. The subspecies baeticus in southern Spain and meridionalis in the islands of Sardinia and Corsica are significantly smaller than scrofa , with mean skull lengths for males between 30-8 cm and 32-7 cm. These similar looking subspecies are colored a dull olive-fawn, with sparse underwool, and mostly lacking a mane. There is obvious clinal variation from north-western Europe to southern Spain, and it is unclear where the boundary between subspecies scrofa and baeticus is. In central and southern Italy, the subspecies major: is apparently smaller than scrofa , with a higher and wider skull. Since the 1950s, it has hybridized extensively with introduced scrofa populations, which likely obscures morphological differences. Farther south, in northern Africa, the subspecies algirus is like scrofa but has smaller teeth and a broader occiput. The coat of this subspecies is black with yellowish or reddish tips, dark brown underwool, and not much of a mane. Subspecies attila is very large, with skull length in males over 45 cm. It has relatively small teeth, but M,is long, always over 4 cm. Subspecies attilais usually pale yellow-gray, with hair tips long and straw-yellow, copious brown underwool, and a long mane that extends to the loins. Recent information suggests that the subspecies is less distinct than previously thought and might overlap in size as well as chromosomal arrangement with scrofa . Subspecies lybicus is small, pale and almost maneless. Subspecies nigripes is a pale-colored subspecies with dark legs, which are usually paler behind, a nearly white face, and no mane. It has a very broad skull. Weights of male wild pigs from present-day Uzbekistan and southern Kazakhstan are given as 220-240 kg. Like subspecies scrofa, race nigripes has 36 chromosomes, not the 38 that are usual for the species, but the translocation is different. EASTERN RACES: sibiricus is a fairly small pig with a relatively short face (short nasals and palate) compared to similar sized pigs. It has a very high skull with broad occiput. It also stands out for the shape ofits lacrimal bone (as measured by the proportion between suture height of the lacrimal bone at the orbit and its lower suture length), which is 1-0 for males (n = 7) and 0-87 for females (n = 4). Subspecies ussuricus is the largest of S. scrofa , with male wild pigs often weighing over 300 kg. It has a low-crowned skull and thick pelage, which is yellowish-gray in winter and black in summer when the long, pale hair tips have worn off. Subspecies ussuricus has black legs, sharply paler on the posterior surfaces. The face is black and has a clear mouth-gonion band. Initially, pigs from the Korean Peninsula had been included in race ussuricus , but their small size and genetic as well as morphological similarity to race moupinensis makes that affinity less likely. We presently retain this as a distinct subspecies coreanus, but recognize that it might well be included in moupinenss. Subspecies leucomystax is a smallish, short-legged, yellow-brown pig, with virtually no mane. There is a neat cline of diminishing size from north to south, but this apparently doesn’t warrant further division of this subspecies. The island race riukiuanus is by far the smallest subspecies. On the basis of a small data set, there appears to be no sexual size difference; three males with third molars in wear averaged 26-3 cm, and three females 26-1 cm in “profile length,” which presumably equals greatest skull length. Recent phylogenetic studies have shown that this subspecies is more closely related to the mainland China form than to leucomystax from the main islands ofJapan. This is also confirmed by studies of crania and mandibles, which are quite distinct from leucomystax. Subspecies riukiuanus is a prime candidate to be recognized as a full species. Race taivanus from Taiwan is a small black pig with markings on the side of the snout, as judged from camera trap pictures. Measurements of mandibles show considerable overlap between taivanus and leucomystax, but with riukiuanus being quite distinct. The occiput in taivanus is shorter than in leucomystax, with little overhang. Subspecies moupinensis is a fairly small, yellowish (in south of range) or darker (in north), short-maned pig with a broad, high-crowned skull, from most of China and Vietnam. Elevation to full species status was recently proposed for this taxon. SOUTH ASIAN RACES: The subspecies of India, Burma, and western Thailand, cristatus is long-maned, with a coat thatis brindled black, unlike race david : (see below). Subspecies cristatus is more lightly built than European subspecies, and it has a larger and more pointed head, and smaller and more pointed ears. The plane of the forehead is straight, whereas it is concave in the European subspecies. Subspecies cristatus differs little from moupinensis, but has a much longer mane, which extends to the rump. Itis darker than moupinensis. Race davidi is a small, light brown pig, with a long thick mane, and without any black on the legs. Weights of wild pigs from Tajikistan, which might be this subspecies, were reported as 74-144 kg, and occasionally up to 158 kg for males, and 71-123 kg for females. This subspecies belongs to the low-crowned pigs of the western part of S. scrofa’ distribution range, rather than to the eastern pigs of India, China, and the rest of east and South-east Asia. Race affinis of southern India and Sri Lankais larger than cristatus, overall black or occasionally dark brown. MALAYAN RACE: Sometimes referred to as the Indonesian Banded Pig, of peninsular Malaysia and western Indonesia is a small, lowcrowned, short-faced pig with very sparse pelage. It is generally brown or agouti colored, with black legs, and typically has a distinct whitish band extending from either side of the snout to the jowls (hence “banded pig”) and a distinct mane. It has very sparse body hair and no underwool. There is a huge range of size and color throughout this region, but it is so sporadically distributed, with intermediates between the extremes, that it is impossible to divide it up. The species has shorter nasals and narrower occiput than race cristatus . It also stands apart from all other S. scrofa subspecies in the shape of the lacrimal bone and the shape of the rear end of the hard palate.
