WILD BOARS: CHARACTERISTICS, BEHAVIOR AND REPRODUCTION

WILD BOARS

Wild boars (Sus scrofa) and domesticated pigs (Sus scrofa domesticus) are the same species, with the latter technically being a subspecies of the former. They can interbreed and produce viable offspring. Physically, domesticated pigs are fatter and have a shorter snout than their cousins. However, feral pigs that descended from escaped domesticated pigs develop long snouts and sleek bodies like wild boars.

Wild boars and pigs are relatives of wart hogs in Africa. Widely distributed across Europe, Asia and the United States, wild boar almost never threaten humans except when they are hunted or cornered. They spend much of their time grunting and scratching and rooting for tubers and roots. The are three kinds of wild boars: 1) true wild pigs; 2) feral pigs (descendants of escaped domesticated pigs that went wild); and 3) crosses between the two. [Source: James Tabor, Smithsonian magazine]

Most European wild pigs are feral pigs or crosses who have lived in the wild for so long the difference between them and true wild pigs is very slight. Over time European wild pigs physical characteristics have achieved almost total genetic dominance in the crossbreeds.Wild boars are found throughout Asia, particularly in primary and secondary forests and along the edges of agricultural areas. Asian wild boars are smaller than their Eurasian cousins. They average around 100 kilograms. Some weigh around 50 kilograms. By contrast, Siberian boars can reach 300 kilograms.

The maximum known lifespan of wild boars in the wild is nine to 10 years. On average, they only live for a few years. A member of the subspecies Ryukyu wild boar (Sus scrofa riukiuanus) of the Ryukyu islands of Japan reportedly lived 27 years in captivity. Mortality for both male and female boars in the wild is greatly affected by hunting. Where sport hunting is practiced, older males are often taken in greater numbers because they are considered trophy animals. This can skew longevity numbers towards lower lifespans for males. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

Wild boars are commonly referred to as wild pigs, wild hogs, or feral swine. They are also sometimes called Eurasian wild boars and, in North America, razorbacks. In hunting terminology, different stages of a wild boar's life have different names: 1) squeaker (0–10 months); 2) juvenile (10–12 months); 3) sounders (one to two years old); 4) boar of the 4th/5th/6th year (3–5 years); 5) old boars (six years); and 6) grand old boar (Over seven years). Hogs is the term used by scientists and people in the livestock industry to describe the family of animals that includes pigs and boars. The term pig is used to describe a young hog. A male hog is called a boar. A female is called a sow. Young are called piglets.

Wild Boar Habitat and Range

range of wild boar: reconstructed range (green) and introduced (blue)

Wild boars are a cosmopolitan species that have a worldwide distribution. They originated in Europe and Asiam where they continue to be common, and now inhabit every continent except Antarctica. They were widely introduced to the Americas, beginning with Christopher Columbus's second voyage in 1493, and Australia, in 1788, and are considered an invasive species in the southeastern United States, California, Brazil, Argentina, New Guinea and northern and eastern Australia.

Wild boars are vary adaptable animals and can be found in a variety of habitats and climates. They live in temperate areas and tripical areas in savanna grasslands and forests. They can also be found in wetlands such as marshes and swamps as well as agricultural areas and areas near rivers and water bodies. The main places there are not found are very dry deserts — but can be found in steppes and semi-arid regions — and very cold northern latitudes. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

Wild boars favor wooded forests, grassy savanna areas, shrublands and marshy swamplands. They require a nearby water source, and dense vegetation to protect and conceal them from predation. Wild boars rarely venture more than eight kilometers (five miles) from the place of their birth unless they are forced to by food shortages. They prefer habitats in moist bottomland, flood plains, marshes, sloughs and creeks because of the availability of mud for wallowing and food they like. In places that experience harsh winter temperatures and snow, population densities may be limited by food sources. Deeper snows and frozen ground inhibit their ability to forage for roots and foliage.

