Geographic Range
Gray foxes are found in the lower half of the Nearctic and northwestern part of the
Neotropics. More specifically, their range spans from southern Canada to Venezuela
and Columbia, excluding portions of the Great Plains and mountainous regions of northwestern
United States and eastern coast of Central America.
- Biogeographic Regions
- nearctic
- neotropical
Habitat
Gray foxes prefer to live in deciduous forests interspersed with brushy, woodland
areas. Many populations thrive where woodlands and farmlands meet; however, red foxes
(
Vulpes vulpes
) are known to frequent agricultural areas more than gray foxes. Proximity to water
is a key feature of preferred habitat as well. Dens are usually located in hollow
trees or logs, in crevices between and under large rocks, and in underground burrows.
Dens have also been found in the lower forest canopy, 10 m above the forest floor,
in hollow tree trunks and limbs. Gray foxes are the only member of the
Canidae
family that can climb trees. They are most often found below 3000 m in elevation.
- Habitat Regions
- temperate
- terrestrial
- Terrestrial Biomes
- savanna or grassland
- forest
- scrub forest
Physical Description
Fully grown gray foxes display a mix of white, red, black and gray fur. However,
new born pups tend to be dark brown. Gray foxes are medium-sized canids with elongated
bodies and relatively short legs. They usually weigh between 3 and 5 kg, but can
weigh up to 9 kg. Individuals at high elevation are slightly larger than their low
elevation counterparts. Males are slightly larger than females, and skeletal measurements
show that males have longer pelvises and calcanea, wider scapulae and more robust
limb bones. In general, gray foxes can grow up to 1 m in length. Their tail makes
up approximately one-third of their total body length and has a distinct black stripe
along the dorsal surface and a black tip. The top of the head, back, sides, and rest
of the tail are gray with the belly, chest, legs and sides of the face being reddish
brown. The cheeks, muzzle and throat are white. Gray foxes have oval-shaped pupils
and the area around the eyes has a thin black stripe from the outside corner of the
eye to the side of the head. Additionally, a thick black stripe runs from the inside
corner of the eye, down the muzzle to the mouth. They are sometimes misidentified
as red foxes (
Vulpes vulpes
); however, red foxes have slit-shaped eyes, larger feet, longer legs, and a leaner
body.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
Reproduction
Gray foxes are solitary animals that socialize only during mating season. They are
typically monogamous, although in rare cases polygamy and polyandry occur. For a
short period of time after parturition, family groups consisting of male, female,
and young exist. Male-female pairings form in the fall with breeding occurring in
the winter. During October and September, attracting mates become more competitive
and males usually display more aggression while retaining and defending mates. Similar
to domestic dogs (
Canis lupus familiaris
), gray foxes have scent glands just inside the anus. Additional scent glands are
found on their face and the pads of their feet. Although these glands are primarily
used to demarcate territory, they may also be used to attract potential mates.
- Mating System
- monogamous
Breeding season varies with geographic region, elevation, and habitat quality. Breeding
occurs in yearly cycles, beginning in January through late February, continuing into
March. In some areas (e.g., Texas), breeding has been observed as early as December.
Parturition occurs after about 2 months of gestation, peaking in April, with an average
litter size of 3.8 pups, which weigh about 86 g at birth. Pups are typically weaned
by 3 to 4 weeks, but may not be completely weaned until 6 weeks. Both genders are
sexually mature by 10 months old, soon after dispersal. Annual onset of spermatogenesis
occurs earlier and last longer than estrus. If they have been exposed to significant
levels of the synthetic estrogen, diethylstilbestrol, females may experience delayed
fertilization.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- viviparous
Both genders take care of offspring in gray foxes. Before birth, males do a majority
of the hunting, while females look for and prepare a suitable den. Weaning begins
around 2 to 3 weeks of age. Pups begin eating solid food around 3 weeks old, which
is primarily provided by the father. Parents teach pups how to hunt at around 4 months
old. Until then, both parents prey for food separately, and pups practice their hunting
skills by pouncing and stalking, which is primarily taught by the father. Pups depend
on their parents for defense until about 10 months old, at which point they become
sexually mature and disperse.
