Island Fox
Encyclopedia
The island fox is a small fox
that is native to six of the eight Channel Islands of California
. There are six subspecies of the fox, each unique to the island it lives on, 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.
genus
with the mainland gray fox
, the species from which it is descended. Its small size is a result of insular dwarfism
, a kind of allopatric speciation
. 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 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.
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.
Based on the limited fossil record and genetic distance from its gray fox ancestors, the northern island fox subspecies are probably the older subspecies, while the San Clemente island fox has been only resident on its island for about 3,400–4,300 years, and the San Nicolas island fox established itself as an independent group about 2,200 years ago. The Santa Catalina island fox is potentially the most recently evolved subspecies, having been on its island for about 800–3,800 years. The fox 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 fox.
and kit fox
es. 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. 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. 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.
period is 50–63 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.
Its preferred habitat is complex layer vegetation with a high density of woody, perennially fruiting shrubs. The fox lives in all of the island biome
s including temperate forest, temperate grassland
and chaparral
, with no island supporting more than 1,000 foxes. The island fox eats fruit
s, insect
s, bird
s, eggs
, crab
s, lizard
s, and small mammal
s, including deer mice
. The fox tends to move around by itself, rather than in packs. It is generally nocturnal
, albeit 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. The island fox marks territory with urine and feces.
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 foxes may have numbered more than 1,500 in 1994 but 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.
Golden eagle
predation is the primary cause of island fox mortality. The golden eagle was an uncommon visitor to the Channel Islands before the 1990s according to data gathered by Dr. Lyndal Laughrin of the University of California Santa Cruz Island Reserve, 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 in the 1960s after the decline of the bald eagle
. The golden eagle replaced the bald eagle and began to feed on feral pigs due to the decimation of the local bald eagle population due to DDT
exposure in the 1950s—the bald eagle would have deterred the golden eagle from settling on the islands while it subsisted on fish.
The feral pigs on Santa Rosa were exterminated by the National Park Service in the early 1990s which removed one of the golden eagle's food sources. The golden eagle then began to prey on the island fox population. Feral pigs on Santa Cruz Island and introduced deer and elk on Santa Rosa Island were introduced almost seventy years prior to island fox decline, therefore, the golden eagle most likely did not seek these animals as alternative prey. This has occurred most likely as a result of a process known as 'apparent competition'. In this process, a predator, like the golden eagle, feeds on at least two prey, for example, the island fox and feral pigs. One prey item is adapted to high predation pressure and supports the predator population (i.e. pigs), whereas the other prey item (i.e. the island fox) is poorly adapted to predation and declines as a consequence of the predation pressure. It has also been proposed that complete removal of golden eagles may be the only action that could save three subspecies of the island fox from extinction.
Introduced diseases or parasites can devastate island fox populations. Because the island fox is isolated, it has no immunity to parasites and diseases brought in from the mainland and are especially vulnerable to those the domestic dog 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 the severely endangered loggerhead shrike
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.
: the Santa Cruz island fox, Santa Rosa island fox, San Miguel island fox and the Santa Catalina island fox. The IUCN
lists the entire species as critically endangered
.
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 eagle's 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, The Nature 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.
According to the Nature Conservancy summer 2009 magazine, the Santa Cruz Island fox population has rebounded to a population of 700 from being fewer than 100.
While it has been assumed that the foxes existed on these islands long before native people settled on the islands, archaeologists are now challenging this theory. Rene Vellanoweth believes that the foxes were brought to the island with the indigenous people, and had not been there upon their arrival. Vellanoweth also believes that the foxes were moved from island to island with the people, which caused interbreeding amongst the species. He believes the key to restarting the fox population is to do what the indigenous people did: mix their species and move them from island to island, creating a higher genetic diversity and assisting them in recovery.
Fox
Fox is a common name for many species of omnivorous mammals belonging to the Canidae family. Foxes are small to medium-sized canids , characterized by possessing a long narrow snout, and a bushy tail .Members of about 37 species are referred to as foxes, of which only 12 species actually belong to...
that is native to six of the eight Channel Islands of California
Channel Islands of California
The Channel Islands of California are a chain of eight islands located in the Pacific Ocean off the coast of Southern California along the Santa Barbara Channel in the United States of America...
. There are six subspecies of the fox, each unique to the island it lives on, 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.
Taxonomy and evolution
The island fox shares the UrocyonUrocyon
The genus Urocyon is a genus that contains two living Western Hemisphere foxes in the family Canidae, the Gray Fox and the closely related Island Fox which is a dwarf cousin of the Gray Fox; as well as one fossil species, Urocyon progressus.Urocyon and the...
genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
with the mainland gray fox
Gray Fox
The gray fox is a mammal of the order Carnivora ranging throughout most of the southern half of North America from southern Canada to the northern part of South America...
