San Joaquin Kit Fox, Carly Hume

The San Joaquin Kit Fox

Vulpes macrotis mutica

 

The San Joaquin kit fox is the smallest of the canid species in North America (although the largest of the kit fox subspecies). The average male San Joaquin kit fox stands 12 inches high at the shoulder, 32 inches in length,12 inches of this being tail length, and weighing five pounds. Females are a slightly smaller. The footpads are characteristically small in this subspecies, as are their long legs and large ears set close together. The most distinct feature of the San Joaquin kit fox, and the feature that usually prevents accidental maltreatment, is the black tip of their tail, which is usually carried low and tapers to a slightly forward. In summer the fox’s fur is yellowish in color, and grays during the winter, becoming thicker while the white underside turns to beige.

San Joaquin kit foxes require dens for reproduction, shelter, and protection, which can be a limiting factor to their survival. Often the dens are locating in areas of rich, fertile soils which are attractive to land-owners for agricultural development, especially irrigated croplands. The kit fox must use small remnants of native habitat interspersed with patches of development, only if there are dispersal corridors, decreased habitat disturbance and a sufficient prey-base. Prey includes kangaroo rats, white-footed mice, California ground squirrels, black-tailed hares, ground-nesting birds, chukar, insects, which are supplemented with grass vegetation. San Joaquin kit foxes have a wild life expectancy between 7-8 years, with reproduction being dependent on their prey sources availability Kit foxes are also subject to predation or competitive endangerment by the coyote, nonnative red foxes, household dogs and bobcats. The red fox has similar den adaptation and prey base, creating direct competition between the two species.

 

Prior to 1930, the kit fox’s native range included much of the San Joaquin Valley, from southern Kern County north east Contra Costa county on the Valley’s west side and the Stanislaus county on its east. By 1930, only half of its native range remained, focused in the southern and western San Joaquin valley and foothills. By 1979 only 6.7% of land south of Stanislaus County remained available to the kit fox for habitat and reproduction. The largest extant populations are in western Kern County and on the Carrizo Plain Natural Areas in San Luis Obispo County. The most northerly concentrations are in the Antioch area of Contra Costa County.

 

The San Joaquin kit fox has had several historic waves of mortality causes. From the 1930-70s researches implicated habitat degradation and fragmentation associated with agricultural, industrial and urban developments in the San Joaquin Valley. Extensive land conversion in this area began in the mid 1800’s with the Arkansas Reclamation Act. Livestock grazing is not thought to be detrimental to kit foxes but may alter the numbers of different prey species. Increased traffic-related mortality due to an abundance of roads being built for petroleum field mining in the San Joaquin Valley, has also been reported. Kit foxes tend to live near riparian areas for denning, which are often adjacent to towns such as Tulare, Visalia, Maricopa, Taft, McKittrick and Bakersfield.

 

In 1967 the San Joaquin kit fox was listed as endangered by the U.S. Department of the Interior and by the State of California in 1971, and a recovery plan was approved in 1983. A multi-agency acquisition is underway which would secure 60,000 acres straddling Western Merced, Stanislaus and eastern Santa Clara counties. The species has been heavily studied and its life history and ecology documented in its surviving habitats. Additionally there have been enhanced habitat evaluation, kit fox relocation, supplemental feeding, and coyote control as means of enhanced recovery. Following the 1983 plan only three surveys for distribution have been conducted, two in the northern range of the fox and one in western Madera County. Large-scale demographic surveys have been conducted on the Carrizo Plain in San Luis Obispo County, as well as in Southern San Joaquin Valley. Although it has been listed for over 30 years its status throughout much of its historical range in San Joaquin Valley is poorly known, especially since much of this range occurs on privately owned land. CSU Stanislaus has collected detailed geospatial data for the species. Including proposed areas where connectivity and linkages should be promoted.



The Carrizo Plains Badlands

 

The 1983 Recovery Plan operated on two different strategic levels of acquiring new information of the kit fox’s life history, demographics and range while also continuing and expanding recovery actions. These actions are focused on creating a viable complex of kit fox populations (a viable metapopulation) on private and public lands in its geographic range. Kit foxes serve as an umbrella species in their ecologies, requiring large areas to survive in and benefitting many other species. They can have dramatic short-term population fluctuations. A second recovery strategy hinges on the protection and management of three geographically-distinct core areas of concentrated kit fox populations. These three core population areas are:

 

1.    Carrizo Plains Natural Area, San Luis Obispo County

2.    Natural lands of western Kern county

3.    The Ciervo-Panoche Natural Area of western Fresno and eastern San Bernardino counties

 

The continued research and data collection of San Joaquin kit fox populations and their interactions within their ecosystems and across adjoining ecologies, and how these relations are being affected by human populations is a continuing process that will determine the species.

 

Works Cited

 

U.S. Fish & Wildlife Service. 1998. Recovery plan for upland species of the San Joaquin Valley. Region 1. Portland, OR. 319 pp.