Wild boar

The wild boar is a shy animal that avoids contact with humans. They are omnivorous, mainly eating roots, plants, acorns and potatoes, but also consuming snails, earthworms and insect larvae. Wild boars are most active at dawn and dusk, and are rarely seen during the daytime. They thrive in forests, especially near farmland. They use their snouts to root around in the soil for food.

The first wild boars came to Sweden after the last ice age 8,000 to 10,000 years ago, around the same time as humans, but only became common once large forests had grown. By the 18th century, the wild boar was virtually extinct in Sweden. It was not until the 1940s that they were reintroduced, this time into enclosures. In the late 1990s a number of animals escaped, and it is from these that today’s wild boar population is descended. In the early 1980s, there were fewer than a hundred free-ranging wild boars in Sweden. A decade later, the population had grown to around 500. There are now around 300,000 wild boars in the wild.

Can weigh up to 200 kg

The wild boar gives a front-heavy impression, with an upright shoulder and a sloping back line, ending in a short, straight tail. The body is flattened from the sides, giving rather a narrow impression from the front or rear. The head is triangular in profile and the ears stand upright. The nose ends in a snout. Both sexes have canine teeth that protrude from the lower jaw.

A fully grown wild boar in Sweden is about 1 metre tall at the withers and just over 1.5 metres long. The sow (female) weighs 90 to 120 kilograms, while the boar (male) is heavier and can weigh up to 200 kilograms.

Striped piglets

The winter coat is dark greyish-brown to black, with a woolly, insulating undercoat. The summer coat is thinner and more short-haired. Piglets’ fur is long-striped in yellow and darker patches until they are a few months old, when they start to become increasingly solid coloured. The male has strong canine teeth in his lower jaw that are shaped like tusks. These tusks grow throughout the animal’s life, and are sharpened against the shorter, curved canines of the upper jaw. The droppings look like stacked-up flattened balls.

Wild boars are social animals, and for much of the year they form groups of sows with piglets. They are not territorial, but if a wild boar feels threatened it may defend itself forcefully.

Highly developed sense of smell and good hearing

The wild boar has a very highly developed sense of smell and good hearing, but its eyesight is weaker. Some observations suggest that they can smell a human from more than 500 metres away. Scent is probably also important in social interaction. Male boars mark their territory with both saliva and urine, and wild boars are often seen sniffing each other when they meet.

Many different calls

A common call is the short, deep grunt that is typical of the herd when they are rooting around or grazing. It is used to stay in contact with the others. It is normally heard as a series of questions and answers: “I’m here, where are you?” A grunt is quickly followed by a reply from another boar, and so on. Another sound is the warning call. It means “Watch out!”, and the reaction depends on the circumstances.

Other common sounds include a defensive squeal, which is used when a boar is threatened or attacked by a superior individual, and the male boar’s intense, staccato sequence of grunts used during courtship. Grunts also play an important role during suckling.

Omnivores with a varied diet throughout the year

Wild boars are omnivores, but most of their diet consists of plants. Roots make up most of their food intake during the winter. During the summer, wild boar will eat green sedges and thistle leaves, fallen fruit, beechnuts, acorns and hazelnuts.

From July until the autumn, they eat a lot of seeds and fruits, and then move on to cultivated crops. Their diet is dominated by seeds from cereals such as winter wheat and oats, oilseeds such as rape, and grass and potatoes. Boars rarely damage more than a few percent of a cultivated area, but where they do strike the damage can be devastating. Much of the damage is caused not by actual eating, but by rooting around in the ground and trampling grain.

They also eat earthworms and insect larvae, small rodents, young birds and eggs. Wild boar can also eat carrion that they find in the wild. An adult wild boar consumes about four kilograms of food each day in the summer. A piglet can survive on about half that, but needs more during the winter. If there is plenty of access to food, wild boars sometimes eat until they have difficulty moving and they then lie down to digest their food.

Circadian rhythm

In Sweden, wild boars are active for six to eight hours a day, mostly at night. In areas on the Continent where food is scarce, wild boars can be active around the clock.

Reproduction – most births in the spring
Both sows and boars reach sexual maturity during their first year of life, and normally mate the following year. All sows in a group are usually in heat at the same time, and most mating takes place between August and December. The sow is pregnant for about 115 days, which means that they usually give birth from February to May. However, due to the long mating season, piglets can be born at any time of the year. When the time comes to give birth, the pregnant sow digs a shallow pit in a suitable location. She lines the nest with vegetation that forms a protective covering for her newborn piglets.

Each piglet has its own teat

A sow can suckle up to eight piglets. Each piglet has its own teat that it always suckles on. An orphaned piglet may be suckled by a sow related to the mother, but only after the sow’s own piglets are satisfied.

The group rests in temporary dens in sheltered locations. The sow protects the piglets, suckles them, and keeps the group together with grunts. The piglets spend most of their time suckling for the first two weeks, and are not fully weaned until three or four months of age. Yearlings are dependent on their mother’s milk and guidance, and cannot survive the winter alone. When they are about a year old, it is time for the sow to have new babies and they are then pushed aside.

Rejected male boars can form their own groups

Young male boars that have been pushed aside sometimes form small groups from the same litter. They have already established the ranking order as piglets. The group is short-lived, and disbands when the boars reach about two years of age. Male boars older than two years live alone, except during the mating season. When the mating season occurs in autumn and winter, they join the roaming groups of wild boars.