Habitat. S. scrofa is an ecologically very adaptable species, occurring in habitats varying from closed natural and planted forests to open scrublands with some cover. In Europe, the species occurs in agricultural landscapes, as well as riverine and mountainous forests, where it reachesits highest densities in oak-dominated forests. In South-east Asia, S. scrofa is found in mature forests, secondary forests, gardens, and plantations. It can reach very high densities in dipterocarp forests during times of mastfruiting. S. scrofa can cause considerable damage to agriculturalfields. The animals generally avoid open fields but do enter them readily when crops are taller and thus provide cover.
Food and Feeding. S. scrofa is a typical omnivorous species. They eat almost anything they come across, including grass, nuts, berries, carrion, roots, tubers, refuse, insects, and small reptiles. They are also known to prey on young deer and lambs, and, in India, have been observed to prey on Chital (Axis axis) and to forcibly appropriate fresh kills from Leopards (Panthera pardus). Vertebrate prey may constitute an important part of the species’ diet in some areas, though studies in Spain revealed that prey items (mostly birds and crayfish) made up only 4% of their diets. Snails and terrestrial arthropods were frequently found but take up less volume. The species causes considerable damage to croplands, with damage to permanent grassland more frequent and more severe than damage to annual crops. S. scrofa is preyed on by a range of species, including Gray Wolves (Canis lupus), Dholes (Cuon alpinus), Tigers (FP. tigris), Leopards, Eurasian Lynxes (Lynx lynx) and some larger reptiles, such as crocodiles and pythons (Python spp.).
Breeding. S. scrofa has a gestation period of 112-130 days. Litters of 5-9 are most common, although both smaller and larger do occur. Piglets weigh 750-1000 g at birth. Just prior to giving birth, the sows leave their social groups and construct well-developed nests in which to give birth, or farrow, a process usually lasting 2-3 hours. The sow and piglets remain in, or close to, the nest for 4-6 days before rejoining their natal family groups, after which piglets will suckle other lactating sows in the group. Young are weaned at 3-4 months, and they will begin to eat solid foods, such as worms and grubs, after about two weeks. The young usually reach sexual maturity at 18 months. Breeding occurs year-round in the tropics, although in more temperate zones the young are born primarily in the spring. In the Ukraine, about 80% of S. scrofa females reproduce annually. Their fertility rate is 7-21+ 0-26 piglets, but during the first year of their life more than 50% of the piglets die. Animals can live over 20 years in the wild, but populations are dominated by younger animals. For example, a Eurasian wild steppe population comprised 58:6% juveniles (the first year oflife), 14-3% yearlings (the second year), 11:5% adult males, and 15-6% adult females. If surprised or cornered, a boar (and particularly a sow with her piglets) can and will defend itself and its young with intense vigor. The male lowers its head, charges, and then slashes upward with his tusks. The female, whose tusks are notvisible, charges with her head up, mouth wide, and bites.
Activity patterns. Activity of S. scrofa varies geographically but seems to be concentrated between dusk and dawn, and especially between 20:00 h and 24:00 h and around 05:00 h, with a primary resting period at night and a briefer rest during the early afternoon. In areas with high hunting pressure, a shift to nearly exclusive nocturnal activity has been observed. S. scrofa rests in tight groups with bodily contact. The resting places, used several times before being abandoned, are made of troughs lined with leaves and branches. Wallowing is a favorite activity. After wallowing, the Eurasian Wild Pig rubs against trees and bushes, an activity that serves as a territorial marker.
Movements, Home range and Social organization. Densities of S. scrofa vary widely depending on habitat quality and mortality rates. To give some examples,in Italy, densities are generally about 3-5 ind/ 100 km?, in Spain they are about 0-7-16-3 ind/ 100 km? and in Switzerland they are about 10 ind/ 100 km ®. In Malaysia, S. scrofa locally reaches population densities of 47 ind/km? at least during times of high food availability. Pig biomass at such times was estimated at between 1346 kg /km?*and 1837 kg /km*. A review of 54 density studies in western Eurasia showed that in the geographical span of 37-60° N, the population densities of Eurasian Wild Pigs declined by three orders of magnitude. Mean January temperature and vegetative productivity were the most important factors explaining the biogeographical variation in population densities of S. scrofa , with the impact of temperature being stronger than that of productivity. The presence of Gray Wolves had a weak limiting effect on population densities of wild pigs at the biogeographical scale. S. scrofa generally occurs in maternal families or sounders averaging 20 individuals, but up to 100 individuals have been reported, albeit perhaps in temporary associations. Adult males are usually solitary outside of the breeding season. Group structure changes with the coming and going of farrowing females, the migration of maturing males (usually when they reach around four years of age) and the arrival of unrelated sexually active males. Pigs are excellent swimmers, and have been documented swimming between offshore islands up to 7 km apart.
