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Island Fox

dnaoodb: professional biology database , biology encyclopedia

in biology, Island Fox (Alias:Urocyon Littoralis or Channel Islands Fox) is a small fox species that is endemic 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 Fox has a body length of 48-50 cm, a shoulder height of 12-15 cm, and a weight of 1.3-2.8 kg. Living on six islands in California's Channel Islands. It is the smallest fox in the United States and has six subspecies. Each subspecies lives on an island. For example, the Santa Cruz Island Fox lives on Santa Cruz Island. In Channel Islands National Park, there are Island Fox on these six islands: San Miguel Island, Santa Rosa Island, Santa Cruz Island, Santa Carolina Island, San Nicolas Island, and San Clemente Island. Among them, Santa Cruz Island is the best spot to watch Island Fox. There are more than 1,000 Island Fox here, which often appear in Scorpio Ranch Camp.

Because Island Fox lives on an island, they have no resistance to parasites from the mainland, especially dog germs. In addition, predation by golden eagles and human activities have drastically reduced the number of Island Fox. In 2004, the U.S. Federal Fish and Game Service (USFWS) listed four subspecies as endangered and protected the island's environment.

Scientific classification

Island Fox,Urocyon Littoralis,Channel Islands Fox
Protection level:
Named by and Year:
Baird, 1857
Subphylum Vertebrata
Class Mammalia
Island Fox
Mode Of Reproduction:
Reproductive Form:
Sexual Reproduction


The island fox is significantly smaller than the related gray fox, and is the smallest fox in North America, averaging slightly smaller than the swift (Vulpes velox) and kit foxes (Vulpes macrotis). 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 species exhibits sexual dimorphism: 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. The island fox molts once a year between August and November. Before the first molt pups are woolly and have a generally darker coat than adult foxes. A brown phase, with the grey and black fur of the body replaced by a sandy brown and a deeper brown, may occur in the San Clemente Island and San Nicolas Island populations. It is unclear if this is a true color phase, a change that occurs with age, or possibly a change that occurs because of interactions with Opuntia cactus spines that become embedded in the pelt.

History Of Species

The most cunning animal in the Channel Islands of California, USA, is the Island Fox, a species endemic to the Channel Islands. The Island Fox has gray and red embroidered fur and is a descendant of the mainland gray fox, but it is much smaller than the mainland gray fox and is about the same size as an ordinary house cat. Island Fox lives on six of the eight islands in the Channel Islands, and the Island Fox on each island belongs to a different subspecies. Each subspecies has subtle differences, such as some having shorter tails and some having longer noses, reflecting their different evolutionary evolutions.

Island Fox's small size allows them to adapt to the island's resource-poor environment. They are thought to have crossed the sea to the northern islands between 10,400 and 16,000 years ago. Originally, they lived on the three northernmost islands. These islands were easier to access during the last ice age. When the sea level dropped, the four northernmost islands were combined into a large island (Santa Rosae), and the distance between this island and the mainland also became shorter. It is possible that Native Americans brought them to the southern islands as pets or hunting dogs.

Island Fox captures rats at night for food. According to the limited fossil record and their genetic distance from the ancestors of gray foxes, the gray foxes of the northern islands are the oldest subspecies. The San Clemente Island Fox has only lived on the island for about 3,400-4,300 years, while the San Nicolas Island Fox has only lived on the island for about 3,400-4,300 years. Fox became an independent group 2,200 years ago. The Island Fox does not survive on Anacapa Island because there is no fresh water supply on the island. Tababa Island is too small to provide enough food.


Island Fox inhabits woody undergrowth. They live in island biomes, including temperate forests and rainforests, temperate grasslands and jungles, and no island has more than 1,000 Island Foxes.

Living Habits

Island Fox is not afraid of humans. It is at the top of the food chain on the island and has no natural predators. Generally very docile and easily tamed. They communicate with each other using signals such as smell, hearing and vision. The Island Fox will vocalize, stare, and tilt its ears to make other gray foxes obey. They use urine and feces to identify their territory.

They are omnivores and eat fruits, insects, birds, eggs, crabs, lizards and small mammals, including deer mice. They usually appear alone, are usually active during the day, and appear at dawn or dusk. Seasons also affect their activity, with them being more active in summer than in winter.

