San Joaquin kit fox
(Vulpes macrotis mutica)
by Howard Clark - howard.clark.jr@gmail.com
The kit fox (Vulpes macrotis) is the smallest of the North American foxes, being about 25 percent smaller than the red fox (Vulpes vulpes). Kit foxes lack the band of coarse, black hairs, which run down the tail of the gray fox (Urocyon cinereoargenteus). The kit fox has comparatively large ears that are greater than 75 mm from notch to tip in adults (less than 75 mm in the swift fox, Vulpes velox) with dense, stiff, white hairs that almost cover the auricle opening (Christenson 1984, McGrew 1979, Waithman and Roest 1977, USFWS 1983).
The San Joaquin kit fox is the largest subspecies of Vulpes macrotis, the skull being larger in almost all dimensions and the occipital crest more pronounced in adults. The body is slender; adults being about 50.8 cm (20 in) long and 22.9-30.5 cm (9-12 in) tall at the shoulder. The tail is about 12 inches long, bushy, cylindrical in shape, and tapering toward the tip. The average weight is about 4.9 pounds, with males being larger (average 5.0 pounds) females (4.6 pounds). The color is generally darker than Vulpes macrotis macrotis. In summer San Joaquin kit fox coloration is light buff gray dorsally and white ventrally. Winter pelage is grizzled-gray dorsally, rusty to buffy-yellow laterally and white ventrally. The tail is light buff to buffy-gray with a conspicuous black tip. Legs and feet are long and slender and whitish in color. The soles of the feet are well haired (Christenson 1984, Waithman and Roest 1977, USFWS 1983, Morrell 1975, Knapp 1978).
The kit fox was originally described by Merriam in 1888 using the name Vulpes macrotis. The San Joaquin kit fox was named Vulpes muticus by Merriam in 1902. Grinnell in 1913 considered it a subspecies and used the name Vulpes macrotis muticus and later (Grinnell 1933) changed the subspecies name to mutica. Lechleitner (1969) and others treated it as a subspecies of the swift fox using the name Vulpes velox macrotis. Hall and Kelson (1959) and others noted the similarity between the two forms but chose the conservative course of full species status for each. Rohwer and Kilgore (1973) examined species from the interface zone between the two, favoring separate status for each. Thornton and Creel (1975) confirmed this conclusion based on differences in several external characteristics and blood serum and hemoglobin protein electrophoresis, supporting the name of Vulpes macrotis for the kit fox. Waithman and Roest (1977) clearly demonstrated that the San Joaquin kit fox is separable from other kit foxes based on size, as noted by Grinnell et al. (1937), cranial features, geography, and habitat type. Their conclusion is that the San Joaquin kit fox is a valid subspecies deserving the name Vulpes macrotis mutica (McGrew 1979, Waithman and Roest 1977).
The type locality of the San Joaquin kit fox is near Tracy, San Joaquin County, California, as noted by Merriam (1902). Specimens located at the U.S. National Museum of Natural History included 7 specimens from Tracy, San Joaquin County; 3 specimens from Alila and 1 specimen from Goshen, Tulare County; 1 specimen from Bakersfield, Kern County; and 3 specimens from Coalinga, Fresno County. At the University of California, Museum of Vertebrate Zoology, Berkeley, there are specimens from (location followed by number of specimens collected from each site): Shandon, San Luis Obispo County (1); Blackwells Corner (1), Keck’s Corner (7), and Rose Station (1), Kern County; and Panoche Creek (3), Mercy Hot Springs (2) and west of Firebaugh (9), Fresno County. At the California State Polytechnic University, San Luis Obispo, there are two specimens from Buttonwillow and the Snedden Ranch, Kern County. California State University at Fresno also has a collection of San Joaquin kit fox. Photographs or drawings are available from the California Department of Fish and Game, Sacramento, California and several other sources in the area (Waithman 1974).
