Definitions

Next to the meaning of the word feral described here, from Latin fera, "a wild beast", the word has a second unrelated meaning, from Latin feralis, "belonging to the dead", "funeral".

Animals

Plants

Domesticated plants that revert to wild are usually referred to as escaped, introduced, or naturalized. However, the adaptive and ecological variables seen in plants that go wild closely resemble those of animals.

Susceptibility

Certain familiar animals go feral easily and successfully, while others are much less inclined to wander and usually fail promptly outside domestication.

Degree

Some species will detach readily from humans and pursue their own devices, but do not stray far or spread readily. Others depart and are gone, seeking out new territory or range to exploit and displaying active invasiveness.

Persistence

Whether they leave readily and venture far, the ultimate criterion for success is longevity. Persistence depends on their ability to establish themselves and reproduce reliably in the new environment.

Tenure of domestication

Neither the duration nor the intensity with which a species has been domesticated offers a useful correlation with its feral potential.

Examples of feral animals

The dromedary camel, which has been domesticated for well over 3,000 years, will also readily go feral. A substantial population of feral dromedaries, descended from pack animals that escaped in the 19th and early 20th centuries, thrives in the Australian interior today.

The cat returns readily to a feral state if it has not been socialized properly in its young life. (See Feral cats.) These cats, especially if left to proliferate, are frequently considered to be pests in both rural and urban areas, and may be blamed for devastating the bird, reptile and mammal populations. A local population of feral cats living in an urban area and using a common food source is sometimes called a feral cat colony. As feral cats multiply quickly, it is difficult to control their populations. Animal shelters attempt to adopt out feral cats, especially kittens, but often are overwhelmed with sheer numbers and euthanasia is used. In rural areas, excessive numbers of feral cats are often shot. More recently, the "Trap-Neuter-Return" method has been used in many locations as an alternate means of managing the feral cat population.

Sheep are close contemporaries and cohorts of goats in the history of domestication, but the domestic sheep is quite vulnerable to predation and injury, and thus rarely if ever is seen in a feral state. However, in places where there are little other predators, they get on well, for example in the case of the Soay sheep.