Urocyon littoralis, the island grey fox, can be found on the six largest Channel islands, about 30 to 98 kilometers off of the southern California coast in North America. These islands are Santa Catalina, San Clemente, San Nicholas, San Miguel, Santa Cruz, and Santa Rosa Islands.

(Claybourne & Collins 1995, Wayne et al. 1991, Chapman 1999, Schmeckpepper 1999)

Biogeographic Regions: nearctic (Native )

Other Geographic Terms: island endemic

endemic to a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (250-1000 square km (about 100-400 square miles)) The range includes six islands off the southern California coast: Santa Catalina, Santa Cruz, Santa Rosa, San Miguel, San Nicolas, and San Clemente (Roemer et al. 2004); these are the six largest of the eight Channel Islands. Archeological and geological evidence suggests that foxes arrived on the three northern islands minimally 10,400-16,000 years ago and dispersed to the three southern islands 2200-4300 years ago (Wayne et al. 1991), or Native Americans may have translocated foxes from the northern islands to the southern islands (Moore and Collins 1995). Genetic data indicate that all island foxes are descended from one colonization event (see Moore and Collins 1995). Extent of occurrence is not more than several hundred square kilometers.

Island grey foxes resemble dwarf versions of the grey fox (Urocyon cinereoargenteus). This is the smallest fox species known from the United States. Adult males weigh 2.00 kilograms on average, while adult females weigh 1.88 kilograms. Body length, including head and tail, ranges from 59 to 79 centimeters. Tail length alone ranges from 11 to 29 centimeters. Height at the shoulder is from 12 to 15 centimeters.

Fur is greyish-white and black with cinnamon underfur on the dorsal side, and with pale white, yellow, and rusty-brown on the ventral surface. The chin, lips, nose, and areas around the eyes are lined in black while the sides of the rostrum are grey. The ears, neck, and sides of the limbs are cinnamon-colored. The tail has a contrasting thin black stripe on the dorsal side with a mane of stiff hairs. The underside of the tail is a rusty color. Fur color may differ among islands and be highly variable among individuals, ranging from overall greyish to honey brown and red. Island grey foxes molt once a year during the fall months from August to November. At that time, the fur coat fades in color and the fur tips curl at the ends.

Young foxes tend to have a paler but thicker dorsal fur coat compared to adults. In addition, the ears are darker in color compared to adult foxes.

(Claybourne & Collins 1995, Crooks 1994, Chapman 1999, Schmeckpepper 1999, Weston date unknown, Fritzell et al. 1999)

Range mass: 1 to 2 kg.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Differs from U. CINEREOARGENTEUS primarily in smaller size (e.g., tail length 110-290 mm vs. 275-445 mm; usually more than 300 mm in CINEREOARGENTEUS) and somwhat darker overall coloration (Moore and Collins 1995).

• Terrestrial

Channel island foxes can be found in all types on habitats of the Channel islands. This includes valley and foothill grasslands, coastal sage/scrub, coastal bluff, sand dune areas, island chapparral, southern coastal oak woodland, island woodland, southern riparian woodland, pine forests, and coastal marshes.

(Claybourne & Collins 1995, Fritzell et al. 1999)

Terrestrial Biomes: savanna or grassland ; chaparral ; forest

Comments: This fox occurs in all habitat types on the islands, but it is most abundant in woodland and chaparral, especially where there is a middle shrub layer. It takes shelter in thick vegetation, holes in the ground, brush piles, rock piles, and hollow trees; does not excavate its own burrow (Biosystems Analysis 1989).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Island grey foxes are omnivorous, with a diet consisting mostly of insects and fruits. Their diet depends on seasonal and regional abundance of food items. Fruits and berries include manzanita, toyon, saltbush, prickly pear cactus, ice plant, and the fruits of sea-figs. They also feed on deer mice and birds. Sometimes these foxes feed on reptiles such as lizards, amphibians, land snails, and human refuse, but not as frequently since these items are not as abundant on the islands. In addition, they are known to scavenge for food on beaches along the coastline.

(Claybourne & Collins 1995, Garcelon et al. 1999, Chapman 1999, Schmeckpepper 1999, Weston date unknown)

Animal Foods: birds; mammals; amphibians; reptiles; insects; mollusks

Plant Foods: fruit

Primary Diet: omnivore

Comments: Generally omnivorous. One study found scat to contain mammal remains 32% of the time, insect (beetles, grasshoppers, and Jerusalem crickets) 90% of the time, and plant material about 50% of the time. According to California Department of Fish and Game (1990), insects (particularly grasshoppers, crickets, and beetles) and fruits are the most important foods; also consumes birds and their eggs, mammals, and grasses.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 1 - 5

Comments: This species is represented by six island populations.