The San Joaquin kit fox (Vulpes macrotis mutica) has been designated as Endangered pursuant to the Endangered Species Act of 1973 (50 CFR 17.11; P.L. 93-205, 87 Stat. 884; 16 U.S.C. 1531-1540), as amended. The subspecies has this status wherever found including the State of California. This subspecies is protected by the Lacey Act (P.L. 97-79, as amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import, export, transport, sell, receive, acquire, or purchase any wild animal (alive or dead including parts, products, eggs, or offspring): (1) in interstate or foreign commerce if taken, possessed, transported or sold in violation of any State law or regulation, or foreign law; or (2) if taken or possessed in violation of any U.S. law, treaty, or regulation or in violation of Indian tribal law. It is also unlawful to possess any wild animal (alive or dead including parts, products, eggs, and offspring) within the U.S. territorial or special maritime jurisdiction (as defined in 18 U.S.C. 7) that is taken, possessed, transported, or sold in violation of any State law or regulation, foreign law, or Indian tribal law.
Responsible Federal Agencies
USFWS: Responsible for the management and recovery, listing, and law enforcement and protection of this species.
BLM: Responsible for the law enforcement and protection of this species with applicable State and Federal laws on public land under their control (43 CFR 4140). Also responsible for management and recovery on Bureau of Land Management lands.
DOD: Responsible for the law enforcement and protection of this species with applicable State and Federal laws on public land under their control. Also responsible for management and recovery on Department of Defense lands.
USFS: Responsible for the law enforcement and protection of this species with applicable State and Federal laws on public lands under their control. Also responsible for management and recovery on Forest Service lands. The Forest Service is responsible for integrating management, protection, and conservation of Federally listed species into the Forest Planning process (36 CFR 219.19 and 219.20).
All Federal agencies have responsibility to ensure that any action authorized, funded, or carried out by that agency is not likely to jeopardize the continued existence of the species or result in the destruction or adverse modification of Critical Habitat (50 CFR 402), and to utilize their authorities to carry out programs for the conservation of the species.
STATE: California
DESIGNATED STATUS: Threatened
ADMINISTRATIVE AGENCY: Calif. Dept. of Fish and Game
STATE STATUTE: Endangered Species Act; Fish and Game Code, Chapter 1.5, Article 1, Sect. 2050.
The San Joaquin kit fox is listed by the United States in the Convention on Nature Protection and Wildlife Preservation in the Western Hemisphere Annex (1970).
67/03/11:32 FR 04001 Listed as Endangered, Preact 1
70/10/13:35 FR 16047/16048 Preact 7, Relisting
79/05/21:44 FR 29566/29577 Notice of Status Review
85/07/22:50 FR 29901/29909 Notice of Review
87/07/07:52 FR 25522 Notice of 5 year review completion
Prime habitat for the San Joaquin kit fox is the arid and semi-arid plains of the San Joaquin Valley floor, consisting of alkali sink, saltbush scrub and grassland plant communities. Other important types include foothill saltbush scrub, grasslands, intermittent stream banks and washes. Of lesser importance are lowland sinks subject to flooding and foothill woodlands at higher elevations (Christenson 1984, USFWS 1983). The alkali sink community consists of poorly drained barren playas and hummocks with salt-tolerant vegetation such as saltgrass (Distichilis spicata), seepweed (Suaeda fruticosa), iodine bush (Allenrolfea occidentalis) and a variety of annual flowering plants and grasses. It is doubtful that the original range of the San Joaquin kit fox included these wetland areas due to the limited sites that contained well-drained soils (most of the habitat of this type is saturated and has periodic flooding) for den sites. Saltbush scrub communities occur on better-drained soils and are dominated by desert saltbush (Atriplex polycarpa), interspersed with a variety of annual grasses and some annual flowering plants and other perennial shrubs. While alkali sink areas have been extensively converted to agriculture, the saltbush scrub areas are subject to even greater conversion (Christenson 1984, McGrew 1979, USFWS 1983, Knapp 1978, Morrell 1975, 1972). The high loss of optimal habitat to development has forced the kit fox into areas of secondary habitat (often this means areas of wetland types – alkali sinks and tule marshes). Foothills and hillside scrub, grassland and woodland