Most foxes live 2 to 3 years, but they can survive for up to 10 years or even longer in captivity. Foxes are generally smaller than other members of the family Canidae such as wolves, jackals, and domestic dogs. Dogs (male foxes) weigh on average, 5.9kg and vixens (female foxes) weigh less, at 5.2kg (13 lbs and 11.5 lbs, respectively). Fox-like features typically include an acute muzzle (a "fox face") and bushy tail. Other physical characteristics vary according to their habitat. For example, the fennec fox (and other species of foxes adapted to life in the desert, such as the kit fox) has large ears and short fur, whereas the Arctic fox has small ears and thick, insulating fur.
Unlike many canids, foxes are usually not pack animals. Typically, they are solitary, opportunistic feeders that hunt live prey (especially rodents). Using a pouncing technique practiced from an early age, they are usually able to kill their prey quickly. Foxes also gather a wide variety of other foods ranging from grasshoppers to fruit and berries.
Foxes are normally extremely wary of humans and are not kept as pets (with the exception of the fennec); however, the silver fox was successfully domesticated in Russia after a 45 year selective breeding program. This selective breeding also resulted in physical and behavioural traits appearing that are frequently seen in domestic cats, dogs, and other animals: pigmentation changes, floppy ears, and curly tails.
Canids commonly known as foxes include members of the following genera:
Foxes are readily found in cities and cultivated areas and (depending upon species) seem to adapt reasonably well to human presence.
Red foxes have been introduced into Australia for hunting rabbits and to other countries for the same reason. Australia lacks similar carnivores, and the introduced foxes prey on native wildlife, some to the point of extinction. A similar introduction occurred in the seventeenth and eighteenth centuries in temperate North America, where European reds (Vulpes vulpes) were brought to the colonies for fox hunting, where they decimated the American red fox population through more aggressive hunting and breeding. Interbreeding with American reds, traits of the European red eventually pervaded the gene pool, leaving European and American foxes now virtually identical.
Other fox species do not reproduce as readily as the red fox, and are endangered in their native environments. Key among these are the crab-eating fox (Cerdocyon thous) and the African bat-eared fox. Other foxes such as fennec foxes, are not endangered, but will be if humans encroach further into their habitat.
Foxes have been successfully employed to control pests on fruit farms, where they leave the fruit intact.
Historians believe foxes were imported into non-native environments long before the colonial era. The first example of the introduction of the fox into a new habitat by humans seems to be Neolithic Cyprus. Stone carvings representing foxes have been found in the early settlement of Göbekli Tepe in eastern Turkey.