Distribution Area

Island Fox lives on six islands in the Channel Islands of California, USA. San Miguel Island, Santa Rosa Island, Santa Cruz Island, Santa Carolina Island, San Nicolas Island, San Clemente Island. The three largest islands, Santa Cruz, Santa Rosa, and San Miguel, are managed by Channel Islands National Park; the other two islands, San Nicolas and San Clemente, are managed by the U.S. Department of the Navy; Catalina Island is managed and owned by the Catalina Island Water Conservancy.

Reproduction Method

Island Fox are generally monogamous and enter their breeding season in January each year (which lasts until late February or early March). During the breeding season, males and females often appear together. The gestation period is about 33-50 days. They give birth in caves and can give birth to 5 fox cubs in one litter, with an average of 2 or 3. Fox cubs are born in the spring and can leave the burrow in early summer. A mother fox will nurse her young for 7-9 weeks. It takes 10 months for fox cubs to reach sexual maturity, and female foxes usually give birth within the first year. The lifespan of a wild Island Fox is about 4-6 years, while the lifespan of a captive Island Fox can be up to 8 years.

Population Status

Island Fox populations experienced a catastrophic decline in the 1990s. Animal conservation experts discovered the Island Fox's population was declining in the 1990s. On São Miguel Island, the Island Fox began to decline in 1994, and the adult population dropped from 450 to 15 in 1999. Similar declines were noted on Santa Cruz Island, where the number of adult Island Foxes dropped from 2,000 in 1994 to 135 in 2000; and on Santa Rosa Island, the number dropped from 1,500 in 1994 to 14 in 2000.

Using radio collars to monitor the Island Fox, it was discovered that it was hunted by golden eagles, resulting in a significant decline in the population. Golden eagles were not seen in the Channel Islands until the 1990s, and the first golden eagle nest was discovered on Santa Cruz Island in 1999. Biologists believe that the golden eagles were attracted to the growing number of wild livestock (such as pigs) on the island. In addition, the bald eagles (which feed on fish) that hindered the golden eagles from settling on the island were also exposed to DDT in the 1950s. After being killed, golden eagles proliferated on the island. The number of golden eagles on the island was four times that of Island Fox. In addition, in the North Channel Islands, the replacement of the historic dominant vegetation of shrubs with non-native grassland due to sheep grazing has altered the environment that originally provided cover for gray foxes from aerial predators, resulting in the loss of gray foxes. Fox numbers are declining.

Because Island Fox lives in an isolated environment, they lack immunity against parasites and diseases brought by mainland dogs. In 1998, canine distemper occurred on Santa Catalina Island, killing nearly 90% of the Island Fox population. Species introduced from other places, such as cats, pigs, sheep, goats and American bison (introduced to Santa Catalina in the 1920s by Hollywood film crews making western films), have reduced the island's food supply and damaged the environment. The decline in quality has a negative impact on the quantity of Island Fox. Island Fox poses a threat to the endangered Silky Shrike on San Clemente Island. The U.S. Navy's large-scale hunting of Island Fox on the island has also reduced their numbers. Until 2000, the U.S. Navy used different strategies, including capturing Island Fox during the breeding period of the shrike, installing an electric grid in the shrike's living range, and using electric shock collars. There are also many Island Foxes who have been hit and killed by cars on San Clemente Island, San Nicolas Island and Santa Caterina Island.

The way to successfully protect Island Fox is to remove golden eagles from the Channel Islands, restore the ecosystem, and control disease. To ensure the survival of the Island Fox, golden eagles are now moving from the northern islands to the mainland. Maintaining and increasing bald eagle populations could help replace golden eagles. Livestock are being removed from Santa Catalina and Santa Cruz Islands to remove food for the golden eagles and competition for the Island Fox. To reduce the risk of disease, pets are not allowed in Channel Islands National Park. A vaccination program against canine distemper is also underway on Santa Caterina Island. Because the Channel Islands are basically owned and controlled by the Santa Catalina Island Conservation Commission or the U.S. government, Island Fox can be protected and monitored without human infringement.

In 2004, the U.S. Fish and Game Service (USFWS) listed four Island Fox subspecies in the archipelago as endangered species. In the United States, the California Department of Fish and Game listed all six subspecies as vulnerable in 1987. Captive breeding programs combined with other measures have saved the species from extinction, and as of 2013, the Island Fox's population is relatively stable.