1000 - 2500 individuals

Comments: Population size was estimated to be approximately 1,660 in 2001 (T. Coonan, pers. comm., in USFWS 2001), 1,219-1,538 in 2002 (Roemer et al. 2004). Population estimates for each island as of 2002 are as follows: Santa Catalina: 224; Santa Cruz: 77-97; Santa Rosa (45); San Miguel: 28; San Nicolas: 435-734; San Clemente: 410 (Roemer et al. 2004).

On some islands, exists at higher densities than fox populations on the mainland; in the 1970s, estimated density in trapped habitats varied from 20.4 per square mile on Santa Cruz to 0.8 per square mile on Santa Catalina (Laughrin 1980). On Santa Cruz Island, mean home range size was about 24-35 ha (core area 4-7 ha), varying insignificantly with sex and season (Crooks and Van Vuren 1996).

Competition with feral cats or habitat degradation by introduced livestock may account for low density on some islands.

Comments: Primarily nocturnal, though not infrequently observed during daylight hours.

Since there is little sexual dimorphism and relatively equal sex ratios in population, it is suggested that this species forms monogamous bonds.

Mating System: monogamous

Mating season of island grey foxes occurs from January to April, depending on latitude.

After mating, female foxes give birth to a litter of kits in 50 to 63 days. Although average litter size is 2 to 3 kits, it can range from 1 to 5 kits.

These kits are born in dens. Dens include ground holes, hollow trees, rock piles, shrubs, caves, and man-made structures. These dens are usually found, not made by the fox. However, if the fox is unable to find an appropriate den, she will dig a hole in the ground. The den serves to protect the kits from harsh weather, predators, and other dangers.

Kits are born blind, weighing approximately 100 grams. They reach adult weight by their first winter. They depend on their mother for milk during the first 7 to 9 weeks. Around May to June, after being weaned, they emerge from their dens and forage for food with their parents. Both parents take care of the kits. An interesting observation is that when both parents and kits are caught in traps while foraging, the parents still care for the kits and provide food to them.

Fox kits remain with their parents during the summer but become independent by September. Young foxes usually stay around the den area while the parents disperse from it. They reach sexual maturity at about 10 months old. Island foxes are able to breed after one year of age.

(Claybourne & Collins 1995, Crooks 1994, Crooks & Van Vuren 1996, Garcelon et al. 1999, Nowak 1999, Chapman 1999, Schmeckpepper 1999, Weston date unknown, Fritzell et al. 1999)

Range number of offspring: 1 to 5.

Average number of offspring: 2.5.

Range gestation period: 50 to 63 days.

Average number of offspring: 2.6.

Average age at sexual or reproductive maturity (female)

Sex: female: 365 days.

Parental Investment: altricial ; extended period of juvenile learning

Breeds in February-early March. Young are born from late April through May after a 50-day gestation period. Adult females produce one litter of 1-5 (usually 2) young per year. Young remain with parents until August or September (Biosystems Analysis 1989). Spatial relationships among males and females suggest monogamy (Crooks and Van Vuren 1996).

• 2004
  Critically Endangered
• 1996
  Lower Risk/conservation dependent
• 1994
  Rare
  (Groombridge 1994)
• 1990
  Rare
  (IUCN 1990)

Urocyon littoralis is classified as "rare/lower risk" by the IUCN and "threatened" by the State of California and is protected by the California state law. There are no more than 1,000 foxes on each island and as few as 40 foxes on the smaller islands. Since their genetic variation is low, they are susceptible to disease and the consequences of environmental changes caused by man.

In 1993, their population was monitored by park biologists on San Miguel Island. This research revealed that this population of island foxes dropped from 450 in 1994 to less than 40 today. Similar outcomes are shown on the other islands. Populations on some islands have dropped as much as 90% in the past four years. This has sparked the park biologists to start a conservation team consisting of island fox researchers, captive breeding experts, canid genetics, wildlife disease experts, veterinarians, other canid biologists, and golden eagle researchers.

Threats to the island fox include loss of habitat, habitat changes resulting from the introduction of new herbivores, competition with feral cats, diseases brought by domestic dogs, and car accidents.

