Wild boar
The wild boar, also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The species is now one of the widest-ranging mammals in the world, as well as the most widespread suiform. It has been assessed as least concern on the IUCN Red List due to its wide range, high numbers, and adaptability to a diversity of habitats. It has become an invasive species in part of its introduced range. Wild boars probably originated in Southeast Asia during the Early Pleistocene and outcompeted other suid species as they spread throughout the Old World.
, up to 16 subspecies are recognized, which are divided into four regional groupings based on skull height and lacrimal bone length. The species lives in matriarchal societies consisting of interrelated females and their young. Fully grown males are usually solitary outside the breeding season. The wolf is the wild boar's main predator in most of its natural range except in the Far East and the Lesser Sunda Islands, where it is replaced by the tiger and Komodo dragon respectively. The wild boar has a long history of association with humans, having been the ancestor of most domestic pig breeds and a big-game animal for millennia. Boars have also re-hybridized in recent decades with feral pigs; these boar–pig hybrids have become a serious pest wild animal in the Americas and Australia.
Terminology
As true wild boars became extinct in Great Britain before the development of Modern English, the same terms are often used for both true wild boar and pigs, especially large or semi-wild ones. The English boar stems from the Old English bār, which is thought to be derived from the West Germanic bair, of unknown origin. Boar is sometimes used specifically to refer to males, and may also be used to refer to male domesticated pigs, especially breeding males that have not been castrated.Sow, the traditional name for a female, again comes from Old English and Germanic; it stems from Proto-Indo-European, and is related to the Latin sus and Ancient Greek hus, and more closely to the New High German Sau. The young may be called piglets or boarlets.
The animals' specific name scrofa is Latin for 'sow'.
Hunting
In hunting terminology, boars are given different designations according to their age:| Designation | Age | Image |
| Squeaker | 0–10 months | |
| Juvenile | 10–12 months | |
| Pig of the sounder | Two years | |
| Boar of the 4th/5th/6th year | 3–5 years | |
| Old boar | Six years | |
| Grand old boar | Over seven years |
Taxonomy and evolution
studies indicate that the wild boar originated from islands in Southeast Asia such as Indonesia and the Philippines, and subsequently spread onto mainland Eurasia and North Africa. The earliest fossil finds of the species come from both Europe and Asia, and date back to the Early Pleistocene. By the late Villafranchian, S. scrofa largely displaced the related S. strozzii, a large, possibly swamp-adapted suid ancestral to the modern S. verrucosus throughout the Eurasian mainland, restricting it to insular Asia. Its closest wild relative is the bearded pig of Malacca and surrounding islands.Subspecies
, 16 subspecies are recognised, which are divided into four regional groupings:- Western: Includes S. s. scrofa, S. s. meridionalis, S. s. algira, S. s. attila, S. s. lybicus, S. s. majori and S. s. nigripes. These subspecies are typically high-skulled, with thick underwool and poorly developed manes.
- Indian: Includes S. s. davidi and S. s. cristatus. These subspecies have sparse or absent underwool, with long manes and prominent bands on the snout and mouth. While S. s. cristatus is high-skulled, S. s. davidi is low-skulled.
- Eastern: Includes S. s. sibiricus, S. s. ussuricus, S. s. leucomystax, S. s. riukiuanus, S. s. taivanus and S. s. moupinensis. These subspecies are characterised by a whitish streak extending from the corners of the mouth to the lower jaw. With the exception of S. s. ussuricus, most are high-skulled. The underwool is thick, except in S. s. moupinensis, and the mane is largely absent.
- Indonesian: Represented solely by S. s. vittatus, it is characterised by its sparse body hair, lack of underwool, fairly long mane, a broad reddish band extending from the muzzle to the sides of the neck. It is the most basal of the four groups, having the smallest relative brain size, more primitive dentition and unspecialised cranial structure.
Domestication
DNA evidence from sub-fossil remains of teeth and jawbones of Neolithic pigs shows that the first domestic pigs in Europe had been brought from the Near East. This stimulated the domestication of local European wild boars, resulting in a third domestication event with the Near Eastern genes dying out in European pig stock. Modern domesticated pigs have involved complex exchanges, with European domesticated lines being exported in turn to the ancient Near East. Historical records indicate that Asian pigs were introduced into Europe during the 18th and early 19th centuries. Domestic pigs tend to have much more developed hindquarters than their wild boar ancestors, to the point where 70% of their body weight is concentrated in the posterior, which is the opposite of wild boar, where most of the muscles are concentrated on the head and shoulders.
