BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Urocyon cinereoargenteus | Gray Fox 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Diurnal Activity:  Gray foxes are more active at night and at dusk than
during the day.  Activity levels decrease sharply at sunrise, and
increase at sunset [17,18].  Gray foxes usually leave their daytime rest
area shortly before sunset, investigate the immediate area, and then
move purposefully to a foraging area.  Close to sunrise they usually
move back to a daytime resting area.  Gray foxes usually change resting
sites every day once vegetative cover is abundant in late spring; sites
are reused in winter [17].

Breeding Season:  Gray foxes usually breed from late winter to early
spring; dates of mating activity vary with latitude and elevation.  In
southern Illinois breeding occurs from late January to February; in
Wisconsin breeding occurs from late January to March [9], and in Oregon
mating occurs from mid-February to March [23].  Where gray fox is
sympatric with red fox (Vulpes vulpes), gray foxes breed 2 to 4 weeks
later than red foxes.  Gray foxes are assumed to be monogamous, but
direct evidence is lacking [9].  There is only one litter per year [35].

Gestation and Development of Young:  Gestation periods have been
variously reported as ranging from 53 to 63 days; Fritzell [10] reported
gestation in captivity lasted 59 days.  Mean litter size is 3.8, ranging
from 1 to 7.  Development has not been well studied [9].  Young are born
blind and nearly naked.  Eyes open about 9 days after birth.  The pups
nurse for over 3 weeks.  Solid food is fed to the pups before they are
completely weaned with the male beginning to bring food to the pups at
about 2 to 3 weeks.  Pups begin to fend for themselves at about 3
months; families disperse in late summer and autumn [23].

Population Structure:  Root and Payne [33] determined that the majority
of animals in a southwestern Wisconsin gray fox population were under 1
year old.  They concluded that gray foxes are "an annual crop."  The
majority of female gray foxes breed their first year [33].

Mortality and Longevity:  In the Central Valley of California, two of
four radiotracked gray foxes were killed by cars [11].  In east-central
Alabama, a population of gray foxes was tagged and monitored for causes
of mortality.  Canine distemper was the most frequent cause of death,
followed by trapping, automobile collision, and infectious canine
hepatitis.  Canine distemper was probably a localized cause of mortality
in this area; it is not expected that most gray fox populations suffer
the same rate of distemper deaths [27].  Maser and others [23] stated
that collision with automobiles is rare in Oregon; the major causes of
gray fox mortality are hunting and trapping.  They listed a probable
maximum longevity in the wild of 6 years.  The oldest captive gray fox
lived less than 8 years [23].


PREFERRED HABITAT : 
Gray foxes are most closely associated with deciduous forest,
particularly where it is in contact with disturbed or brushy habitat
[9,23,35].  They are usually found near surface water [29].  Preferred
habitat includes shrublands and brushy woodlands on hilly or rough
terrain.  In areas where gray foxes and red foxes occur together, gray
foxes prefer mixed woods with dense underbrush.  In the absence of red
foxes, gray foxes prefer other habitats [35].

In New England gray foxes are associated with dense northern hardwood or
mixed forests, thickets, and swamps.  Preferred habitat includes a
mixture of fields and woods [7].  In Wisconsin gray foxes were most
abundant near brush-covered bluffs where woods and farmland were well
interspersed [28].  From Virginia to southern Georgia optimal gray fox
habitat consists of woodland-farmland edge; post oak woodlands are also
good gray fox habitat [9].  In southern Georgia gray foxes are most
abundant in mixed woods and cultivated areas, less abundant in pine
savanna, and least common in mixed woods with dense underbrush [35].  On
the Coastal Plain most gray fox captures occurred in tall
weed-broomsedge (Andropogon virginicus)-dominated habitats and
cultivated areas.  There were relatively few captures on forested sites;
this difference from gray fox preferences in the majority of its range
was attributed to the absence of red foxes [24].

In the western states gray fox habitats include rocky hillsides,
mountainsides, and washes [35].  In Oregon gray foxes prefer mixed
hardwood and mixed conifer-hardwood habitats; they are present in
riparian hardwood, headland prairie, headland shrub, and tanoak
(Lithocarpus densiflorus) habitats [23].  In the Central Valley of
California, one gray fox spent most of its time in old fields and
human-use areas, one spent most of its time in agricultural areas, and
two spent most of their time in riparian areas.  None of the foxes used
areas of open dirt [11].  In California gray foxes were most abundant
from 3,800 to 5,000 feet (1,150-1,525 m) elevation [15].  In
northwestern California Douglas-fir forests, gray foxes were present in
similar abundances in all forest seres, but there were slightly fewer
gray foxes in mature timber [39].

Home Range:  Gray foxes tracked from May through August, 1980 and
January through August, 1981, had a monthly average home range of 740
acres (299 ha), and an average composite home range of 1,700 acres (676
ha).  Some individuals occupied the same general area for extended
periods, but home ranges tended to shift from month to month.  Only a
fraction of the home range is used on a given night [18].  The composite
home ranges of four radio-tracked gray foxes varied from 262 to 425
acres (106-172 ha).  Gray foxes are apparently solitary in the
nonbreeding seasons [17].  In Wisconsin gray fox home ranges vary from
0.24 to 1.2 miles (0.40-2 km) in diameter [32].  Lord [22] estimated
gray fox home range diameter of 1.9 miles (3.2 km).  Trapp [34] reported
an annual home range average of 0.2 square mile (0.52 sq km).

