Vulpes macrotis mutica

Reduced, fragmented range in the San Joaquin Valley and adjacent areas in California, population size probably a few to several thousand individuals; declining due to habitat loss/degradation/fragmentation caused by human activities, interactions with coyotes and red foxes, poisoning efforts that have reduced prey populations, and other factors.

Range includes the San Joaquin Valley, California, encompassing portions of the valley floor and adjacent foothills and interior Coast Range valleys, historically from as far north as Tracy (San Joaquin County) and La Grange (Stanislaus County) and south to Kern County) (Grinnell et al. 1937, USFWS 2010). At one time, the range was believed to have decreased to only the southern and western parts of the San Joaquin Valley and adjacent foothills and interior Coast Range Valleys, but subsequent research found these foxes in many additional areas, northward to Contra Costa County, including areas where the species previously had not been detected (USFWS 2010). However, some recently documented locations likely reflect dispersing individuals rather than resident populations, and many populations are small, isolated, and/or declining or apparently extirpated (USFWS 2010).

This fox is represented by three core subpopulation units and several satellite subpopulations (USFWS 2010).

Decline is attributable to conversion of habitat to irrigated cropland; residential, water, and petroleum development, and poisoning programs that have reduced prey populations (Biosystems Analysis 1989, California DF&G 1990). Interactions with coyotes (predation, competition) can have a significant negative impact on populations (see USFWS 2010), and expanding populations of non-native red foxes may pose a threat in some areas (see USFWS 2010).

USFWS (2010) summarized threats to habitat as follows: Loss, modification, and fragmentation of habitat continue to be the primary threats. Most of the optimal habitat on the valley floor has been converted to agriculture. Although the rate of agricultural conversion on the valley floor has slowed in recent years, urban and agricultural conversion activities have continued to extend up to and into the lower foothill slopes where corridors of residual habitat had remained. In many areas, remaining natural lands have become fragmented, inhibiting movement of kit fox between remnant parcels and delaying or preventing recolonization of retired and restored habitat. Some isolated parcels, including protected lands, have lost the vegetative structure or prey species important to persistence of kit fox populations, resulting in loss of resident kit fox subpopulations. Restoration of the kit fox's natural habitat has proved difficult, and lands, such as retired lands that were thought to be valuable for kit fox recovery, do not necessarily provide adequate conditions for kit fox. In the Western Kern County and the Carrizo Plain core areas, where foxes remain relatively abundant, threats due to oil and gas leasing continue. USFWS and its public and private partners have made great progress in acquiring lands for conservation. Currently, land ownership or management for 60 percent of occurrences is unknown, 13 percent of occurrences are recorded from private lands, and roughly 24 percent of occurrences are recorded from various federal, state, regional, county, and city holdings that are subject to varying management goals and objectives. Kit foxes are mobile predators that require large home ranges, and appropriate vegetative, prey, and predator conditions to persist. Despite recent conservation efforts, kit fox subpopulations appear to be declining.

A number of large-scale solar development projects that would threaten kit fox population clusters are
currently proposed for construction in kit fox habitat (USFWS 2010).

Constriction of available habitat and occurrence of barriers such as the canals and several high-traffic roads potentially limit fox movements (see USFWS 2010).

USFWS (2010) summarized the threat from predation and disease as follows. Predation by large canid predators including the coyote and non-native red fox appears to be a major and increasing threat to the viability of kit fox populations. In most areas of the kit fox's range, coyotes are the primary cause of kit fox mortality, and survival rates of kit fox decrease significantly as coyote-caused mortality increases. Canid predators have increased both in distribution and abundance with the increased land conversion, presence of water sources, and related human activities in the San Joaquin Valley. Abundant coyote populations currently appear to be excluding kit fox from some protected kit fox habitat. Disease does not appear to be an important threat to the kit fox at this time.

USFWS (2010) summarized additional threats as follows. Newer formulations of rodenticides and pesticides subject kit foxes to direct and secondary poisoning, have been linked to kit fox mortality, and are used widely within the range of the kit fox. Although no research to date has quantified the effect of rodenticides on kit fox populations, USFWS expects that rodenticide exposure could have substantial population-level effects, especially where population are small and where kit fox rely on rodent species targeted by rodenticides. The effectiveness of new regulations on the use of rodenticides in preventing kit fox exposure in not currently known. Rodenticides and pesticides may also negatively effect kit fox populations through their reduction of the fox's rodent and insect prey resources. In addition, selenium toxicity may threaten kit fox in some areas on the western side of the San Joaquin Valley where elevated concentrations of selenium are present at the ground surface. Toxicity effects range from reduced appetite and subnormal growth to mortality. Additional threats include loss of individuals to mortality from accidental shooting, vehicle strikes, off-road vehicle use, and research-related activities. Where populations are small, such events could have population-level effects and could increase the threat of stochastic extinction. Where populations are small, inbreeding depression, genetic drift, and stochastic extinction are recognized threats. Climate change may threaten kit fox populations through increased variability in precipitation and severe weather events, which in turn are expected to reduce prey availability.