A feral animal or plant is one that lives in the wild but is descended from domesticated individuals. As with an introduced species, the introduction of feral animals or plants to non-native regions may disrupt ecosystems and has, in some cases, contributed to extinction of indigenous species. The removal of feral species is a major focus of island restoration.

The water buffalo, also called the domestic water buffalo or Asian water buffalo, is a large bovid originating in the Indian subcontinent and Southeast Asia. Today, it is also found in Italy, the Balkans, Australia, North America, South America and some African countries. Two extant types of water buffalo are recognized, based on morphological and behavioural criteria: the river buffalo of the Indian subcontinent and further west to the Balkans, Egypt and Italy and the swamp buffalo, found from Assam in the west through Southeast Asia to the Yangtze Valley of China in the east.