T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Pig (Feral) Sus scrofa

Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Suidae
Genus: Sus
Species: S. scrofa
Binomial name: Sus scrofa
Common names: Captain Cookers, Wild pigs.

All feral pigs in New Zealand are the descendants of domestic pigs. They were first released in New Zealand in the 1770s by Captain James Cook as a food source. Captain Cook’s pigs were derived from the old English (Tamworth, Berkshire and the large blacks) and have subsequently formed the base of the country’s wild pig population.
In 1918 returned servicemen were settled on allotted farms after the First World War but difficult farming conditions, poor soil fertility and steep hill country, led to lots of these farmers walking off the land releasing their domestic pigs. A wild population soon established from the escaped and released domestic pigs. 
Feral pigs frequent native and exotic forests, scrubland, and marginal farmland with areas of cover. Feral pigs are omnivorous and are opportunistic feeders. They pose a serious threat to biodiversity by eating seedlings and root systems, native insects and ground-nesting birds and their young. For example by feeding on the remnant populations of indigenous land snails.
Feral pigs also contribute to erosion through rooting, trampling, compaction and wallowing. Pigs often form large and distinctive game trails through areas of regenerating vegetation. They are a nuisance to backcountry farmers because of their destructive feeding habits, often living in groups and overturning large areas of pasture in search of food. Pigs will kill newborn lambs and are a known vector of the disease Bovine Tb.
Feral pigs are distinctively shaped with large shoulders, small rear quarters and a straight hairy tail. Often black in colour, they are also grey, brown, ginger, white, or any combination of these colours. Adults can weigh anything between 40 to 180kg. Feral pigs are omnivorous, opportunistic feeders with a wide-ranging diet. They will eat grasses, roots, herbs, seeds, insects and small animals, and will scavenge decomposing carcasses.

In Northland, wild pigs may be spreading a disease that is killing kauri trees. A soil-borne fungal disease called phytophthora taxon agathis, which kills seedlings and trees of all ages, has killed thousands of kauri in the past 10 years. New research by University of Auckland researcher Dr Cheryl Krull has found wild pigs contribute to the spread of the disease, moving infected soil microbes throughout a forest.

Damage to a paddock by wild pigs.

The result of a day's wild pig hunting competition

Distribution map of the feral pig (Pink area)

Thanks to Wikipedia for text and information http://creativecommons.org/licenses/by-sa/3.0/