habitats are generally on shallower soils making burrow excavation more difficult, thus less adapted to kit fox occupation. The foothill oak kit foxes sometimes occupy woodlands but they are better suited for the gray fox (Urocyon cinereoargenteus) (Christenson 1984, USFWS 1983, Morrell 1975, 1972). Kit fox may occupy intermittent streamside habitat and arid washes. Streamside vegetation habitat may be dominated by mesquite (Prosopis glandulosa), cottonwood (Populus fremontia), willow (Salix sp.) and quail bush (Atriplex lentiformis) (Christenson 1984, USFWS 1983, Morrell 1975, 1972). These areas are especially suitable if mixed with or adjacent to arid shrub or grassland habitats. Washes are used for foraging and sometimes denning in banks just above the wash floor (Morrell 1972, O'Farrell and McCue1981). Valley lowlands of tall grass associations are of reduced value to kit foxes because of saturated soils, periodic flooding and unsuitability for prey base animals. Only isolated, well-drained soils suitable for den excavation in these habitats may be occupied by kit foxes (Morrell 1975, 1972). Habitat requirements include loose textured soils for den excavation, an adequate prey base, and an arid climate. Soils of sandy clay and sandy loam, stone-free for about 3 to 4.5 feet of depth, are preferred. These are usually found in deep alluvial fans and floodplains. Adverse soil conditions include shallow soils over, high water tables, saturated soils, and impenetrable hardpan or caliche layers (Christenson 1984, USFWS 1983, Morrell 1975, 1972, O'Farrell and McCue1981). Climate typical of kit fox habitat consists of hot, dry summers of 38-118 degrees Farenheit (F) and cool, wet winters of 13-89 degrees F. Areas are subject to 1-12 inches of precipitation, usually between November and April, when lowlands are subject to seasonal flooding (USFWS 1983, Morrell 1975, 1972). These conditions are normally found at elevations up to about 3000 feet. Level areas are preferred, although kit fox may inhabit slopes up to 40 degrees. Natal or pupping dens are almost exclusively dug in areas of low relief, about 6 degrees of slope (Morrell 1972, O'Farrell and McCue1981).
San Joaquin kit foxes are tolerant of human activities that do not reduce denning sites. Light industrial development, including oil fields, primitive or limited road development, and limited urban development, allow for continued area use by kit fox. Kit foxes can be found close to urban areas and are known to inhabit portions of the California Aqueduct right-of-way. Bridges, culverts, and piles of pipe or other materials may be used for cover. Kit foxes may be found in association with agricultural areas such as pasture, hay, cotton, and sugar beet fields, fruit and nut orchards, and vineyards. The occurrence of kit fox in developed areas seems to be either quite marginal or merely incidental and dependent on the presence of an adequate prey base and nearby suitable denning areas (USFWS 1983, Morrell 1975, 1972, O'Farrell and McCue1981).
Food Habits
San Joaquin kit fox are primarily carnivorous; however, they also consume invertebrates and vegetation. Pups apparently nurse for one to two months. Following weaning they are fed primarily kangaroo rats (Dipodomys sp.) by their parents until they are about three or four months old. An adult pair will feed about 98 pounds of meat to five pups in two months. Sub-adults will consume about three ounces of meat per day and adults consume about twice that (USFWS 1983, Morrell 1975, 1972, O'Farrell and McCue1981). They apparently are opportunistic feeders, although some investigators believe kangaroo rats are a principal prey item. Kangaroo rat remains can be found in kit fox scats year-round in the San Joaquin Valley, while lagomorph remains occur mostly in spring and summer (Morrell 1975, 1972). In agricultural areas, desert cottontail rabbits (Sylvilagus auduboni) constitute the bulk of the diet (Morrell 1975, 1972). It is believed that kit foxes obtain moisture from their prey. However, a mostly protein diet would create a water deficiency. The explanation of their water maintenance is not known (USFWS 1983, Morrell 1975, 1972). Primary diet constituents based on scat analysis and remains found near burrows is as follows:
kangaroo rats Dipodomys ingens, D. nitratoides, D. heermanni
cottontail rabbit Sylvilagus auduboni
black-tailed hares Lepus californicus
California ground squirrel Spemophilus beecheyi
Also occurring frequently in scats are insects, and vegetation seeds and stems, including:
Scorpions Scorpionidae
Jerusalem crickets Stenopelmatus longispinus
Ants Formicidae
Grasshoppers Oedaleonotus enigma
Grasses Bromus sp.
