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Island Fox

2007 Schools Wikipedia Selection. Related subjects: Mammals

                   iIsland Fox

                             Conservation status

   Critically endangered (CR)
            Scientific classification

   Kingdom: Animalia
   Phylum:  Chordata
   Class:   Mammalia
   Order:   Carnivora
   Family:  Canidae
   Genus:   Urocyon
   Species: U. littoralis

                                Binomial name

   Urocyon littoralis
   ( Baird, 1857)

   The Island Fox (Urocyon littoralis) is a small fox that is native to
   six of the eight Channel Islands of California. It is the smallest fox
   species in the United States. There are six subspecies of the fox, each
   unique to the island it inhabits, reflecting its evolutionary history.
   Other names for the Island Fox include Coast Fox, Short-Tailed Fox,
   Island Gray Fox, Channel Islands Fox, Channel Islands Gray Fox,
   California Channel Island Fox and Insular Gray Fox.

   The Island Fox shares the Urocyon genus with the mainland Gray Fox, the
   fox from which it is descended. Its small size is a result of island
   dwarfing, a kind of allopatric speciation. Because Island Foxes are
   geographically isolated they have no immunity to parasites and diseases
   brought in from the mainland and are especially vulnerable to those
   domestic dogs may carry. In addition, Golden Eagle predation 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.

Taxonomy and evolution

   The Island Fox shares the Urocyon genus with the mainland Gray Fox
   (Urocyon cinereoargenteus), the fox from which it is descended. Its
   small size is a result of island dwarfing, a kind of allopatric
   speciation (that is, speciation brought about by geographic isolation —
   in this case from larger relatives on the mainland), combined with
   natural selection for smaller size because of the limited resources of
   the islands.
   Subspecies of Island Fox
   Enlarge
   Subspecies of Island Fox

   There are six subspecies of Island Fox, each of which is native to a
   specific Channel Island, and which evolved there independently of the
   others. The subspecies are
     * Urocyon littoralis littoralis of San Miguel Island,
     * Urocyon littoralis santarosae of Santa Rosa Island,
     * Urocyon littoralis santacruzae of Santa Cruz Island,
     * Urocyon littoralis dickeyi of San Nicolas Island,
     * Urocyon littoralis catalinae of Santa Catalina and
     * Urocyon littoralis clementae of San Clemente Island.

   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.

   Based on the limited fossil record and genetic distance from their Gray
   Fox ancestors, the northern Island Foxes are probably the older
   subspecies, while the San Clemente Island Foxes have been only resident
   on their island for about 3,400–4,300 years, and the San Nicolas Island
   Foxes established themselves as an independent group about 2,200 years
   ago. The Santa Catalina Island Foxes are potentially the most recently
   evolved subspecies, having been on their island for about 800–3,800
   years. The foxes did not persist on Anacapa Island because it has no
   reliable source of fresh water; Santa Barbara Island is too small to
   support the food demands of the foxes.
   A nighttime shot of an Island Fox with three mice in its jaws.
   Enlarge
   A nighttime shot of an Island Fox with three mice in its jaws.

Physical description

   The Island Fox is much smaller than the gray fox, roughly the size of a
   house cat, and is the second smallest of all foxes after the Fennec.
   Typically the head-and-body length is 48–50 cm (18–20 in.), shoulder
   height 12–15 cm (4–6 in.), and the tail is 11–29 cm (4–11 in.) long,
   which is notably shorter than the 27–44 cm (10–17 in.) tail of the Gray
   Fox. Island foxes weigh between 1.3 and 2.8 kg (2.8–6.2 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. 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.
   An Island Fox kit nestled in the brush.
   Enlarge
   An Island Fox kit nestled in the brush.

Reproduction

   Island Foxes typically form monogamous breeding pairs and are
   frequently seen together beginning in January and through the breeding
   season, from late February to early March. The gestation period is
   33–50 days. The Island Fox gives birth in a den, a typical litter
   having one to five kits, with an average of two or three. Kits 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 behaviour

   Their preferred habitat is complex layer vegetation with a high density
   of woody, perennially fruiting shrubs. The foxes live in all of the
   island biomes including temperate forest and rainforest, temperate
   grassland and chaparral, with no island supporting more than 1,000
   foxes. Island Foxes eat fruits, insects, birds, eggs, crabs, lizards,
   and small mammals, including the deer mouse. The foxes tend to move
   around by themselves, rather than in packs. They are generally diurnal,
   albeit with peaks of activity at dawn and dusk. Activity also
   fluctuates with the season; they are more active during the day in
   summer than they are in winter.

   Island Foxes are not intimidated by humans, as they have historically
   been at the top of the island food chain and had no natural predators.
   They are quite easy to tame and are generally docile. Island foxes
   communicate with each other using auditory, olfactory and visual
   signals. A dominant fox uses vocalizations, staring, and ear flattening
   to cause another fox to submit. They mark territory with urine and
   feces.

