Mortality Threats to Birds - Feral Pig (Sus scrofa) |
Pigs have been introduced by man to many parts of the world. They cause serious problems wherever they are introduced, including Florida, Tennessee, Texas, California and Hawaii, with the potential to convert healthy landscapes into barren moonscapes. In Hawaii, feral pigs have been described as “death” to the native rainforest. They uproot native vegetation which allows non-native plants to invade. In addition, depressions are created in the soil from the uprooted vegetation which collect rainwater and create ideal breeding habitat for introduced mosquitos that spread lethal, non-native diseases such as avian malaria and avian pox to endangered birds. Feral pigs also help in the spread of non-native weeds by ingestion of the fruit with the seeds passing into their droppings. Feral pigs also transmit many diseases. They can live in a wide range of habitats including agricultural areas, coastal areas, natural and planted forests, grasslands, and wetlands.
Polynesians originally introduced the small Polynesian pig (20 kilos) ca. 400 A.D. to the Hawaiian Islands. However, the Polynesian pig has been completely replaced by the larger and more aggressive (200 kilo) European domesticated breeds which were first introduced to the Hawaiian Islands by Captain James Cook in 1778.
Pigs are very effective predators of ground
nesting seabirds such as albatrosses, boobies, Hawaiian
Petrel, and Newell’s
Shearwater. Hawaiian forest birds such as Alala,
various species of honeycreepers; Maui
Parrotbill are impacted by the destruction of native rainforest.
Pigs are very mobile animals and
their home ranges are not fixed. Under stress they may disperse
considerable distances, which can make it uneconomic for an
individual landowner or agency to control a pig population.
Standard methods of control are hunting with trained dogs,
setting snares and traps, and even hunting by helicopter in
remote sensitive areas. Fencing is also used to keep pigs
out of sensitive areas. There is a hunting season in Hawaii,
but also a bag limit. The biggest impediment to control and
eradication of feral pigs from the Hawaiian Islands is political.