Territoriality:  Gray fox territoriality is not well defined.
Territories are marked with urine and feces, but in many areas home
ranges overlap considerably.  Family aggregates are formed so that
individual territories overlap; family aggregates do not overlap [18].


COVER REQUIREMENTS : 
Gray foxes tend to escape their enemies by finding cover rather than
depending on speed (as do red foxes) [23].  Dense vegetation is
important as diurnal resting and escape cover [18].  They climb trees
for use as resting and escape cover [23].  Their climbing ability
extends to saguaro (Carnegiea gigantea); one gray fox was observed
resting 15 feet (4.6 m) above ground on a saguaro limb [6].

Den sites include hollow logs and trees, rock outcrops, underground
burrows (usually the abandoned den of some other species), cavities
under rocks, abandoned buildings, wood or sawdust piles, and brush
[9,23].  Dens have been found up to 20 feet (9.1 m) above ground in tree
hollows.  Underground dens have usually been excavated by animals of
other species, but gray foxes occasionally dig dens in loose soil [35].

Den Use:  Dens are used throughout the year, but primary use is during
whelping season.  Dens are usually located in brushy or wooded habitats.
In Wisconsin most gray fox dens were on east-, southeast-, or
south-facing slopes [9].  Leaves, grass, fur, and other soft materials
are added to dens [23].


FOOD HABITS : 
Gray foxes are omnivorous, opportunistic feeders; they prey mainly on
small mammals, but fruit and invertebrates form a substantial portion of
the diet.  In the central United States cottontails (Sylvilagus spp.)
formed the major portion of the gray fox winter diet.  Other mammals
taken in noticeable numbers include voles (Microtus spp.), mice
(Peromyscus spp.), woodrats (Neotoma spp.), and cotton rats (Sigmodon
spp.).  Invertebrates increase in importance in the spring.  With
seasonally advancing vegetative growth and development, plant material,
particularly fruit, increases in gray fox diets, sometimes comprising up
to 70 percent by volume [10].  Grasshoppers (Orthoptera), beetles
(Coleoptera), and butterflies and moths (Lepidoptera) are the preferred
invertebrates; plant materials include fruits, nuts, grains, and
grasses.  Carrion is eaten opportunistically [35].  In some areas birds
(nestlings and eggs), particularly ground-nesters, are taken by gray
foxes; in Texas wild turkey (Meleagris gallopavo) nests were broken up
by gray foxes [3].

In a riparian area in the Central Valley of California, a gray fox ate
mostly ring-necked pheasant (Phasianus colchicus), California ground
squirrels (Spermophilus beecheyi), California voles (Microtus
californicus), and berries [11].  In Oregon primary prey items include
mice, pocket gophers (Thomomys and Geomys spp.), kangaroo rats
(Dipodomys spp.), woodrats, ground squirrels (Spermophilus spp.),
chipmunks (Tamias spp.), brush rabbit (Sylvilagus bachmanii), and birds
including domestic poultry.  Other food items include grasshoppers,
beetles, manzanita (Arctostaphylos spp.) berries, juniper cones, and
cascara (Rhamnus purshiana) berries [23].  In the Sonoran Desert the
fruit of the California palm (Washingtonia filifera) forms a substantial
portion of the gray fox winter diet [2].  In eastern Tennessee plant
foods included persimmon (Diospyros virginiana), black cherry (Prunus
serotina), blackberry (Rubus spp.) , and cancerroot (Conophilus
americana).  The most common vertebrate prey determined in scat analysis
(by volume) was eastern cottontail (Sylvilagus floridana), followed by
white-tailed deer (Odocoileus virginiana), presumably as carrion, and
rodents [14].


PREDATORS : 
Adult gray foxes have few predators, but are occasionally taken by
golden eagle (Aquila chrysaetos), coyote (Canis latrans), and bobcat
(Lynx rufus) [35]; pups are taken by bobcat, great horned owl (Bubo
virginianus), and possibly large hawks [23].


MANAGEMENT CONSIDERATIONS : 
Gray fox pelts are of some value but are not as valued as those of red
fox [23].  Trapping increases and decreases with pelt values; in a 1987
report it was mentioned that sales in the United States had increased
dramatically in the last decade.  The gray fox has "furbearer"
management status in many states [13,38].

Population Status:  The gray fox is characterized by widespread, healthy
populations in most areas.  Habitat availability may limit its
distribution, but lack of habitat does not appear to pose an immediate
threat [13].  Gray foxes are uncommon to common in New England [7].
Reported population densities range from 1 to 27 per square mile [35].

Gray foxes are considered pests by many farmers who raise domestic
poultry; biologists claim that this damage is usually overstated and
that gray foxes benefit agriculture by controlling rodent and rabbit
populations [23].  In northern bobwhite (Colinus virginianus) management
areas only a small number of gray foxes (0.7%) were found to have
northern bobwhite remains in their stomachs [26].

Gray foxes commonly carry rabies, most frequently in the Appalachian
states (KY, TN, VA, WV) [4].  They also carry tularemia [23] and canine
distemper which is not as virulent in gray foxes as it is in domestic
dogs (Canis familiaris) [38].


REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Urocyon cinereoargenteus | Gray Fox