Measures and programs taken into effect to protect the island fox include disease investigations, elimination of feral cats, and potential captive breeding programs. The U.S. Navy and U.S. Park Service occupy their islands in order to help protect them. This species is currently a candidate for the U.S. ESA to be classified as threatened or endangered. It is already considered endangered by the State of California. Enforcing such protection is difficult, however, because they live on small remote islands.

(Nowak 1999, Chapman 1999, Schmeckpepper 1999, Weston date unknown, Fritzell et al. 1999, IUCN 1999, Wilson and Reeder 1993, National Park Service 1999)

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: critically endangered

United States

Rounded National Status Rank: N1 - Critically Imperiled

Rounded Global Status Rank: G1 - Critically Imperiled

Reasons: Restricted to the California Channel Islands (six islands); population size is less than 1,500; recent declines have occurred on five of the six islands; predation and disease are primary threats.

Global Short Term Trend: Decline of 50-70%

Comments: Since 1995, populations on Santa Cruz, Santa Rosa, San Miguel, and Santa Catalina islands have dramatically declined; the Santa Cruz island population decreased from 1,300 to fewer than 100 individuals (2002 Endangered Species Bulletin 27(3):29). A 40-60 percent decline in fox abundance on San Clemente Island occurred between the late 1980s and late 1990s (Roemer and Wayne 2003).

Four of the six island populations experienced precipitous declines in the late 1990s and early 2000s (Roemer et al. 2004).

Global Long Term Trend: Increase of 10-25% to decline of 30%

Comments: Trapping data for San Nicolas Island suggest a decline in the 1970s, during which time there was an increase in the feral cat population (Laughlin 1980). In the 1980s, population may have been stable on San Miguel, Santa Rosa, Santa Cruz, and San Nicolas islands; the population on Santa Catalina Island almost certainly declined, whereas status on San Clemente Island was unknown (California Department of Fish and Game 1990).

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Current primary threats incude predation by golden eagles on the northern Channel Islands and the possible introduction of canine diseases to all populations (Roemer et al. 2004). Canine distemper recently caused a large decline in the Santa Catalina population (Roemer et al. 2004). Recovery actions for the San Clemente loggerhead shrike, including a predator control program that involved euthanasia and confinement of foxes, likely contributed to the recent decline of foxes on San Clemente Island (Roemer and Wayne 2003). All populations are relatively small and vulnerable to demographic stochasticity and environmental extremes (Roemer et al. 2004).

Biological Research Needs: See Roemer et al. (2004) for a review of recent and current research.

Global Protection: Few (1-3) occurrences appropriately protected and managed

Comments: San Miguel, Santa Rosa, and Santa Cruz islands are included in the Channel Islands National Park. About two-thirds of Santa Cruz Island is owned by The Nature Conservancy and co-managed with the National Park Service. Approximately 87% of Santa Catalina Island is owned by the Santa Catalina Conservancy (a nonprofit conservation organization). San Clemente and San Nicolas islands are owned and managed by the U.S. Navy. Take, sell, and possession are prohibited by California law.

Native Americans used the Channel island fox for many purposes. Their fur was used for arrow-quivers, capes, blankets, and headdresses for ceremonial dances. Since they are docile in nature, they were also kept as pets. Native Americans used the island fox in their religious and ceremonial practices. They served as totems, dream-helpers, and legendary characters. Native Americans also had burials for these foxes, suggesting they were of religious importance.

Today, Urocyon littoralis are sometimes hunted.

(Collins 1991, Nowak 1999)

Stewardship Overview: See Roemer et al. (2004) for a list of recommended conservation measures, which include removal of golden eagles and reestablishment of bald eagles in the northern Channel Islands; removal of feral pigs from Santa Cruz Island; elimination of canine distemper as a mortality factor on Santa Catalina Island; public education; captive breeding and supplementation of wild populations with captive-reared foxes; population monitoring; and halt of management activities that are detrimental to island foxes (particularly those associated with San Clemente loggerhead shrike).

Comments: Each of the islands has been regarded as having its own endemic subspecies. Genetic distances among the island populations, as estimated by morphometrics, allozyme electrophoresis, mtDNA restriction-site analysis, and analysis of hypervariable minisatellite DNA, are not well correlated; there are no distinct trends of genetic variability with founding time (Wayne et al. 1991). This species has been regarded as possibly conspecific with U. cinereoargenteus by some authors, but it was recognized as a separate species by Jones et al. (1992) and Wozencraft (in Wilson and Reeder 2005). It has been placed in the genus Canis or the genus Vulpes by some authors (as recently as the 1970s).