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NATURAL HISTORY

SAN JOAQUIN KIT FOX } Vulpes macrotis mutica
FAMILY: Canidae

DESCRIPTION: The San Joaquin kit fox is the smallest member of the dog family in North America, with an average body length of 20 inches, an average tail length of 12 inches, and a height of about nine to 12 inches at the shoulder. Adult males weigh about five pounds, while adult females weigh about 4.6 pounds. These slender mammals have relatively long legs and large ears.

HABITAT: This species historically inhabited grassland, scrubland, and wetland communities in the San Joaquin Valley and adjacent habitat. Today, the kit fox must often resort to living in and near agricultural and urban areas.

RANGE: This species is endemic to California and historically was found throughout the San Joaquin Valley and in adjacent foothills and grasslands. The largest remaining intact habitat is found in and near the Carrizo Plain National Monument in western Kern County and in and near Tejon Ranch in the far south of the valley.

MIGRATION: Development has significantly degraded movement and dispersal corridors for young kit foxes. Juvenile survival and successful dispersal has been declining in recent years. Thus, successful movement of kit foxes between remaining core habitat areas is becoming increasingly unlikely.

BREEDING: Kit foxes generally mate in winter and have one litter of two to six pups. Reproductive success has been shown to correlate with prey availability, and breeding success drops in years when prey is scarce.

LIFE CYCLE: The minimum breeding age for kit foxes is one year. Pups are born in February or early March, and after four to five months will start to forage by themselves and seek mates and vacant home ranges. Juvenile dispersal can be less than five miles or up to 60 miles from their natal dens (Thelander 1994). Kit foxes live for up to seven years in the wild, while captive animals can live up to 12 years.

FEEDING: The San Joaquin kit fox is a small mammalian carnivore and a nocturnal predator that feeds largely upon rodents and rabbits — particularly black-tailed jackrabbits and desert cottontails — as well as insects, reptiles, some birds, bird eggs, and rarely some vegetation. Kit foxes can go for days without water if they have adequate prey.

POPULATION TREND: The San Joaquin kit fox is declining. Due to large fluctuations in annual precipitation and prey availability, sizeable fluctuations in kit fox numbers may be natural for kit foxes living in a desert ecosystem — but even accounting for such annual fluctuations, the overall population had significantly declined by the time of Endangered Species Act listing and continues to do so.

Photo courtesy USFWS