- Parental Investment
- precocial
- male parental care
- female parental care
-
pre-hatching/birth
-
provisioning
- male
-
provisioning
-
pre-weaning/fledging
-
provisioning
- male
- female
-
protecting
- male
- female
-
provisioning
-
pre-independence
-
provisioning
- male
- female
-
protecting
- male
- female
-
provisioning
Lifespan/Longevity
Lifespan for both captive and wild gray foxes ranges from 6 to 8 years. However, the
oldest recorded wild gray fox was 10 years old at time of capture, and the oldest
captive gray fox lived to be 12 years old.
Gray foxes generally live for 6 to 8 years. The oldest wild gray fox was 10 years
old when captured. The oldest gray fox in captivity lived to be 12 years old.
Behavior
Gray foxes remain solitary for the majority of the year. During winter, gray foxes
socialize with their mate and with their offspring after parturition. They are primarily
nocturnal, but have been occasionally spotted during daytime. Some of the physical
traits unique to gray foxes (e.g., short legs and retractable claws) have lead researchers
to suggest that they are one of the more primitive members of the
Canidae
family.
- Key Behaviors
- scansorial
- terricolous
- troglophilic
- nocturnal
- motile
- nomadic
- daily torpor
- solitary
- territorial
Home Range
Home ranges vary between 1 and 7 km^2, depending on geographic range, with an average
home range size of 2.1 km^2. Gray foxes use only small portions of this range each
day.
Communication and Perception
Like other members of the family
Canidae
, gray foxes are able to communicate by barking and growling. Males have been observed
trying to attract potential mates by raising their hind leg to show off their genitalia.
As juveniles, gray foxes commonly play fight. As adults, they use their scent glands
to mark territories and food sources.
- Other Communication Modes
- pheromones
- scent marks
Food Habits
Gray foxes are omnivorous. Although they prey on small vertebrates, fruit and invertebrates
also form a substantial part of their diet. Cottontails (
Sylvilagus floridanus
), mice (
Peromyscus
), woodrats (
Neotoma
), and cotton rats (
Sigmodon hispidus
) form the majority of their winter diet. In the Sonoran Desert, the fruit of the
California palm makes up a significant portion of their winter diet. With the onset
of spring, fruits become an increasingly important part of their diet, at times making
up 70% of its diet. Invertebrates, fruits, nuts, and grains also increase in importance
during the spring. Grasshoppers (
Orthoptera
), beetles (
Coleoptera
), and butterflies and moths (
Lepidoptera
) are the preferred invertebrates. When available, gray foxes may also feed on carrion.
When gray foxes accumulate an excess amount of food, they cache it by digging a hole
with their forepaws and burying it. Immediately afterwards, they mark it with urine
or using their scent glands on their paws and tail in an effort to ward off other
animals as well as to make it easier to relocate.
- Primary Diet
-
carnivore
- eats terrestrial vertebrates
- insectivore
- scavenger
- herbivore
- omnivore
- Animal Foods
- birds
- mammals
- eggs
- carrion
- insects
- terrestrial non-insect arthropods
- Plant Foods
- roots and tubers
- seeds, grains, and nuts
- fruit
- Foraging Behavior
- stores or caches food
Predation
Gray foxes primary predators include bobcats (
Lynx rufus
), golden eagles (
Aquila chrysaetos
), great-horned owls (
Bubo virginianus
) and coyotes (
Canis latrans
). In the southern region of the United States, gray fox abundance is highly dependent
on
coyote
abundance. Other than death by natural causes, humans may be responsible for the
greatest number of deaths and therefore may be their largest threat. Hunting, trapping
and retaliatory killings by livestock ranchers are not uncommon. Unlike red foxes
(
Vulpes vulpes
), which evade predators by using their superior agility, gray foxes escape by hiding
under cover (e.g., brush piles). When escaping terrestrial predators, gray foxes can
use their retractable claws to climb trees.