Conservation status

   A decline in Island Fox populations was identified in the 1990s. On San
   Miguel Island the decline began in 1994, the adult population falling
   from 450 to 15 in 1999. Similar population declines were discovered on
   Santa Cruz Island, where the population decreased from 2,000 adults in
   1994 to less than 135 in 2000, and on Santa Rosa Island where 1,500
   foxes recorded in 1994 were reduced to 14 animals by 2000. Golden Eagle
   predation, discovered when foxes were radio-collared and monitored,
   proved to be the cause of the high mortality rates.
   The Golden Eagle is four times the size of the Island Fox and can
   easily prey on the foxes.
   Enlarge
   The Golden Eagle is four times the size of the Island Fox and can
   easily prey on the foxes.

   Golden Eagle predation is the primary cause of Island Fox mortality.
   Golden Eagles were unknown in the Channel Islands before the 1990s, and
   the first Golden Eagle nest was recorded on Santa Cruz Island in 1999.
   Biologists propose that the eagle may have been attracted to the
   islands by the expanding populations of feral livestock (such as pigs),
   as well as the decimation of the local Bald Eagle population due to DDT
   exposure in the 1950s—the Bald Eagles would have deterred the Golden
   Eagles from settling on the islands while they themselves subsisted on
   fish.

   Introduced diseases or parasites can devastate Island Fox populations.
   Because Island Foxes are isolated they have no immunity to parasites
   and diseases brought in from the mainland and are especially vulnerable
   to those domestic dogs may carry. A canine distemper outbreak in 1998
   killed approximately 90% of Santa Catalina Island's fox population. (It
   is difficult to vaccinate against or treat foxes for parasites and
   disease in the wild.)

   Diminished food supply and general degradation of the habitat due to
   introduced mammal species, including feral cats, pigs, sheep, goats,
   and American Bison, the latter having been introduced to Catalina
   Island in the 1920s by a Hollywood film crew shooting a Western, also
   has had a negative effect on fox populations.

   The foxes threaten a population of severely endangered Loggerhead
   Shrikes in residence on San Clemente Island. The Island Fox population
   on San Clemente Island has been negatively affected by trapping and
   removal or euthanasia of foxes by the United States Navy. Since 2000,
   the Navy has employed different management strategies: trapping and
   holding foxes during the shrike breeding season, the installation of an
   electric fence system around shrike habitats, and the use of shock
   collar systems. With the gradual recovery of the shrike population on
   San Clemente Island, the Navy no longer controls the foxes. Automobile
   fatalities have also been high on San Clemente, San Nicolas, and Santa
   Catalina Islands.

Federal protection

   In March of 2004, four subspecies of the Island Fox were classified as
   a federally protected endangered species: the Santa Cruz Island Fox,
   Santa Rosa Island Fox, San Miguel Island Fox and the Santa Catalina
   Island Fox. The IUCN still lists them as "lower risk."
   Captive breeding programs are underway on all four islands with
   endangered Island Fox populations. This site is on Santa Rosa Island.
   Enlarge
   Captive breeding programs are underway on all four islands with
   endangered Island Fox populations. This site is on Santa Rosa Island.

   The National Parks Service has initiated captive fox breeding programs
   on San Miguel, Santa Rosa and Santa Cruz Islands, successfully
   increasing the numbers of resident foxes. In 2004, there were 38 San
   Miguel Island Foxes, all in captivity; 46 foxes in captivity on Santa
   Rosa Island and 7 in the wild (Golden Eagle predation prevented the
   release of captive foxes into the wild); Santa Cruz Island had 25
   captive foxes and a stable wild population of around 100 foxes. The
   Catalina Island Conservancy also runs a captive breeding program on
   Catalina Island; in 2002, there were 17 foxes in captive breeding
   programs and at least 161 wild foxes.

   A key to the recovery of the Island Fox is the removal of the Golden
   Eagle from the Channel Islands, ecosystem restoration and disease
   control. To ensure survival of the Island Fox, Golden Eagles are being
   moved from the northern islands to the mainland. Maintaining and
   increasing the Bald Eagle population on the islands would help to
   displace the Golden Eagle. However, the program is extremely
   resource-intensive and is at risk for cancellation. Removal of feral
   pigs from Catalina Island and Santa Cruz Island is underway, removing
   both the golden eagles food and competition for the Island Fox. To
   eliminate the risk of disease, pets are not permitted in Channel
   Islands National Park. A vaccination program has been initiated to
   protect Catalina Island foxes from canine distemper.

   Because the Channel Islands are almost entirely owned and controlled by
   either the Catalina Island Conservancy or the federal government, the
   fox has a chance to receive the protection it needs, including constant
   supervision by interested officials without the ongoing threat of human
   encroachment on its habitat.

   Retrieved from " http://en.wikipedia.org/wiki/Island_Fox"
   This reference article is mainly selected from the English Wikipedia
   with only minor checks and changes (see www.wikipedia.org for details
   of authors and sources) and is available under the GNU Free
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