Many feral animals can sometimes be captured at little cost and are therefore an important economic resource. Throughout most of Polynesia and Melanesia feral pigs are the main sources of animal protein. Prior to the Free-roaming Wild Horse and Burro Protection Act of 1971, American mustangs were often captured and sold for horsemeat. In Australia feral goat, pig and camel meat is exported. At certain times, animals were sometimes deliberately left to go feral, typically on islands, in order to be later recovered for profit or food use for travelers (particularly sailors) at the end of a few years.