Status and Conservation. Classified as Least Concern on The IUCN Red List, except for the subspecies riukiuanus, which has sometimes been listed separately as Vulnerable. The species is abundant in many parts of its range, though populations have been severely reduced and fragmented in places where hunting intensity is high (for example, in eastern and south-eastern Asia). Although there is no global population estimate, numbers can be high in many places. At a global level, there are no major threats to the species. However, there are many threats at a more local level, principally habitat destruction and hunting pressure, either for food, sport, or in reprisal for crop damage. In some places, genetic contamination through interbreeding with free-ranging domesticated or feral pigs is also a threat. Areas of special concern include the Ryukyu Islands, south Japan, where the endemic subspecies riukiuanus is internationally recognized as being seriously threatened throughout its extremely restricted and discontinuous range. It is ostensibly protected by the Japanese Government as a national monument. Nonetheless, it is widely hunted for sport and in reprisal for crop damage, and local governmental authorities even pay bounties to farmers for these animals. In various places in Indonesia, most notably in Java, attempts have been made in the past to eradicate wild pigs altogether by means of organized shooting parties and poisoning campaigns. However, despite many thousands of wild pigs being destroyed in this way,it is clear that this has had little lasting effect on these animals. Wild pigs are also susceptible to a variety of highly contagious diseases that can decimate their populations. Such catastrophic crashes were reported from Sri Lanka in 1989 due to swine fever, Honshu Island, Japan in 1877, possibly because of hog cholera, and the Iriomote Islands between 1976 and 1980, caused by severe skin disease tentatively identified as sarcoptic mange. The traditional practice of rearing “domestic” pigs in semi-wild conditions has resulted in their hybridizing with the wild populations. Although introduced feral pigs are almost invariably regarded as major pests, some seemingly “ancient” breeds are of particular scientific interest and/or socio-economic importance to local peoples. Most prominent among these are the diminutive wild pigs of the Andaman and Nicobar Islands.The Andaman Island suids include the world’s smallest freeranging wild pigs (with the exception of Pygmy Hogs, Porcula salvania), which occur in two distinct “long-snouted” and “short-snouted” morphotypes, and which constitute one of the most important food resources for the few remaining indigenous Onge, Jarawa, and Sentinilese tribal societies. Whilst the Andamanese tribals are traditionally hunter-gatherers, dependent on the continued hunting of the wild pigs and other species, both wild and domestic pigs are of the greatest cultural importance to the Shompen tribal people of the Nicobar Islands, who not only domesticate pigs in large numbers, but have evolved one of the most complex “human-pig” cultures found anywhere in the in the world. A similar situation exists in eastern Indonesia, Papua, and a range Micronesian and Macronesian islands, where domesticated S. scrofa (as well as domesticated S. celebensis ) play a very important cultural role.
Bibliography. Acevedo et al. (2006), Albayrak & Inci (2007), Appelman (1931), Appolonio et al. (1988), Asada et al. (2001), Behera & Gupta (2007), Chhangani & Mohnot (2004), Ellerman & Morrison-Scott (1951), Endo, Hayashi, Sasaki et al. (2000), Endo, Hayashi, Yamazaki et al. (2002), Endo, Kurohmaru et al. (1998), Endo, Maeda et al. (1998), Fistani (1996), Francis (2008), Galbreath (2007), Genov (1987, 1992, 1994, 1999), Gimenez-Anaya et al. (2008), Giuffra et al. (1999), Groves (1981, 2007), Groves & Oliver (2008), Hebeisen et al. (2008), Ickes (2001), Jayson (1995), Kelm (1939), Kodera (2005), Kumar Chhangani (2002), Li Chonggi et al. (2005), Markina et al. (2004), Massei et al. (1997a, 1997b), Meijaard et al. (2002), Melis et al. (2006), Mitchell (2002), Mona et al. (2007), Oliver & Leus (2008), Oliver, Brisbin & Takahashi (1993a, 1993b), Oliver, Groves & Cox (1993), Pei (2006), Robins et al. (2006), Ruhe et al. (2007), Russo et al. (1997), Santos et al. (2006), Schley & Roper (2003), Schley et al. (2008), Spagnesi & de Marinis (2002), Thurfjell et al. (2009), Volokh (2002a, 2002b), Watanobe, Ishiguro & Nakano (2003), Watanobe, Okumura et al. (1999), Wilcox & Van Vuren (2009), Zhang Baoweiet al. (2008).
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