|A domestic goat (Capra hircus).|
The goat was originally domesticated approximately ten thousand years ago in Iran, and feral goats of course came from the domestic strains. Introduction methods included purposeful release just in case a ship was wrecked and people became marooned. Also, some goats were introduced to islands for use as milk producers. They were considered favorable for these purposes because they are able to survive so well in harsh conditions, including eating virtually anything. This is part of the reason why goat meat and milk are consumed in higher quantities than any other animal's meat or milk. They are also heavily used for their fur and, of course, the angora goat is known for its very soft fur that can be made into mohair.
Unfortunately, of course, the species has become invasive. Goats introduced to islands have lead to drops in plant biodiversity, including threatening many vulnerable species. This, in turn, has caused erosion and loss of native animal species who feed on the plants the goats have affected. Control methods vary, but elimination is possible on fairly small islands. Hunting can be highly affective, including aerial hunting in the terrain is favorable. "Judas goats," which will seek out wild herds, are also used, as are hunting dogs specially trained to go after goats. Again, however, these methods become less helpful the large the area on which eradication must take place.