Information and advice about managing feral pigs (Sus scrofa).
General
Feral pigs occupy about 92,000 hectares in New Zealand. Densities have reached over 100 animals per square kilometre in the past, and still reach about 40 per square kilometre in areas with good food supply and little hunting. The illegal release of feral pigs by hunters is thought to contribute to new populations continuing to establish. Pigs cannot easily digest cellulose and so require a broad diet that includes succulent vegetation, fruit, seeds, fungi and animals. One limit to the distribution and density of pigs is their requirement for protein, particularly for sows rearing piglets. Their omnivorous diet and their ability to increase numbers very rapidly contribute to their potential problem.
Adverse effects of feral pigs
Feral pigs may affect the viability of threatened species and affect native ecosystems and biodiversity directly by eating plants and animals. Indirect threats arise from soil disturbance while rooting for food or by competing for food with native animals. In some favoured sites pigs can root up most of the ground surface. While this may encourage the regeneration of beech species particularly, constant disturbance negates this. Predation on lambs and damage to pasture, while once a significant effect, is now isolated and largely dealt with by landowners.
Control
Recreational hunting provides some control on feral pig numbers. Feral pigs can be stalked and shot with a rifle, but are more often hunted with specially trained dogs. More information on the ecology, history and management of pigs in New Zealand can be located at Global Invasive Species database.
Environment Canterbury's role
Environment Canterbury can facilitate and assist community and land occupier selfhelp programmes to destroy possums, mustelids, feral cats, feral deer, feral goats, feral pigs and wasps particularly adjacent to areas of high environmental value to complement control operations or in other areas if there is community support for control operations; For example, the Banks Peninsula possum programme.