General Impact
Location Specific Impacts:Australia 
Habitat alteration: Fleay’s Barred-frog (Mixophyes fleayi) is listed as 'Endangered (EN)' in the IUCN Red List of Threatened Species. Endemic to Australia it occurs in wet forests from the Conondale Range in south-east Queensland, south to Yabbra Scrub in north-east New South Wales. While the specific reason for its decline is not known large areas of its habitat are being degraded and altered due to urban encroachment, forest logging, trampling and rooting by pigs (Sus scrofa) and domestic stock; and the invasion of alien invasive weeds like mistflower (Ageratina riparia) and crofton weed (Ageratina adenophora). The Chytrid fungus (Batrachochytrium dendrobatidis) has been identified as the cause of illness and death in some populations (Hines et al 2004).
Habitat alteration: The Southern Gastric Brooding Frog (Rheobatrachus silus) is listed as 'Extinct (EX)' in the IUCN Red List of Threatened Species. Endemic to Australia it occured in the Blackall and Conondale Ranges in south-east Queensland inhabiting streams and catchments of the Mary, Stanley and Mooloolah Rivers. It has not been recorded in the wild since 1981. The reasons for its decline are unknown; the Chytrid fungus (Batrachochytrium dendrobatidis) is suspected to have caused declines in populations. Its habitat is also degraded due to trampling and rooting by pigs (Sus scrofa) and the spread of the alien mistflower (Ageratina riparia) (Meyer et al 2004)
Habitat alteration: The Mount Glorious Day Frog (Taudactylus diurnus) is listed as 'Extinct (EX)' in the IUCN Red List of Threatened Species. An Australian endemic, it occurred in disjunctive populations in three sub-coastal mountain ranges (Blackall, Conondale, and D’Aguilar Ranges) in the south-east Queensland region from Coonoon Gibber Creek in the north to Mount Glorious in the south. It has not been recorded in the wild since 1979. The reasons for its decline are unknown; the Chytrid fungus (Batrachochytrium dendrobatidis) is suspected to have caused declines in populations. Its habitat is also degraded due to trampling and rooting by pigs (Sus scrofa) and the spread of the alien mistflower (Ageratina riparia); Lantana (Lantana camara) and the alien grass Baccharis halimifilia. Frog populations were absent where pigs had caused damage and where alien plants had invaded (Hero et al 2004). Nuku Hiva Is. (French Polynesia)
Threat to endangered species: Grazing by feral pigs pose a major threat to the survival of the monotypic 'Critically Endangered (CR)' palm Pelagodoxa henryana (Johnson 1998) French Polynesia 
Habitat alteration: The impact of pigs on the biodiversity of these islands has not been studied so far. The natural rain forests are being devastated by wild pigs on the tops of Hiva Oa and on high altitude plateaus from Temehani to Raiatea (Meyer, pers. comm., 2007).
Interaction with other invasive species: Pig's involvement in seed dispersal of invading alien plants has been observed for Syzygium cumini on the island of Hiva Oa, for Miconia calvescens and Psidium cattleianum on Raiatea, and for Chrysobalanus icaco on Raiatea and Fatu Hiva in the Marquesas (Meyer, 2004a, et pers. comm., 2007). Montserrat
Ecosystem change: Sus scrofa In medium-long term they are likely to have a very major impact on forest ecology, in particular through arresting tree succession (by eating seedlings) (Pers.comm., Hilton, 2004 in Varnham, 2006).
Habitat alteration: Sus scrofa uproot patches of Heliconia caribbea plants, the main nest plants for the 'Critically Endangered (CR)' endemic Montserrat oriole (see Icterus oberi in IUCN Red List of Threatened Species) and a valuable food source for nectarivorous birds and insects. Loss of this plant may also increase soil erosion and flooding downstream (Pers.comm., Hilton, 2004 in Varnham, 2006)
Reduction in native biodiversity: Sus scrofa are often reported as eating large numbers of terrestrial arthropods (though population impacts under-recorded).
Threat to endangered species: Sus scrofa are believed to trample and predate turtle nests (Martin, 2003 in Varnham, 2006). Marine turtles that nest in Montserrat include the 'Critically Endangered (CR)' Hawksbill turtles (see Eretmochelys
imbricata in IUCN Red List of Threatened Species); the 'Endangered (EN)' green turtle (see Chelonia
mydas in IUCN Red List of Threatened Species); the 'Endangered (EN)' loggerhead turtle (see Caretta
caretta in IUCN Red List of Threatened Species) and the 'Critically Endangered (CR)' leatherback turtle (see Dermochelys
coriacea in IUCN Red List of Threatened Species).
S.
Scrofa are thought likely to predate slower moving herpetofauna, such as 'mountain chicken' the near-endemic 'Critically Endangered (CR)' (see Leptodactylus
fallax in IUCN Red List of Threatened Species), and perhaps, if they enter its range, the endemic Montserrat galliwasp (see Diploglossus
montisserrati in IUCN Red List of Threatened Species) (Pers.comm., Hilton, 2004 in Varnham, 2006).
S. scrofa are likely to directly destroy mountain chicken nests by their extensive digging and wallowing along watercourses (Pers.comm., Hilton, 2004 in Varnham, 2006). New Caledonia (Nouvelle Calédonie)
Competition: Warner (1948) mentions several introduced species as predators of a native bird called the kagu (Rhynochetos jubatus see in IUCN Red List of Threatened Species). “Escaped pigs and the introduced rats are … causing heavy damage to the kagu at the present time. They not only kill the birds but also destroy its food supply of land snails and large earthworms…. I often found snail shells in rat runways and burrow entrances and scattered about in other odd places. Many of these had been gnawed in typical rat fashion.… The pig and rat may also take young birds and eggs …"
Predation: Warner (1948) mentions several introduced species as predators of a native bird called the kagu ("http://www.iucnredlist.org/details/143794/0">Rhynochetos jubatus see in IUCN Red List of Threatened Species). “Escaped pigs and the introduced rats are … causing heavy damage to the kagu at the present time. They not only kill the birds but also destroy its food supply of land snails and large earthworms…. I often found snail shells in rat runways and burrow entrances and scattered about in other odd places. Many of these had been gnawed in typical rat fashion.… The pig and rat may also take young birds and eggs …" Grand Terre Is. (New Caledonia) (New Caledonia (Nouvelle Calédonie))
Reduction in native biodiversity: The negative impacts of pigs on malacofauna is proven, especially on the Placostylus genus known locally as "les bulimes" (Brescia, 2005) and is strongly suspected on terrestrial microfauna, some ground nesting birds as well as on the fruit, seeds and tubers of many plants (Pascal et al., 2006). Hawaiian Islands (United States (USA))
Physical disturbance: “Watersheds, forests, and range are damaged when pigs root excessively ….” On Hawai‘i, with the control of feral goats and the elimination of feral sheep from certain habitats, the feral pig “has emerged as the most prominent agent of ecological perturbation, of wet forests in particular”.
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