Synonymous species
The Heude's pig, also known as the Indochinese warty pig or Vietnam warty pig, was an alleged pig species found in Laos and Vietnam. It was virtually unknown and was feared extinct, until the discovery of a skull from a recently killed individual in the Annamite Range, Laos, in 1995. Subsequent studies indicated that Sus bucculentus was not a valid taxon. As of 2022 the Mammal Diversity Database included it in Sus scrofa.Description
The wild boar is a bulky, massively built suid with short and relatively thin legs. The trunk is short and robust, while the hindquarters are comparatively underdeveloped. The region behind the shoulder blades rises into a hump and the neck is short and thick to the point of being nearly immobile. The animal's head is very large, taking up to one-third of the body's entire length. The structure of the head is well suited for digging. The head acts as a plough, while the powerful neck muscles allow the animal to upturn considerable amounts of soil: it is capable of digging into frozen ground and can upturn rocks weighing. The eyes are small and deep-set and the ears long and broad. The species has well developed canine teeth, which protrude from the mouths of adult males. The medial hooves are larger and more elongated than the lateral ones and are capable of quick movements. The animal can run at a maximum speed of 40 km/h and jump at a height of.Sexual dimorphism is very pronounced in the species, with males being typically 5–10% larger and 20–30% heavier than females. Males also sport a mane running down the back, which is particularly apparent during autumn and winter. The canine teeth are also much more prominent in males and grow throughout life. The upper canines are relatively short and grow sideways early in life, though they gradually curve upwards. The lower canines are much sharper and longer, with the exposed parts measuring in length. In the breeding period, males develop a coating of subcutaneous tissue, which may be thick, extending from the shoulder blades to the rump, thus protecting vital organs during fights. Males sport a roughly chicken egg–sized sac of unclear function near the opening of the penis that collects urine and emits a sharp odour.
Adult size and weight is largely determined by environmental factors; boars living in arid areas with little productivity tend to attain smaller sizes than their counterparts inhabiting areas with abundant food and water. In most of Europe, males average in weight, in shoulder height and in body length, whereas females average in weight, in shoulder height and in body length. In Europe's Mediterranean regions, males may reach average weights as low as and females, with shoulder heights of. In the more productive areas of Eastern Europe, males average in weight, in shoulder height and in body length, while females weigh, reach in shoulder height, and reach in body length. In Western and Central Europe, the largest males weigh and females. In Northeastern Asia, large males can reach brown bear-like sizes, weighing and measuring in shoulder height. Some adult males in Primorsky Krai and Manchuria have been recorded to weigh and measure in shoulder height. Adults of this size are generally immune from wolf predation. Such giants are rare in modern times, as past overhunting has prevented animals from attaining their full growth.
The winter coat consists of long, coarse bristles underlaid with short brown downy fur. The length of these bristles varies along the body, with the shortest being around the face and limbs and the longest running along the back. These back bristles form the aforementioned mane prominent in males and stand erect when the animal is agitated. Colour is highly variable; specimens around Lake Balkhash are very lightly coloured, and can even be white, while some boars from Belarus and Ussuriland can be black. Some subspecies sport a light-coloured patch running backward from the corners of the mouth. Coat colour also varies with age, with piglets having light brown or rusty-brown fur with pale bands extending from the flanks and back.
The wild boar produces a number of different sounds which are divided into three categories:
- Contact calls: Grunting noises which differ in intensity according to the situation. Adult males are usually silent, while females frequently grunt and piglets whine. When feeding, boars express their contentment through purring. Studies have shown that piglets imitate the sounds of their mother, thus different litters may have unique vocalisations.
- Alarm calls: Warning cries emitted in response to threats. When frightened, boars make loud huffing sounds or emit screeches transcribed as.
- Combat calls: High-pitched, piercing cries.
Pigs are one of four known mammalian taxa which possess mutations in the nicotinic acetylcholine receptor that protect against snake venom. Mongooses, honey badgers, hedgehogs, and pigs all have modifications to the receptor pocket which prevents the snake venom α-neurotoxin from binding. These represent four separate, independent mutations.