Wild Boar - Feral Pigs

Feral Pigs

Domestic pigs can escape and quite readily become feral, and feral populations are problematic in several ways. They can cause small amounts of damage to trees and other vegetation and may feed on the eggs of ground-nesting birds and turtles. Feral pigs often interbreed with wild boar, producing descendants similar in appearance to wild boar; these can then be difficult to distinguish from natural or introduced true wild boar. The characterisation of populations as feral pig, escaped domestic pig or wild boar is usually decided by where the animals are encountered and what is known of their history. In New Zealand, for example, feral pigs are known as "Captain Cookers" from their supposed descent from liberations and gifts to Māori by explorer Captain James Cook in the 1770s. New Zealand feral pigs are also frequently known as "tuskers", due to their appearance.

One characteristic by which domestic and feral animals are differentiated is their coats. Feral animals almost always have thick, bristly coats ranging in colour from brown through grey to black. A prominent ridge of hair matching the spine is also common, giving rise to the name razorback in the southern United States, where they are common. The tail is usually long and straight. Feral animals tend also to have longer legs than domestic breeds and a longer and narrower head and snout.

A very large swine dubbed Hogzilla was shot in Georgia, United States, in June 2004. Initially thought to be a hoax, the story became something of an internet sensation. National Geographic Explorer investigated the story, sending scientists into the field. After exhuming the animal and performing DNA testing, it was determined that Hogzilla was a hybrid of wild boar and domestic swine. As of 2008, the estimated population of 4 million feral pigs caused an estimated US$800 million of property damage per year in the U.S. The problematic nature of feral hogs has caused several states in the U.S. to declare feral hogs to be an invasive species. Often, these states will have greatly reduced (or even non-existent) hunting regulations regarding feral hogs. In Missouri, no hunting permit is required for the taking of wild boar; hunters may take as many as they like with any weapon. The Missouri Department of Conservation requests that hunters who encounter feral hogs shoot them on sight. Caution is advised, as feral pigs can use their tusks defensively, and hog hunters consider them dangerous when injured or cornered.

At the beginning of the 20th century, wild boar were introduced for hunting in the United States, where they interbred in parts with free roaming domestic pigs. In South America, New Guinea, New Zealand, Australia and other islands, wild boar have also been introduced by humans and have partially interbred with domestic pigs.

In South America, also during the early 20th century, free-ranging boars were introduced in Uruguay for hunting purposes and eventually crossed the border into Brazil sometime during the 1990s, quickly becoming an invasive species, licensed private hunting of both feral boars and hybrids (javaporcos) being allowed from August 2005 on in the Southern Brazilian state of Rio Grande do Sul, although their presence as a pest had been already noticed by the press as early as 1994. Releases and escapes from unlicensed farms (established because of increased demand for boar meat as an alternative to pork), however, continued to bolster feral populations and by mid-2008 licensed hunts had to be expanded to the states of Santa Catarina and São Paulo. Such licensed hunts were, however, forbidden in 2010 by IBAMA, which argued the necessity of additional studies for devising a strategy of pest control for boars. Meanwhile, boars and boar crosses were spotted in the State of Rio de Janeiro, where cases of crop raiding were reported in the municipality of Porciuncula. There was also the danger of an escape from an unlicensed farm in Nova Friburgo, which was closed in December 2011, all 316 animals being sent to an abattoir. In October 2010, a rural worker was killed by a boar in Ibiá, in the State of Minas Gerais.

Recently established Brazilian boar populations are not to be confused with long established populations of feral domestic pigs (porcos monteiros), which have existed mainly in the Pantanal for more than a hundred years, along with native peccaries. The demographic dynamics of the interaction between feral pigs populations and those of the two native species of peccaries (Collared Peccary and White-lipped Peccary) is obscure and is being studied presently. It has been proposed that the existence of feral pigs could somewhat ease jaguar predation on peccary populations, as jaguars would show a preference for hunting pigs, when these are available.

Feral hogs can rapidly increase their population. Sows can have up to 10 offspring per litter, and are able to have two litters per year. Each piglet reaches sexual maturity at 6 months of age. They have virtually no natural predators.