The wild boar (Sus scrofa), 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.
As of 2005, 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 (both male and female). 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.
Boars are typically social animals, living in female-dominated sounders consisting of barren sows and mothers with young led by an old matriarch. Male boars leave their sounder at the age of 8–15 months, while females either remain with their mothers or establish new territories nearby. Subadult males may live in loosely knit groups, while adult and elderly males tend to be solitary outside the breeding season.
The breeding period in most areas lasts from November to January, though most mating only lasts a month and a half. Prior to mating, the males develop their subcutaneous armour in preparation for confronting rivals. The testicles double in size and the glands secrete a foamy yellowish liquid. Once ready to reproduce, males travel long distances in search of a sounder of sows, eating little on the way.
Once a sounder has been located, the male drives off all young animals and persistently chases the sows. At this point, the male fiercely fights potential rivals. A single male can mate with 5–10 sows. By the end of the rut, males are often badly mauled and have lost 20% of their body weight,[4] with bite-induced injuries to the penis being common. The gestation period varies according to the age of the expecting mother. For first-time breeders, it lasts 114–130 days, while it lasts 133–140 days in older sows. Farrowing occurs between March and May, with litter sizes depending on the age and nutrition of the mother. The average litter consists of 4–6 piglets, with the maximum being 10–12. The piglets are whelped in a nest constructed from twigs, grasses and leaves. Should the mother die prematurely, the piglets are adopted by the other sows in the sounder.