Filaree Erodium cicutarium
Incidentally consumed are other small mammals including:
pocket mice Perognathus inornatus, P. flauus
deer mice Peromyscus maniculatus
harvest mice Reithrodontomys megalotis
San Joaquin antelope squirrel Ammospermophilus nelsoni
Gophers Thomomys bottae
Other insects (Insecta) and spiders (Arachnida); seeds and stems of other grasses and annual flowering plants; birds, including western meadowlark (Sturnella neglecta) and California quail (Lophortyx californicus); and lizards (USFWS 1983, Morrell 1975, 1972, O’Farrell 1980.). They are known to eat old, decaying meat and carrion from road-kills caused by motor vehicles (USFWS 1983, Morrell 1975, 1972).
San Joaquin kit foxes appear to have no foraging territorial behavior by individuals nor families. They do have family denning areas with home ranges of varying sizes depending on prey base abundance. Home ranges vary from about one to two square miles. Knapp, in a 1977 study, found minimum ranges of 120 acres to 1,851 acres in size. There may be from 1-6 kit foxes per square mile, indicating that a great deal of overlapping in home ranges can occur. Adults are usually solitary from June until October. From October to June they are paired and establish natal dens. The pups remain close to natal dens until the family groups separate in summer. There is movement from home ranges for breeding and population dispersal (USFWS 1983, Morrell 1975, 1972, Laughrin 1970).
San Joaquin kit fox are generally nocturnal, although some diurnal activity does occur, especially when caring for young. Pups can often be seen in playful activity during the daytime near the entrances to their natal den. This is most common between two and six o'clock in the afternoon during the spring season. Otherwise, adults may occasionally appear above ground during the daytime. This activity is mostly in the summer and fall. Normal activities begin at sunset and continue off and on throughout the night. Kit foxes do not hibernate during the winter (Morrell 1972).
San Joaquin kit foxes have a very limited area of travel. They are not known to be migratory, except for short movements during population dispersal and seeking of a mate for breeding purposes. Unlike the desert kit fox, which has been known to travel 20 miles, this subspecies is believed to move less than 1.25 miles on the average. Knapp (1977) found individual home ranges with maximum distances between farthest points traveled of 0.5 miles to 3.5 miles. Pups will generally leave their natal den area to find a place to inhabit. An adult may move from the denning area to pair with a new mate in another area (USFWS 1983, Morrell 1975, 1972, O’Farrell and Gilbertson 1979).
Dens provide the only substantial shelter for the San Joaquin kit fox. Artificial dens include culverts, well casings, abandoned pipelines, and man-made burrows. Larger natal dens are occupied by single-family groups during the reproduction period of October or November through May or June. Other smaller individual dens are used by solitary kit foxes during the balance of the year (USFWS 1983, Morrell 1975, 1972, O’Farrell and McCue 1981).
Usually kit foxes excavate their dens in loose textured soil at elevations between 350 and 2,950 feet in areas of low-to-moderate relief, averaging about 20 degrees of slope. Natal dens are found on flatter terrain, averaging about 6 degrees of slope. Large dens are often found in association with abandoned ground squirrel mounds. In hardpan soils, kit foxes may use abandoned badger burrows which have already penetrated the harder substrate. Dens are typically not found in shallow soils over bedrock nor areas of shallow water table (USFWS 1983, O’Farrell and McCue 1981).
