Auckland Island pig

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The Auckland Island Pig is a feral breed of domestic pig (Sus scrofa) found on subantarctic Auckland Island, New Zealand. It has inhabited the island since 1807,[1] and, as an invasive species, has had a considerable environmental impact.

History[edit]

In the 18th and 19th centuries, Europeans released domestic pigs on many subantarctic islands.[2] Various introductions of pigs were made to uninhabited Auckland as a source of food for stranded sailors or visiting whalers; the first took place in 1807, with further liberations in 1840, 1842 and the 1890s. By the end of the 19th century, the island held a thriving population of pigs of mixed origin which was largely undisturbed until the late 20th century, producing a distinctive breed.[3]

Description[edit]

The physical appearance and size of the pigs on Auckland Island is similar to the feral pigs located on the main island of New Zealand.[4] They have coats of thick hair which are black, or white or brown with black markings.[4] They also have long, narrow heads and snouts, straight tails, are relatively small and very athletic.[3] The average weight of an adult boar is 41.7 kg, and an adult sow 37.3 kg.[4]

Genetics[edit]

The pigs that were released onto Auckland Island are derived from domestic breeds of European and Asian pig lineages that are now rare or extinct.[5] Population genetic variation is low within the Auckland Island pig population compared to other breeds of pigs such as European and Asian.[2] These relatively pathogen free pigs have been used to derive a biocertified herd as a source of cells for xenotransplantation[1].

Behaviour and ecology[edit]

Distribution and habitat[edit]

As of the late 20th century the substantial pig population occupied the whole of the island, with equal numbers of males and females.[4] During the summer months, the pigs inhabit both the coastal forest and high open country of the island, while during the winter months, a majority of the pig population will reside in the coastal forest and not the open country.[4] The pigs' diet is simple, consisting mostly of plant food. In the high country they eat a variety of different plants and earth worms. Those that inhabit the coast also eat a wide variety of plants, but their diet also includes bark, invertebrates, the remains of dead birds and sea lions, and the regurgitations of sea lions.[4]

Effects on vegetation and wildlife[edit]

The pigs have destroyed much of the islands' flora, though remnant plant communities of Pleurophyllum, Stilbocarpa and Anisotome are relatively safe because they are only accessible on cliffs where the pigs cannot go.[4] Since the depletion of many plant food resources, the pig population on Auckland Island has remained relatively low.[4] The feral pigs have also had negative effects on other wildlife throughout the island. They have dug up burrows of birds to steal their eggs such as petrels, albatrosses, mollymawks, penguins and shags.[4]

Management[edit]

A decision was made by New Zealand's Department of Conservation that species introduced to the Auckland Islands should be eradicated in the course of a program to restore the natural ecosystems. Consequently the Rare Breeds Conservation Society of New Zealand (RBCSNZ) decided to attempt to preserve the breed in captivity. In 1999 a RBCSNZ expedition caught and removed seventeen pigs, including several pregnant sows, from Auckland Island, transferring them to Invercargill, New Zealand. These animals have since bred successfully and the breed is not at risk.[3]

References[edit]

  1. ^ Robins, Judith H; Elizabeth Matisoo‐Smith, Howard A. Ross (June 2003). "The Origins of the Feral Pigs on the Auckland Islands". Journal of the Royal Society of New Zealand 33 (2): 561–569. doi:10.1080/03014223.2003.9517744. 
  2. ^ a b Fan, Bin; Jaime Gongora, Yizhou Chen, Olga Garkavenko, Kui Li, Chris Moran (June 2005). "Population Genetic Variability and Origin of Auckland Island Feral Pigs". Journal of the Royal Society of New Zealand 35 (3): 279–285. doi:10.1080/03014223.2005.9517784. 
  3. ^ a b c RBCSNZ: Auckland Island Pigs accessed 7 January 2008
  4. ^ a b c d e f g h i Challies, C.N. (1975). "Feral Pigs (Sus scrofa) on Auckland Island: Status, and Effects on Vegetation and Nesting Sea Birds". New Zealand Journal of Zoology 2 (4): 479–490. doi:10.1080/03014223.1975.9517889. 
  5. ^ Gongora, Jamie; Peter Fleming, Peter B.S. Spencer, Richard Mason, Olga Garkavenko, Johann-Nikolaus Meyer, Cord Droegemueller,Jun Heon Lee, Chris Moran (November 2004). "Phylogenetic relationships of Australian and New Zealand". Molecular Phylogenetics and Evolution 33 (2): 339–348. doi:10.1016/j.ympev.2004.06.004.