, the species from which it is descended. Its small size is a result of insular dwarfism
Insular dwarfism
Insular dwarfism, a form of phyletic dwarfism, is the process and condition of the reduction in size of large animals – typically mammals – when their population's range is limited to a small environment, primarily islands. This natural process is distinct from the intentional creation of dwarf...
, a kind of allopatric speciation
Allopatric speciation
Allopatric speciation or geographic speciation is speciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration...
. Because the island fox is geographically isolated, it has no immunity
Immunity (medical)
Immunity is a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide...
to parasites and diseases brought in from the mainland and is especially vulnerable to those the domestic dog may carry. In addition, predation by the golden eagle
Golden Eagle
The Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
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
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
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.
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:
- Urocyon littoralis littoralis of San Miguel IslandSan Miguel IslandSan Miguel Island is the westernmost of California's Channel Islands, located across the Santa Barbara Channel in the Pacific Ocean, within Santa Barbara County, California. San Miguel is the sixth-largest of the eight Channel Islands at , including offshore islands and rocks. Prince Island, off...
, - Urocyon littoralis santarosae of Santa Rosa IslandSanta Rosa Island, CaliforniaSanta Rosa Island is the second largest of the Channel Islands of California at 53,195 acres . Defined by the United States Census Bureau as Block 3009, Block Group 3, Census Tract 29.10 of Santa Barbara County, California, the 2000 census showed an official population of 2 persons. It is part of...
, - Urocyon littoralis santacruzae of Santa Cruz IslandSanta Cruz IslandSanta Cruz Island was the largest privately owned island off the continental United States, but is currently part-owned by the National Park service . The island, located off the coast of California, is long and from wide...
, - Urocyon littoralis dickeyi of San Nicolas IslandSan Nicolas IslandSan Nicolas Island is the most remote of California's Channel Islands. It is part of Ventura County. The 14,562 acre island is currently controlled by the United States Navy and is used as a weapons testing and training facility, served by Naval Outlying Field San Nicolas Island...
, - Urocyon littoralis catalinae of Santa CatalinaSanta Catalina Island, CaliforniaSanta Catalina Island, often called Catalina Island, or just Catalina, is a rocky island off the coast of the U.S. state of California. The island is long and across at its greatest width. The island is located about south-southwest of Los Angeles, California. The highest point on the island is...
and, - Urocyon littoralis clementae of San Clemente IslandSan Clemente IslandSan Clemente Island is the southernmost of the Channel Islands of California. It is owned and operated by the United States Navy, and is a part of Los Angeles County. Defined by the United States Census Bureau as Block Group 2 of Census Tract 5991 of Los Angeles County, California, it is long and...
.
Foxes from each island are capable of interbreeding, but have genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and phenotypic
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
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
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
—when lowered sea levels united four of the northernmost islands into a single mega-island (Santa Rosae
Santa Rosae
Santa Rosae was an ancient landmass off the coast of present-day southern California, near Ventura County and Santa Barbara County, of which the northern Channel Islands of California are remnants....
) and the distance between the islands and the mainland was reduced—it is likely that Native Americans
Indigenous peoples of the Americas
The indigenous peoples of the Americas are the pre-Columbian inhabitants of North and South America, their descendants and other ethnic groups who are identified with those peoples. Indigenous peoples are known in Canada as Aboriginal peoples, and in the United States as 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 its gray fox ancestors, the northern island fox subspecies are probably the older subspecies, while the San Clemente island fox has been only resident on its island for about 3,400–4,300 years, and the San Nicolas island fox established itself as an independent group about 2,200 years ago. The Santa Catalina island fox is potentially the most recently evolved subspecies, having been on its island for about 800–3,800 years. The fox did not persist on Anacapa Island
Anacapa Island
Anacapa Island is a small volcanic island located about off the coast of Port Hueneme, California, in Ventura County. The Island is composed of a series of narrow islets six miles long, running in a mostly east-west orientation, five miles east of Santa Cruz Island...
because it has no reliable source of fresh water; Santa Barbara Island
Santa Barbara Island
Santa Barbara Island is a small island of the Channel Islands archipelago in California. It is located about off the Southern California coast from the Palos Verdes Peninsula, near Los Angeles in Ventura County, California....
is too small to support the food demands of the fox.
Description
The island fox is significantly smaller than the gray fox and perhaps the smallest fox in North America, averaging slightly smaller than the swiftSwift Fox
The swift fox is a small light orange-tan fox around the size of a domestic cat found in the western grasslands of North America, such as Colorado, New Mexico and Texas. It also lives in Manitoba, Saskatchewan and Alberta in Canada, where it was previously extirpated...
and kit fox
Kit Fox
The kit fox is a fox species of North America. Its range is primarily in the southwestern United States and northern and central Mexico. Some mammalogists classify it as conspecific with the swift fox, V. velox, but molecular systematics imply that the two species are distinct.-Range:The...
es. 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. 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. 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.