Den entrances are about 10-18 inches deep and 12-36 inches wide. Natal dens have up to 18 entrances, averaging six, while solitary dens have three or fewer. Most commonly, solitary dens are comprised of two entrances. Entrance tunnels are quite small, measuring 8 to 11 inches high and 4 to 6 inches wide. Openings of this size would prohibit entry of predatory coyotes and badgers. Inside tunnel diameters are further reduced, being 5 to 6 inches high and 6 to 8 inches wide. Enlarged areas inside dens are up to 10 inches high. Den passages are constructed to depths of 50 or more inches below the ground surface and may extend 15 feet horizontally from entrances. Active dens can be identified by fresh dirt about the entrance, along with scats and prey remains. Nearby grass may also be matted from trampling. Vacant kit fox dens may become occupied by burrowing owls (Athene cunicularia) or other animals. Kit fox dens are not shared, but occupied by individual foxes or single-family groups. Exceptions to this are rare. A single family may move from one den to another several times during the time pups are being raised. This may be for utilizing a new prey base or to escape ectoparasite populations.
An individual kit fox may use from 3 to 24 different dens. As a result, most dens are vacant at any one time. One family, an adult with a different mate each year, and two of their offspring, occupied 41 different dens during a fifteen-month period. Seven pairs occupied 71 different dens during that same period. Conversely in study areas being subjected to conversion to agriculture, there were three dens per fox (USFWS 1983, Morrell 1975, 1972).
Density of kit fox dens varies from 11 to 29 per square mile. Of this, there are 0.29 to 1.78 active dens per square mile, averaging 0.81. On the San Joaquin Valley floor kit fox habitat, there is an average of 5.8 dens per square mile, of which 1.0 is active. In foothill habitats the average is 3.5 dens per square mile with 0.6 active (USFWS 1983, Morrell 1975, 1972).
San Joaquin kit fox mated pairs occupy large dens with multiple entrances, sometimes very complex networks of tunnels, and enlarged maternity chambers. Natal dens are used from year to year and may be altered or extended each year. Natal dens may represent ancestral breeding or rearing sites that are important to survival of the species. Because of the denning territoriality of the species, 1.2 - 2.0 miles usually separate active natal dens of different mated pairs. Thus, natal den density becomes a major limiting factor for a kit fox population (USFWS 1983, Morrell 1975, 1972).
Natal dens are found on terrain of limited slope, averaging about 6 degrees. About 50 percent are found on flat terrain. Active natal dens are more likely to have scats, prey remains, and extensive matted vegetation around their entrances. Tunnel size varies from 5-6 inches high and 6-8 inches wide. Maternity chambers may be as large as 24 inches wide and 12 inches high. Tunnels and maternity chambers may extend as far as 50 inches below the ground surface. Because a family may move from one den to another during the reproductive period, there are usually several natal dens within a denning territory. Den changes may be due to depleted prey base or ectoparasite infestations (USFWS 1983, O’Farrell and McCue 1981).
Female San Joaquin kit foxes return to natal dens in September or October and begin to clean and enlarge them. The males join the females in October and November. Breeding begins in December and extends into January or February. Young are born in February or March following a 49-55 day gestation period. The females have only one litter 3-5 pups per year, averaging 3.4. Pups do not emerge from the den until they are about one month old. They are probably weaned at about that time. Individual foxes do not breed successfully their first year, maturing at 22 months of age or later. They are basically not monogamous even though the prior mates may co-inhabit an area. Occasionally there may be a pair that mates year after year. Males rarely fight over a female and may breed with several females (USFWS 1983, Morrell 1975, 1972).
The female nurses the pups for about 1 to 2 months. Both parents forage for food for the young and bring captured prey animals to the den for the pups until they are about 4-5 months old. At that time the pups begin to forage for themselves, family bonds begin to dissolve, and individuals disperse. During the period when adults are providing food for the young, the male may occupy the same den with the female or will use another den nearby. Sometimes after a family separates, a pup may stay with an adult or another pup through the summer (USFWS 1983, Morrell 1975, 1972).
