The feral goat is the domestic goat (Capra aegagrus hircus) when it has become established in the wild. Feral goats occur in Australia, New Zealand, Ireland, Great Britain, Hawaii, Brazil, Honduras, Lebanon, Panama, Madagascar, Comoro Islands, Mauritius, Réunion, New Guinea, the Galapagos, Cuba and in many other parts of the world.
When feral goats reach large populations in habitats which are not adapted to them, they may become an invasive species with serious negative effects, such as removing native scrub, trees and other vegetation. However, in other circumstances they may become a natural component of the habitat, even replacing locally extinct wild goats. Home range use and movement patterns of non-native feral goats in a tropical island montane dry landscape. Feral goats are sometimes used for conservation grazing, to control the spread of undesirable scrub or weeds in open natural habitats such as chalk grassland and heathland.
The Arapawa Island goat is a breed of feral goat found only on Arapaoa Island. Auckland Island goats were extirpated in the wild in the late 20th century. The New Zealand feral goat is the descendant of many breeds of goat, such as Angora, Kiko, Spanish, Pygora, Boer, Saanen, Nubian and Alpine.
Source: Wikipedia