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Island Fox
Urocyon littoralis pair.jpg
Conservation status
Scientific classification
Kingdom:
Phylum:
Class:
Order:
Family:
Genus:
Urocyon
Species:
U. littoralis
Binomial name
Urocyon littoralis
(Baird, 1857)
Subspecies of island fox.png
Range map

The island fox (Urocyon littoralis) is a small fox that is native to six of the eight Channel Islands of California. There are six subspecies, each unique to the island it lives on, reflecting its evolutionary history.

Island foxes are generally docile, show little fear of humans, and are easily tamed.

Island foxes played an important role in the spiritual lives of native Channel Islanders. Island foxes have been likely semi-domesticated as pets, used as pelts, or for other functions, like pest control.

Taxonomy and evolution

Skull of an island fox (right) compared with that of a gray fox (left)
The skull of an island fox (right) compared with a skull of the related gray fox (left).

The island fox shares the genus Urocyon with the mainland gray fox, the species from which it is descended. Its small size is a result of insular dwarfism.

There are six subspecies of the island fox, each of which is native to a specific Channel Island, and which evolved there independently of the others. The subspecies are:

Foxes from each island are capable of interbreeding, but have genetic and phenotypic distinctions that make them unique; for example, the subspecies have differing numbers of tail vertebrae.

The small size of the island fox is an adaptation to the limited resources available in the island environment. The foxes are believed to have "rafted" to the northern islands between 10,400 and 16,000 years ago. Initially, fox populations were located on the three northern islands, which were likely easier to access during the last ice age — when lowered sea levels united four of the northernmost islands into a single mega-island (Santa Rosae) and the distance between the islands and the mainland was reduced — it is likely that Native Americans brought the foxes to the southern islands of the archipelago, perhaps as pets, or hunting dogs.

Vulpes littoralis
Engraving of the island fox from the Pacific Railroad survey of 1855

Other names for the island fox include coast fox, short-tailed fox, island gray fox, Channel Islands fox, Channel Islands gray fox, California Channel Islands fox and insular gray fox.

Description

The island fox is significantly smaller than the gray fox and is the smallest fox in North America, averaging slightly smaller than the swift and kit foxes. Typically, the head-and-body length is 48–50 cm (19–19.5 in), shoulder height 12–15 cm (4.5–6 in), and the tail is 11–29 cm (4.5–11.5 in) long, which is notably shorter than the 27–44 cm (10.5–17.5 in) tail of the gray fox. This is due to the fact that the island fox generally has two fewer tail vertebrae than the gray fox. The island fox weighs between 1 and 2.8 kg (2.2 and 6.2 lb). The male is always larger than the female. The largest of the subspecies occurs on Santa Catalina Island and the smallest on Santa Cruz Island.

The island fox has gray fur on its head, a ruddy red coloring on its sides, white fur on its belly, throat and the lower half of its face, and a black stripe on the dorsal surface of its tail. In general the coat is darker and duller hued than that of the gray fox.

Reproduction

Urocyon littoralis pup
An island fox kit nestled in the brush

The island fox typically forms monogamous breeding pairs, which are frequently seen together beginning in January and through the breeding season, from late February to early March. The gestation period is 50–63 days.

The female island fox gives birth in a den, a typical litter having one to five pups, with an average of two or three. Pups are born in the spring and emerge from the den in early summer; the mother lactates for 7–9 weeks.

Sexual maturity is reached at 10 months, and the females usually breed within the first year.

Island foxes live for 4–6 years in the wild and for up to 8 years in captivity.

Ecology and behavior

Urocyon littoralis with prey*corrected*
A nighttime shot of an island fox with prey in its jaws.

Its preferred habitat is complex layer vegetation with a high density of woody, perennially fruiting shrubs. The fox lives in all of the island biomes including temperate forest, temperate grassland and chaparral, with no island supporting more than 1,000 foxes.

The fox tends to move around by itself, rather than in packs. It is generally nocturnal, although with peaks of activity at dawn and dusk. Activity also fluctuates with the season: It is more active during the day in summer than it is in winter.

The island fox is not intimidated by humans, although at first may show aggression. It is quite easy to tame and is generally docile.

The island fox communicates using auditory, olfactory and visual signals. A dominant fox uses vocalizations, staring, and ear flattening to cause another fox to submit. Signs of dominance and submission are visual, such as facial expression and body posture. Its main vocalizations are barking and growling. The island fox marks territory with urine and feces.

Diet

The island fox eats fruits, insects, birds, eggs, crabs, lizards, and small mammals, including deer mice.

Conservation status and Federal Protection

GoldenEagle-Nova
The golden eagle is four times the size of the island fox and can easily prey on it.
San Clemente Island Fox (Urocyon littoralis clementae) at Santa Barbara Zoo 2016-01-27
San Clemente Island Fox at Santa Barbara Zoo as part of a Species Survival Plan

Because the island fox is geographically isolated, it has no immunity to parasites and diseases brought in from the mainland and is especially vulnerable to those that the domestic dog may carry. In addition, predation by the golden eagle and human activities devastated fox numbers on several of the Channel Islands in the 1990s.

Four island fox subspecies were federally protected as an endangered species in 2004, and efforts to rebuild fox populations and restore the ecosystems of the Channel Islands are being undertaken. Radio collars are being attached to foxes in an effort to track and locate the young foxes. To date these efforts have been largely successful.

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