Wild Boar History and Evolution

suid family tree

The ancestors of wild boars and pigs first evolved in India around 30 million years ago and later spread throughout Europe, Central Asia and Africa. They spread to the Americas and died out and then were reintroduced after Columbus's arrival. In prehistoric times people found that young boars could be kept in the villages and bred. As time went on domesticated wild boars evolved into domesticated pigs.

Suidae — whose members are called suids — is a family of artiodactyl mammals which includes wild boars, pigs, wart hogs of Africa and other wild pig-like animals such as the babirusa of Sulawesi, Indonesia and the pygmy hog of the Himalayan foothills. The earliest fossil suids date from the Oligocene period (34 to 23 million years ago). in Asia. Their descendants reached Europe during the Miocene (23 to 5.3 million years ago). Fossils species of prehistoric species show adaptations to a wide range of different diets — from strict herbivores to possible carrion-eating. [Source: Wikipedia +]

MtDNA data indicates that wild boar originated from islands in Southeast Asia such as Indonesia and the Philippines, and subsequently spread onto mainland Eurasia and North Africa.[8] The earliest fossil finds of the species come from both Europe and Asia, and date back to the Early Pleistocene (2.6 million to 773,000 years ago). By at least a million years ago modern wild boars (S. scrofa) largely displaced the related S. strozzii, a large, possibly swamp-adapted suid ancestral to the modern Javan warty pig (S. verrucosus) throughout the Eurasian mainland, restricting it to insular Asia. The closest wild relative of the wild boar is the bearded pig of Malacca and other islands in Indonesia. +

Wild Boar Characteristics and Size

Adult wild boars generally range in weight from 45 to 66 kilograms (100 to 145 pounds), stand about 0.8 to one meter (2½ to 3 feet) at the shoulder and range in length from 1.2 to 1.5 meters (4 to 5 feet), including their tails. Big ones can reach a weight of 272 kilograms (600 pounds) and have a head and body length of 2.4 meters (7.9 feet). Older boars in some areas have an average weight of 150 kilograms (330 pounds). The average basal metabolic rate of wild boars is 104.1500 W cubic centimeters of oxygen per gram per hour.Their average basal metabolic rate is 104.15 watts. Sexual Dimorphism (differences between males and females) is present: Males are larger than females, with the size difference becoming more apparent as the animals age.. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

The biggest wild boar ever recorded was named Hogzilla, weighing in at 362 kilograms (800 pounds) and measuring between 2.1 and 2.6 meters (6.9 and 8.6 feet) long. Hogzilla was a hybrid of a wild boar and a Hampshire domestic pig. Another notable, and possibly larger, boar was "Hog Kong," estimated to weigh 517 kilograms (1,140 pounds).

emergence of wild pigs, followed by the genetic divergence between boars and pigs and the domestication of pigs

Covered by grayish, brownish or blackish hair and coarse bristles, wild boars have tusks, straight tails, elongated snouts and erect ears. Domesticated pigs by contrast have little body hair. floppy ears, a spiralling tail and small or no tusks. Adult wild boars have a thick, coarse coat of hair covering their bodies. Depending on their geographic location, they can have a speckled or solid fur color. They may also have longer bristly hairs that grow down the middle of their backs.

Wild boars have bulky shoulders and a body that tapers off towards their hind quarters. Their tails measure 21 to 38 centimeters (8.3 to 15 inches), and their ears are 24 to 26 centimeters (9.4 to 10.2 inches) long. Wild boars have large muscles on their chest and the back of their necks which help them root (dig up food in the ground with their snout). Their long snout helps them locate food when they root. Amazingly adaptable, wild boars in northern regions have developed thick coats of fur and eat enough to amass layers of insulating fat so they can survive cold winters. The short legs of wild boars make it difficult for them get around in deep snow. Thus they are rarely found in places with deep snow.

