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U.S. Department of Health and Human Services

Animal & Veterinary

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FOX FACTS

by Tania Woerner, V.M.D.
FDA Veterinarian Newsletter March/April 1998 Volume XIII, No II

Foxes are one of the most widespread species, covering six of the seven continents and many different countries and climate zones. Foxes did live in North America before the European Discovery in 1491; however, it was the importation by the British of foxes (mainly for hunting and fur trapping) that established the population of foxes in North America and Australia. The fox prefers gently rolling farmland with sparsely wooded areas and running streams, but the fox is remarkably adaptable and manages to survive and prosper in urban and suburban areas, living in culverts, basements and garden sheds and eating human refuse.

The beautiful russet-coated red fox is a full member of the dog (Canidae) family; however, because of the way it stalks and pounces on its prey, many people think of foxes as more cat-like. Foxes will bury their food much like a dog and return for it later when food supplies are limited. Like humans, foxes are omnivorous and feed on fruit, berries, birds, mice, voles, insects and other invertebrates, especially earthworms! A study conducted on urban foxes living around London found that foxes had even consumed the discarded remains of various ethnic human foods!

The average life span of a fox is about 3 years with a maximum known lifespan of 12 years. Predators of foxes are coyotes, cougars, wolves and wild dogs; however, the most vicious predator is man. In the past foxes were considered vermin and killed for sport and fur. Now humans threaten foxes in a more indirect fashion by over-development. Man's destruction of the foxes' natural habitat has forced foxes to move into more urban areas, where the threat of traffic is greater, and residents often call upon the animal control authorities to eliminate them.

Courtship for foxes begins in mid to late December. When courtship begins, foxes will often be seen traveling in pairs or sometimes groups of three. Mating usually takes place in January or February; however, it can extend into April if the food supply is adequate. Since the gestation period is 52 days, fox kits are typically born in March through April. A typical red fox family consists of the dog fox and a vixen, plus up to four "helper" females which may or may not breed and are subordinate to the breeding vixen. Often these younger foxes are the vixen's daughters. Each family of foxes needs several safe den sites in which to raise their cubs in addition to safe resting spots outside the den. The family domain is established by the dog fox by marking his territory. The scent of the dog fox alerts other foxes to stay clear of this territory. It is common for a family to have several dens within their territory. Prior to parturition, the mated pair selects a den, called the natal den, in which to bear the kits. This den is usually larger than the other available dens and always has several exits.

Fox litters can be as small as one kit, or as large as thirteen, but the average is five. If a mother and an older daughter produce a litter at the same time, the daughter will often surrender her kits to her mother, and all the kits are raised together as a litter, with the older daughter assisting in rearing the kits.

Kits are born blind, with short grey fur. Within ten days, their eyes are open, and by three weeks they are playing outside the den. It is not uncommon for urban and rural foxes to move their kits to alternate den sites several times while the kits are maturing. Fox kits are playful and affectionate, and by five weeks of age they begin to explore outside of the den. By two months of age the fox kits are less dependent on their parents and begin to hunt on their own. Typically, October is the month when they begin to leave the den to find a domain of their own. Interestingly, not all fox kits leave in their first year; females are more likely to "stick around," sometimes until they are about two years old. Population density and food supply determine the timing of the dispersal of fox kits. When the population is dense and the food supply is scarce, they will strike out on their own at an earlier age and travel greater distances.

Once the kits have dispersed, the adults and remaining kits hunt on the same territory, but hunt and travel alone. The male and female foxes do not associate regularly until courtship begins again in December.