Foxes are adapted to a wide range of climates and habitats, from Arctic to equatorial regions, seacoasts to mountains, and open woodlands to deserts. They will eat almost any small animal they can catch, including birds, fish, and insects, and will also eat carrion (dead flesh) left by other predators, birds' eggs, and fruit, grain, and other forms of vegetable matter. Most foxes hunt and forage at night and sleep during the day. Some foxes store food when it is plentiful for use when it is scarce.

Foxes dig burrows or enlarge the burrows of such other animals as badgers, wood-chucks, and prairie dogs. Some adult foxes sleep in their burrows, but adults of other species rest in rock crevices, hollow logs, or underbrush and use the burrows only as dens for their young. In the Arctic, foxes often dig holes in deep snow for shelter during blizzards.

Foxes of some species mate for life. Female foxes give birth once a year. Litter size generally ranges from 2 to 7. Both parents help in rearing the young. After the young are about five months old, they are able to fend for themselves. The parents then usually hunt alone until the next breeding season. With few exceptions, foxes do not hunt or travel in large packs.

Foxes look like small, slim dogs. They have bushy tails, large ears, and pointed snouts. The fox doesn’t need a wolf’s large, heavy jaw. Its prey is much smaller than a wolf’s prey.

Foxes hunt alone and at night. They have keen hearing and an excellent sense of smell. A fox can locate a mouse to eat just by listening to its squeaks in the grass.

Foxes live and hunt in a territory that they mark with their scent. They defend it against intruders. Like coyotes, foxes eat whatever they can catch—mice, ground squirrels, rabbits, birds, frogs, lizards, and insects. Foxes also seem to like fruit, even when other food is available.

Swift foxes are some of the fastest wild dogs in North America. They can run more than 25 miles (40 kilometers) an hour over short distances. Swift foxes are also known as kit foxes because of their small size. They are usually no more than 20 inches (51 centimeters) long and weigh from 4 to 6 pounds (1.8 to 2.7 kilograms).

With great bursts of speed, swift foxes can chase down almost any mouse, ground squirrel, cricket, or other small prey. Swift foxes also use their incredible quickness to zigzag their way to safety when chased by coyotes, red foxes, or other predators.