Both male and female boars have tusks in the mandible and maxilla that are sharpened by rubbing against each other. Male tusks grow to up to 15 centimeters (six inches)in length. Wild boars have two sets of tusks (canines). Their upper ones typically measure five to 10 centimeters (2 to 4 inches) and are generally larger than their lower ones. Their upper tusks are usually visible even when their mouth is closed. Their dental formula is I 3/3, C 1/1, P 4/4, meters 3/3 = 44. The more fearsome set of tusks, on the upper jaw, is used primarily to push through the thornbush. The sharper, small tusks are immediately below on the lower jaw. These are used in defense against attackers and in fights against other wild boars.The upper tusks are sometimes called whetters. The tusks grow as long as a wild boar lives. The lower tusks, which jut upwards at an angle, are kept sharp and dangerous and the proper length by continual grinding against the upper tusks that grow out sideways.

Wild Boar Food and Eating Behavior

Wild boars are omnivores — animals that eat a variety of things, including plants and animals — and like to root and forage on the forest floor or ground for roots, tubers, bulbs, acorns, spiders, snails, centipedes, moles, shrews, birds, eggs, crayfish, shoots, tree bark, leaves, grubs, insects, worms, crabs, fallen nuts, reptiles, carrion, and even frogs and poisonous snakes. . In the United States, wild boars are immune to snakebites and eat snakes. In some places they have been brought in get rid of snakes and have achieved that goal.

wild boar anatomy

Pigs were originally forest creatures that fed on acorns. Wild boars use their snouts and whetters to located and dig up food. They actively forage throughout the year mainly at night and seek out eat grass, roots, weeds, nuts, bulbs, windflowers, and cultivated crops. They are particularly fond of tender shoots of grass and mast (nuts) such as acorns, beechnuts and pecans. Population size is often determined by the availability of mast. Wild boars in Europe eat almost anything that can be found in the forested environment: acorns, beechmast, chestnuts, snails, frogs, mice, lizards and carrion. They are particularly fond of an underground fungus that grows on the roots on trees more than a foot below the ground— truffles.

Wild boars predominantly eat plant matter but occasionally eat bird eggs, carrion, small rodents, insects, and worms. Wild boars have reportedly preyed on small calves, lambs, and other livestock when the opportunity presents itself. They adjust their diets based on what is available, which can vary with seasons, weather conditions, and locations. They tend to do most of their foraging in the late evening and into the night.[Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

Wild Boar Behavior

Wild boars are terricolous (live on the ground), nocturnal (active at night), crepuscular (active at dawn and dusk), motile (move around as opposed to being stationary) and social (associates with others of its species; forms social groups). The size of their range territory is 1.1 to 3.9 square kilometers (0.4 to 1.5 square miles) and depends on several factors sich as number of individuals in the group, food resource availability, geographic range, and predation threats. Females tend to occupy smaller ranges and keep to covered areas within a home range to protect themselves and their young. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

Female wild boars are social animals that tend to live in groups. These groups are called sounders and are generally made up of several females and their offspring. They move their home range as needed, according to resource availability and weather. Males tend to be more solitary after reaching maturity and join with groups during mating.

Large boars are generally solidarity animals except in the mating season. Young females and males sometimes roam in groups called drifts. Males leave the drift when are about a year old. Groups of females accept some overlap between their herd and others, but young adults remain distinct groups. Males generally occupy larger areas per animal than females. They often tolerate overlap of ranges with other males except during the mating season when they become more territorial prepare to compete for breeding rights.

Wild boars forage primarily at night. During the day they spend most of their time hiding in dense thickets. Wild boars like to wallow in mud to keep cool and suffocate parasites. They also rub themselves with scent and greet each other by sniffing each other's nose. Wild boars don't need to migrate or hibernate like other animals. They can survive the winter by eating roots that other animals can't eat.

In some habitat, wild boars may be active both day and night. In warmer weather, they tend to stay fairly inactive during the day. In cooler weather, they may feed during the day, with foraging activities usually increasing in the late evening. During the evening and night, wild boars emerge in open areas to search for food. If boars actively feed during the day, they tend to avoid open areas where they are are more vulnerable to predation.