San Joaquin kit fox abundance depends directly in the number of natal den sites available and the abundance of prey animals. Territoriality of denning pairs limits the number of natal dens per unit area. Home range area for individual foxes depends on adequate prey base and can overlap extensively with other foxes. Early estimates indicated densities of 1.0 adult kit fox per square mile. In 1970, it was estimated at 0.36 to 1.0 per square mile. A more refined study in 1975 based on density of active dens indicated between 1.0 and 1.4 kit fox per square mile. Valley floor habitats generally have higher kit fox densities than foothill areas. An analysis of available data in 1983 indicated that there were about 7,000 kit foxes occupying about 5,000 square miles of habitat in 1975. There has subsequently been more San Joaquin Valley floor habitat lost to agricultural and other developments. This amounted to about 60 square miles annually during the period 1976 to 1979 (USFWS 1983, 1985, Morrell 1975, 1972, Jensen 1972).
Estimates of the size of the range occupied by the kit fox have changed over the years. It has apparently been severely reduced from the original range within the San Joaquin Valley and Carrizo Plain. Subsequent studies in 1970 and 1975, however, indicated expansion of kit fox range into portions of the southern San Joaquin Valley and Coast Range foothills and additional intermountain plains. It is not known if this condition reflected recent colonization into these areas or if earlier studies were not thorough enough to detect kit fox locally (Morrell 1975, 1972).
Population densities are typically relatively stable; where others moving in replace individuals leaving an area. Young individuals are only able to establish themselves if an adult moves out, dies or is killed. Spotlighting surveys of selected portions of the range indicated an overall increase between 1970 and 1975 with a slump in 1972. Starvation will eliminate surplus kit foxes in the absence of other mortality factors. They can live to at least seven years of age; however, longevity averages between 1.8 and 2.2 years. In that time a pair of foxes can produce two litters of 3 to 5 pups (Morrell 1975, 1972).
Changes in prey base abundance can influence kit fox densities and could reduce their populations if widespread or long-term trends of prey base reduction took place. Loss of habitat remains the greatest threat to this taxon.
San Joaquin kit fox are preyed upon by badgers (Taxidea taxus), coyote (Canis latrans), and probably golden eagles (Aquila chrysaetos) (Grinnell et al. 1937, Morrell 1975, 1972). Prey species for kit fox are given above under “Food Habits”.
Parasites of kit fox include sticktight fleas (Echionorhoya gallinacea) and other fleas, ticks, lice, and possibly roundworms and tapeworms.
Other animals common to kit fox habitat include: skunks (Spilogale putorius, Mephitis mephitis), burrowing owls (Athene cunicularius), lesser nighthawks (Chordeiles acutipennis), western kingbirds (Tyrannus verticalis) and many other bird species, blunt-nosed leopard lizards (Gambelia silus), western whiptail lizards (Cnemidophorus tigris), side-blotched lizard (Uta stansburiana), coast horned lizards (Phrynosoma coronatum), coach whip snakes (Masticophis flagellum), gopher snakes (Pituophis melanoleucus), western rattlesnakes (Crotalus viridis) and many insects and spiders (McGrew 1979, USFWS 1983, 1985, Morrell 1975, 1972, O’Farrell 1980, Clark et al. 1982).
