San Joaquin Kit Fox
Vulpes macrotis mutica
Listed as Endangered by the Federal Government and listed as Threatened by the State of
California
Life History
The San Joaquin kit fox is one of the eight recognized subspecies of kit fox. It
resembles a small lanky dog with disproportionately large ears; total length is about 32 inches,
which include a 12-inch black-tipped tail. Coloration of the kit fox ranges from light buff to
grayish along the back and tail; gray, rust, or yellowish along the sides; and white along the
belly.
The San Joaquin kit fox was historically distributed over a large portion of central
California, extending roughly from southeastern Contra Costa County south along the eastern
flanks of the Interior Coast Range to the southern San Joaquin Valley, including major
portions of western Kern County and Tulare County. San Joaquin kit fox were also
distributed through adjacent valleys, foothills, and plains, including portions of San Luis
Obispo County, Monterey County, and the Santa Clara Valley on the western side of the
Interior Coast Range.
San Joaquin kit foxes are nocturnal, using dens that have been excavated in loose soil; individual animals may utilize from three to 24 separate dens within. There may be one to 36 entrances to any one den, extending into several individual
tunnels and chambers reaching depths of up to 10 feet. Man-made structures
such as culverts and pipes may also be utilized as dens in those areas with a
shortage of dens. Typically, den entrances are higher than wide and are sufficiently small to
prevent access by large carnivores such as coyotes. Dimensions of the entrances are generally
about eight to ten inches in height and less than eight inches in width but may
be as narrow as four inches. Burrows of other animals, particularly California ground
squirrels (Spermophilus beecheyi) are opportunistically enlarged and utilized as den sites by
San Joaquin kit foxes. Although occupied dens may show freshly excavated
soil, scats, and prey remains, such obvious signs are frequently absent.
Individual San Joaquin kit foxes have an average home range of one to two square
miles. Courtship and mating occur in December and January and
the pups are typically born in February and March, dispersing at around five months of age. Survival rates of kit fox pups are low; about 75 percent die
before the age of eight months.
Mortality for this species has been documented from attacks by coyotes, golden eagle,
road kills, conversion of habitat, shooting, drowning, entombment, pneumonia, and starvation.
Additionally, the use of rodenticides has resulted in secondary mortality, since kit foxes are
vulnerable to poisoning through consumption of poisoned rodents.
Habitat conversion for agricultural and a variety of urban uses has been the principle
cause of significant kit fox population declines and the reason for both state and federal listing
of this species.
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