Ecosystem Roles
Gray foxes have a small, but important role in our ecosystems. Their feeding habits
allow them to influence small rodent (
Rodentia
) populations by maintaining a steady predator-prey relationship. They serve as a
host to many parasitic arthropods, including fleas (
Siphonaptera
), lice (
Phthiraptera
), ticks (
Ixodida
), chiggers (
Trombidiformes
), and mites (
Acari
). Gray foxes are also host to a number of internal parasites including nematodes
(
Nematoda
), flukes (
Trematoda
), tapeworms (
Cestoda
), and acanthocephalans (
acanthocephala
)
- nematodes ( Nematoda )
- flukes ( Trematoda )
- tapeworms ( Cestoda )
- acanthocephalans ( acanthocephala )
- fleas ( Siphonaptera )
- lice ( Phthiraptera )
- ticks ( Ixodida )
- chiggers ( Trombidiformes )
- mites ( Acari )
Economic Importance for Humans: Positive
Gray foxes are hunted and trapped for their pelt. Compared to red fox (
Vulpes vulpes
), gray fox pelts are less desirable because the hairs are coarser and shorter. Gray
foxes may also help control the abundance of certain agricultural pests, including
rodents (
Rodentia
) and rabbits (
Leporidae
).
- Positive Impacts
- body parts are source of valuable material
- controls pest population
Economic Importance for Humans: Negative
Gray foxes are considered a problem species by poultry farmers. However, red foxes
(
Vulpes vulpes
) are commonly misidentified as gray foxes, and commonly attack and kill poultry as
well. In addition, gray foxes carry zoonotic diseases that could be a potential health
threat to humans (e.g., rabies) and domestic dogs (
Canis lupus familiaris
; e.g., tularemia and canine distemper).
- Negative Impacts
-
injures humans
- causes disease in humans
- carries human disease
- causes or carries domestic animal disease
Conservation Status
Gray foxes are abundant throughout most areas in the lower two-thirds of North America. They have no special conservation status at this time. Although they are trapped and hunted by humans, there does not appear to be any immediate threat.
Additional Links
Contributors
Long Vu (author), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff, Gail McCormick (editor), Animal Diversity Web Staff, Phil Myers (editor), University of Michigan-Ann Arbor.
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- scrub forest
-
scrub forests develop in areas that experience dry seasons.
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- monogamous
-
Having one mate at a time.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- young precocial
-
young are relatively well-developed when born
- male parental care
-
parental care is carried out by males
- female parental care
-
parental care is carried out by females
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- nomadic
-
generally wanders from place to place, usually within a well-defined range.
- solitary
-
lives alone
- territorial
-
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- pheromones
-
chemicals released into air or water that are detected by and responded to by other animals of the same species
- scent marks
-
communicates by producing scents from special gland(s) and placing them on a surface whether others can smell or taste them
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- carrion
-
flesh of dead animals.
- stores or caches food
-
places a food item in a special place to be eaten later. Also called "hoarding"
- causes disease in humans
-
an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).
- causes or carries domestic animal disease
-
either directly causes, or indirectly transmits, a disease to a domestic animal
- carnivore
-
an animal that mainly eats meat
- insectivore
-
An animal that eats mainly insects or spiders.
- scavenger
-
an animal that mainly eats dead animals
- herbivore
-
An animal that eats mainly plants or parts of plants.
- frugivore
-
an animal that mainly eats fruit
- granivore
-
an animal that mainly eats seeds
- omnivore
-
an animal that mainly eats all kinds of things, including plants and animals
References
Brant, S. 2002. "Gray Fox" (On-line). Accessed March 29, 2009 at http://www.blueplanetbiomes.org/grey_fox.htm .
Campbell, C. 2006. "Urocyon cinereoargenteus - Grey fox" (On-line). World of the Wolf. Accessed March 29, 2009 at http://www.naturalworlds.org/wolf/canids/Urocyon_cinereoargenteus.htm .
Davis, W., D. Schmidly. 1994. "The Mammals of Texas - Online edition" (On-line). Common Gray Fox. Accessed March 29, 2009 at http://www.nsrl.ttu.edu/tmot1/uroccine.htm .
Fritzell, E., K. Haroldson. 1982. Urocyon cinereoargenteus. Mammalian Species , 189: 1-8.
Postanowicz, R. 2008. "Lioncrusher's Domain" (On-line). Grey Fox. Accessed March 29, 2009 at http://www.lioncrusher.com/animal.asp?animal=18 .
Quinn, P. 2006. "Illinois Department of Natural Resources" (On-line). Accessed March 29, 2009 at http://www.dnr.state.il.us/orc/wildlife/furbearers/gray_fox.htm .
Southwest Wildlife. 2007. "Southwest Wildlife" (On-line). The Gray Fox. Accessed March 29, 2009 at http://southwestwildlife.org/pdf/foxindepth.pdf .