Reproduction
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 gestationGestation
Gestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
period is 50–63 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 behavior
Biome
Biomes are climatically and geographically defined as similar climatic conditions on the Earth, such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems. Some parts of the earth have more or less the same kind of abiotic and biotic factors spread over a...
s including temperate forest, temperate grassland
Grassland
Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found. Grasslands occur naturally on all continents except Antarctica...
and chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
, with no island supporting more than 1,000 foxes. The island fox eats fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
s, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s, eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...
s, and small mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, including deer mice
Peromyscus
The genus Peromyscus contains the animal species commonly referred to as deer mice. This is a genus of New World mouse only distantly related to the common house mouse and laboratory mouse, Mus musculus...
. The fox tends to move around by itself, rather than in packs. It is generally nocturnal
Nocturnal animal
Nocturnality is an animal behavior characterized by activity during the night and sleeping during the day. The common adjective is "nocturnal"....
, albeit 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. The island fox marks territory with urine and feces.
Conservation status
Golden Eagle
The Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
predation, discovered when foxes were radio-collared and monitored, proved to be the cause of the high mortality rates.
Golden eagle
Golden Eagle
The Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...
predation is the primary cause of island fox mortality. The golden eagle was an uncommon visitor to the Channel Islands before the 1990s according to data gathered by Dr. Lyndal Laughrin of the University of California Santa Cruz Island Reserve, 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 in the 1960s after the decline of the bald eagle
Bald Eagle
The Bald Eagle is a bird of prey found in North America. It is the national bird and symbol of the United States of America. This sea eagle has two known sub-species and forms a species pair with the White-tailed Eagle...
. The golden eagle replaced the bald eagle and began to feed on feral pigs due to the decimation of the local bald eagle population due to DDT
DDT
DDT is one of the most well-known synthetic insecticides. It is a chemical with a long, unique, and controversial history....
exposure in the 1950s—the bald eagle would have deterred the golden eagle from settling on the islands while it subsisted on fish.
Introduced diseases or parasites can devastate island fox populations. Because the island fox is isolated, it has no immunity to parasites and diseases brought in from the mainland and are especially vulnerable to those the domestic dog may carry. A canine distemper
Canine distemper
Canine distemper is a viral disease that affects animals in the families Canidae, Mustelidae, Mephitidae, Hyaenidae, Ailuridae, Procyonidae, Pinnipedia, some Viverridae and Felidae...
outbreak in 1998 killed approximately 90% of Santa Catalina Island's fox population. (It is difficult to vaccinate
Vaccination
Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
against or treat foxes for parasites and disease in the wild.)
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
, including feral
Feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
cats, pigs, sheep, goats, and American bison
American Bison
The American bison , also commonly known as the American buffalo, is a North American species of bison that once roamed the grasslands of North America in massive herds...
, 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 the severely endangered loggerhead shrike
Loggerhead Shrike
The Loggerhead Shrike is a passerine bird. It is the only member of the shrike family endemic to North America; the related Northern Shrike occurs north of its range but also in the Palearctic....
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
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
. 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 2004, four subspecies of the island fox were classified as a federally protected endangered speciesEndangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
: the Santa Cruz island fox, Santa Rosa island fox, San Miguel island fox and the Santa Catalina island fox. The IUCN
World Conservation Union
The International Union for Conservation of Nature and Natural Resources is an international organization dedicated to finding "pragmatic solutions to our most pressing environment and development challenges." The organization publishes the IUCN Red List, compiling information from a network of...
lists the entire species as critically endangered
Critically endangered
Version 2010.3 of the IUCN Red List of Threatened Species identified 3744 Critically Endangered species, subspecies and varieties, stocks and subpopulations.Critically Endangered by kingdom:*1993 Animalia*2 Fungi*1745 Plantae*4 Protista-References:...
.
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 eagle's food and competition for the island fox. To eliminate the risk of disease, pets are not permitted in Channel Islands National Park
Channel Islands National Park
- External links :* Official site: * *...
. 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, The Nature 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.
According to the Nature Conservancy summer 2009 magazine, the Santa Cruz Island fox population has rebounded to a population of 700 from being fewer than 100.
While it has been assumed that the foxes existed on these islands long before native people settled on the islands, archaeologists are now challenging this theory. Rene Vellanoweth believes that the foxes were brought to the island with the indigenous people, and had not been there upon their arrival. Vellanoweth also believes that the foxes were moved from island to island with the people, which caused interbreeding amongst the species. He believes the key to restarting the fox population is to do what the indigenous people did: mix their species and move them from island to island, creating a higher genetic diversity and assisting them in recovery.