Wild Boar Locomotion, Senses and Communication

Boars tend to move along at a slow and steady pace but when disturbed are capable of running at very fast speeds. Their short legs are ideal for getting around in forests and brush but they are not very useful for getting around in deep snow. Japanese wild boars can reach running speeds of 40 km/h from a standing start and can jump over one meter in height. Even piglets are very quick. The presence of wild boars can be ascertained by the presence of their distinctive four-toe hoofprints and ruts and holes made by digging up tubers and roots. In marshy areas you can see the disturbed areas where they waddle in the mud. Wild boars are good swimmers. They often snort when they swim.

Wild boars sense using touch, sound and chemicals detected by smelling. They have strong senses of smell and hearing but not very good eyesight. They can often smell danger but, especially in high grass, they can't see where it is. Their long, flattened snouts allow for a heightened sense of smell but when forage for food, they tend to keep their snout near the ground, impeding their ability to smell and sense danger. Their eyes are located on the sides of their head, giving them good peripheral vision. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

baby wild pigs

Wild boars communicate with sound and chemicals usually detected by smelling. They communicate vocally, using growls to indicate aggressive behavior and squeals to show excitement and approachability They use chemicals to interact with each other. By rubbing on the ground, they can leave chemical traces behind. Studies of domesticated pig have show that sows, using their excellent sense of smell, can to distinguish their own piglets among piglets of other litters just 24 hours after birth. |=|

Wild Boar Reproduction

Like their domestic cousins, wild boars have a high reproductive rate and can multiple very quickly. Sows can reach sexual maturity at 10 months and can produce two litters a year. Wild boar have more offspring than many other animals. Litters often have more than eight piglets and are produced after a four month gestation period. In contrast cows become sexually mature after two years and generally only bear one calf after a nine month gestation period. According to the Guinness Book of Records, the world's largest pig litter contained 37 piglets.

Wild boars engage in year-round breeding. They may breed once or twice in a year. The gestation period ranges from 108 to 120 days, with the average being 115.2 days. The average number of offspring is five to seven. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

Wild boars often can be found in large groups called sounders that are made up of six to 20 closely-related females with their young, but may contain over 100 individuals. Mating is often dependent on food availability. If females can’t get enough nutritio and food they may hold off on breeding. Males can become sexually mature as early as five months.

Wild Boar Mating and Fighting

Wild boars are polygynous (males have more than one female as a mate at one time).Males have more testosterone in their bloodstream during the winter months. During short days they have higher concentrations of sex hormones in their semen plasma than on shorter days. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

Polygynous males are attracted to groups of females that are in estrus. They become very aggressive and compete for the opportunity to breed with a sounder. Successful males chase females in estrus, nudging them to show their interest. If the female is also interested, she may respond by urinating. If the female does not urinate, the male may give up after several minutes. |=|

Estrus cycles generally last 21 to 23 days and females are generally only fertile for four days. Males follow estrous females until finally the female gives in and let a male mount her. Mating takes about eight minutes. Males release a tremendous amount of sperm for their size. Large amount of sperm fills the female so there is no room for sperm for rivals. The male then follows the female around to make sure she doesn't mate with another wild boar.

Males are most aggressive during the mating season. They usually don't fight because the can inflict serious injuries with their tusks. Instead they usually show off their tusks by swinging their heads from side to side and laying territorial scent markers. Males with the biggest tusks and warts are usually dominate

"When a boar fights," Bill Brett told Smithsonian, "he opens his mouth and throws his head sideways and up, and then jerks it back. Lots of times this leaves two cuts, one from the tush and one from the whetter. He's at his peak as a fighter from about two year sold., when his tuskes are an inch and a half long, to about 6 years old, when he begins to loose a little of his quickness, and his tusks start getting long enough to curl back some and not hit straight in."