The primary threat to the San Joaquin kit fox is the loss of habitat in the San Joaquin Valley due to agricultural development. Conversion of native lands to agriculture has been greatly accelerated by the development of the Federal Central Valley Project and the California Water Plan, along with numerous other local water developments. Off-site reservoirs and conveyance facilities have provided abundant inexpensive water for irrigation. Diversions, canals, and water storage ponding (flooding) within the kit fox range have contributed to habitat loss (USFWS 1983, Morrell 1975, 1972). Agricultural development related losses include: direct mortality from burial in dens by heavy equipment operation; displacement of kit foxes from their home ranges; a displaced or reduced prey base requiring increased foraging area for kit foxes (this increase mortality from road-kills because of an increase in roads and traffic); and reduced kit fox reproduction resulting from destroyed denning areas (Morrell 1975). Other, less extensive habitat losses in the San Joaquin Valley area result from urbanization, industrial development (particularly oilfields), and construction projects such as the California Aqueduct and Interstate Highway 5 (Laughrin 1970, USFWS 1983, 1985, Morrell 1975, 1972, Laughrin 1970, Jensen 1972). Each of these activities requires the operation of heavy equipment and alters the native landforms and vegetation. The results are the same as with agricultural development. In addition, oilfield operations can produce oil spills, which can kill or injure foxes and reduce their prey food base. Conversion of wildlands was largely responsible for the 20-43 percent reduction in kit fox population estimates during the 50 years prior to 1975 (Morrell 1975). An estimated 34 percent reduction in native habitat within the San Joaquin kit fox range took place between 1959 and 1969 (Laughrin 1970). By 1979, only 6.7 percent remained of the original 7,500,000 acres of undeveloped wildlands in the San Joaquin Valley south of Stanislaus County. At the current rate of habitat loss, it is estimated that there will be none left in that area by 1996 (USFWS 1985).
Other threats include shooting, trapping, road-kills by motor vehicles, off-road vehicle activity, pesticides, (for animal damage control activities) and domestic livestock grazing (Morrell 1975, Swick 1973, USEPA 1983).
Illegal shooting of kit foxes was considered a significant problem and resulted in the closure of certain portions of its range to night hunting in 1972. Some illegal shooting continues, however. Along with illegal shooting, direct mortality to kit foxes occurred during past fur-trapping activities. In 1972, trapping was made illegal in portions of the kit fox range. In 1981, the closure was modified to allow trapping of legal non-game mammals. The extent to which kit foxes are taken incidentally to this is not known (USFWS 1983, Morrell 1975, 1972). Road kills have increased as roads and highways have been developed and vehicle traffic has increased along existing roads. Off-road vehicle activity can contribute to habitat damage by destroying vegetation, compacting soils and accelerating erosion. Declines in kit fox populations in the Panoche Hills of Fresno County were linked in part to excessive habitat destruction associated with off-road vehicles. A study of desert kit fox failed to show impacts from off-road vehicle activities; however, it was concluded that denning areas, especially natal and pupping, should be protected from off-road vehicle harassment and possible collapse of dens (Morrell 1975, Jensen 1972, O’Farrell and Gilbertson 1979). This type of activity will continue to effect San Joaquin kit fox habitats and will probably be intensified locally as sites available for off-road vehicle recreation are reduced by other land uses. Concerns about pesticides used in rodent control and their effects on San Joaquin kit fox have been expressed for many years. Laboratory studies indicate that kit foxes are very sensitive to rodent bait containing compound 1080 (sodium monofluoroacetate). Because kit foxes are known to feed on carrion, they may consume poisoned animals or feed them to their young. Studies by the U.S. Environmental Protection Agency, using the desert kit fox (V. m. arsipis) as a test animal, clearly show a high vulnerability to kit foxes through ingestion of poisoned rodents. Additionally, a study using radio-collared coyotes showed that animals showing clear signs of 1080 poisoning died in areas where they could otherwise never have been found. The duration of time between ingestion of poisoned food and onset of poisoning symptoms (1-24 hours) provides ample time for animals to seek shelter underground in dens away from the 1080 application area (USEPA 1983, Hegdad et al. 1979). Agricultural interests maintain the necessity of applying toxic chemicals for rodent and lagomorph control (USFWS 1983, Morrell 1975, 1972, Jensen 1972, Swick 1973, USEPA 1983).