Wild Boar Offspring

Wild boar piglets are precocial. This means they are relatively well-developed when born. Parental care — both provisioning and protecting — is provided by females. Males are not involved in the raising of offspring. The post-independence period is characterized by the association of offspring with their mothers. The age in which young are weaned ranges from eight to 12 weeks. On average females reach sexual or reproductive maturity at 10 months and males do so at five to seven months. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

After mating, females remain with their group for the four month gestation period and then retire to give birth alone in a cave, a den of another animal, an abandoned building or leaf-lined holes in the ground. Mother wild boars are always hungry as they divide time between eating and taking take care of their young.

Newborn piglets weigh 0.4 to 0.8 kilograms. weeks. At birth, young boars generally have yellowish-brown stripes running down their backs that disappear into an even coloration within about four months. The striped patterning is probably not totally camouflage because when a predator approaches they get up and run (camouflage is most effective if an animal remains still). Perhaps the patterning is a signal to parents not to eat their babes.

At birth, piglets have very little body fat and few energy stores. Their mortality rates are relatively high. According to Animal Diversity Web: By producing more young, female boars increase the chances that some offspring will survive. Sows with large litters have been known to accidentally crush their progeny. However, research suggests that this may be purposeful, to increase the odds of survival for the rest of the litter. Reduced competition among siblings for feeding is a result of smaller litter sizes. Weaker piglets may try to feed several times, before being beaten out by their siblings, and simply dying from malnourishment.

Females leave their sounder to give birth and return with their young after giving birth to their litter. Females in a sounder tend to give birth around the same time and help take care of offspring that are not their own and may even nurse them. However, more often sows reject piglets that are not their own. Females work collectively to protect all offspring within their sounder. When traveling, mothers keep their young in the middle, with adults in the lead and rear. Young are often left with one female as protection, while the rest of the group forages for food. Through play young piglets learn self protection.

Even after reaching maturity, female piglets tend to stay in the same groups in which their mothers reside. These herds tend to have some overlap, and it is not uncommon for herds to split into subpopulations. Males stay with their mothers until they are one to two years old and then leave the herd. After departing, they generally only join a sounder during mating season.

Wild Boars as Prey

Wild boars have few natural predators other than bears, wolves, cougars, leopards, tigers and man but since bears and wolves are not so numerous and have a hard time attacking wild boars anyway, humans present the only real threat. Piglets are preyed on by eagles, hawks, lynx and foxes. Sometimes they are snatched from burrow while their mother is away. Sometimes they drown or catch hypothermia in flooded burrows.

Wild boars are fierce fighters. They usually avoid trouble but they can be dangerous if cornered. With their sharp ivory tusks wild boars can easily defend themselves against bears and wolves. They strike hard and quick and can inflict lethal blows with their tusks.

Adults use their coloration to help them blend in with their surroundings. Piglets have stripes running the length of their back, enabling them to remain concealed within undergrowth and in their nest. By traveling in groups, females are able to collectively protect their young from predation while on the move. When traveling, sows lead and form the rear of groups while the piglets are kept in the middle for protection. [Source: Kristin Wickline, Animal Diversity Web (ADW) |=|]

Some wild pig species: 10 Philippine Warty Pig (Sus philippensis) Mindoro Warty Pig (Sus oliven) 12 Palawan Bearded Pig (Sus ihoanobirbus) 13 Bearded Psg (Sus barbatus), 14 Sulawesi Warty Pig (Sus celebensis) 15 Javan Warty Pig (Sus venucosus) 16 Eurasian Wild Pig (Sus scrola) 17 Pygmy Hog (Porciila salvimi)

Image Sources: Wikimedia Commons

Text Sources: Animal Diversity Web animaldiversity.org ; National Geographic, Live Science, Natural History magazine, David Attenborough books, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Discover magazine, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Wikipedia, The Guardian, Top Secret Animal Attack Files website and various books and other publications.

Last updated May 2025