Grazing of domestic livestock has modified habitat in much of the kit fox range. The effects of livestock grazing on kit foxes are not well understood. Grazing may have been responsible for kit fox range extension into the Salinas and Santa Clara Valleys by modifying the habitats there. However, it is generally agreed that overgrazing is detrimental to kit foxes (McGrew 1979, USFWS 1983, Morrell 1975, 1972, Jensen 1972, Swick 1973).
U.S. Fish and Wildlife Service. 1985. Revised San Joaquin Kit Fox Recovery Plan. U.S. Fish and Wildlife Service, Portland, OR. 84 pp.
U.S. Fish and Wildlife Service. 1998. Recovery Plan for Upland Species of the San Joaquin Valley, California. U.S. Fish and Wildlife Service. Region 1. Portland, Oregon, USA.
The ultimate objective of the Recovery Plan is to delist the San Joaquin kit fox. However, at this time it is not known what population levels and degree of habitat protection are necessary to satisfy criteria for delisting. Appropriate research is proposed as a high priority task to provide this information. Interim objectives of halting the decline of the San Joaquin kit fox and then increasing population sizes above 1981 levels, thus justifying a change in status from Endangered to Threatened are proposed. To achieve the interim objectives, it is recommended that: (1) 35,000 acres of San Joaquin kit fox habitat be protected in Zone 1 (Zone 1 contains the focus of the remaining San Joaquin kit fox population located in western Kern and eastern San Luis Obispo Counties. It also contains a large contiguous parcel of relatively undisturbed but manageable Federal land in the Elk Hills and Buena Vista naval petroleum reserves, plus substantial acreage on adjacent BLM land. Heaviest demands on the remaining land are for petroleum developments and grazing.); (2) protection of the San Joaquin kit fox and its habitat in Zones 1, 2, and 3 be provided (Zone 2 includes the rest of Kern and San Luis Obispo Counties as well as Tulare, Kings, Fresno, Monterey and a small part of San Benito County that contain the remaining concentrations of San Joaquin kit fox. Zone 3 contains lower density populations of San Joaquin kit fox in a scattered distribution through the northern part of the range in Merced, Stanislaus, San Joaquin, Contra Costa, Alameda, Santa Clara, and San Benito Counties, as well as the Cuyama Valley in Santa Barbara County); and (3) that the fox be managed to provide at least 1.4 adult San Joaquin kit fox per square mile on privately-owned and public lands. The recovery activities necessary to achieve these interim criteria are to:
1. Reduce or reverse the rate at which habitat of the San Joaquin kit fox is being lost (to agriculture, road construction/maintenance, development, and related activities in and also to recreational off-road vehicles) by initiating a program of habitat management, protection, and acquisition. Strict land zoning may aid in protection of future habitat loss to development.
2. Acquire additional information necessary to understand the ecological life history requirements of the San Joaquin kit fox and to determine their compatibility with human activities such as petroleum field developments, grazing, rodent control programs, and agricultural development.
3. Restore degraded habitats by enhancing natural routes and rates of reclamation.
4. Monitor progress of recovery be determining changes in kit fox distribution and abundance, habitat losses or gains, rates of habitat restoration, and acquisition of new information about the kit fox.
5. Investigate the feasibility of reintroductions in portions of the original range of the San Joaquin kit fox that appear to be suitable essential habitat, but presently lack evidence of use by the species.
6. Develop strategies for integrating recovery plan objectives into development and management goals for the southern San Joaquin Valley.
7. Determine criteria necessary to justify delisting the species.
Christenson, D. P. 1984. Blunt-nosed leopard lizard habitat, evaluation of changes 1980-1983. Rept. to: U.S. Fish and Wildl. Serv., Contr. 11310-01687-3, U.S. Fish and Wildl. Serv., Sacramento, CA. 3 pp.
Clark, W.A., S.M. Juarez, and D.L. Chesemore. 1982. Nature Conservancy small mammal inventory of Paine Wildflower Preserve and The Voice of America in Kern County, California. Calif. State Univ., Fresno. 47 pp.
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