Island fox
Island fox[1] | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Carnivora |
Family: | Canidae |
Genus: | Urocyon |
Species: | U. littoralis
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Binomial name | |
Urocyon littoralis (Baird, 1857)
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Google Range Map |
The island fox (Urocyon littoralis) is a small
Taxonomy and evolution
The island fox shares the
There are six subspecies of the island fox,[1] each of which is native to a specific Channel Island, and which evolved there independently of the others. The subspecies are:[1]
- U. l. littoralis (the nominate subspecies) of San Miguel Island,
- U. l. dickeyi of San Nicolas Island,
- U. l. catalinae of Santa Catalina Island,
- U. l. clementae of San Clemente Island,
- U. l. santacruzae of Santa Cruz Island, and
- U. l. santarosae of Santa Rosa Island.
Foxes from each island are capable of interbreeding, but have
The small size of the island fox is an adaptation to the limited resources available in the island environment, or
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 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.[10] 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.[11] The largest of the subspecies occurs on Santa Catalina Island and the smallest on Santa Cruz Island.[11]
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.
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 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.[11]
Genomic analysis
Island foxes have inhabited California's Channel Islands for more than 9,000 years, and have existed in small populations with low diversity for many generations.[13] Morphological analysis indicate an absence of inbreeding depression.[13] Apparently, the explanation for the absence of inbreeding depression is that, over the long-term, the small population size of island foxes facilitated a reduced burden of strongly deleterious recessive mutations through purging by natural selection.[13] Purging of deleterious recessive mutations occurs when their detrimental effect is expressed in homozygous individuals.
Ecology and behavior
Its preferred habitat is complex layer vegetation with a high density of woody, perennially fruiting shrubs. The fox lives in all of the island
The island fox is not intimidated by humans, although at first it may show aggression. It is quite easy to tame and is generally docile.
Conservation status and federal protection
In March 2004, four subspecies of the island fox were classified as a federally protected
Golden eagle predation, discovered when foxes were radio-collared and monitored, proved to be the cause of the high mortality rates.[22] The golden eagle was an uncommon visitor to the Channel Islands before the 1990s, when it naturally colonized the area, 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.[23] Biologists propose that the eagle may have been attracted to the islands in the 1960s after the decline of the bald eagle (Haliaeetus leucocephalus). The golden eagle replaced the bald eagle's niche and began to feed on feral pigs (Sus domesticus) following the devastation of the local bald eagle population due to DDT exposure in the 1950s—the bald eagle is hypothesized to have deterred the golden eagle from settling on the islands while it subsisted on fish.[22]
The feral pigs on Santa Rosa, which themselves preyed on the foxes, 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 diseases or parasites can devastate island fox populations. Because the island fox is isolated, it has not acquired immunity to
Diminished food supply and general degradation of the habitat due to
also has had a negative effect on fox populations.The foxes threaten a population of the severely endangered
The populations of Santa Cruz island foxes, San Miguel island foxes, and Santa Rosa island foxes have dramatically rebounded from lows in 2000 of 70 for the Santa Cruz foxes and 15 each on San Miguel and Santa Rosa Islands.[32] The Catalina Island Conservancy runs a captive breeding program on Catalina Island.[33] On September 14, 2012, the US Fish and Wildlife Service released a draft recovery plan for the San Miguel island fox, Santa Rosa island fox, Santa Cruz island fox, and the Santa Catalina island fox.[34] By 2012, the Catalina Island Conservancy determined that there were 1,500 Santa Catalina island foxes and the population was stable.[35] Since then the fox populations have grown.
Channel Island Name | #'s |
---|---|
San Miguel | 277 |
San Nicholas | 450 |
Santa Rosa | 2,657 |
Santa Cruz | 2,339 |
Santa Catalina | 1,807 |
San Clemente | 1,172 |
[28] [36] 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.
Rene Vellanoweth, an archaeologist, has proposed that inbreeding depression can be managed by mixing the different island fox subspecies populations much as the indigenous peoples did, by moving them from island to island, creating a higher genetic diversity and assisting them in recovery.[37]
See also
References
- ^ OCLC 62265494.
- ^ . Retrieved 9 March 2022.
- ^ "NatureServe Explorer 2.0". explorer.natureserve.org. Retrieved 20 April 2022.
- S2CID 251090119.
- ^ Beck, Christina (12 August 2016). "Endangered no more: California's island foxes make a surprising rebound". The Christian Science Monitor. Retrieved 15 August 2016.
- PMID 28563958.
- S2CID 4303549.
- ^ Collins, P.W. (1991). "Interaction between the island foxes (Urocyon littoralis) and Indians on islands off the coast of southern California. I Morphologic and archaeological evidence of human assisted dispersal" (PDF). Journal of Ethnobiology. 11: 51–82.
- PMID 25714775.
- ISBN 978-0-87156-377-4.
- ^ S2CID 215746001. Archived from the original(PDF) on 22 January 2012. Retrieved 16 September 2011.
- ^ Sillero-Zubiri, Claudio; Hoffman, Michael & MacDonald David W. (2004). Canids: Foxes, Wolves, Jackals, and Dogs (PDF) (Report). Status Survey and Conservation Action Plan. Gland, Switzerland; Cambridge, UK: IUCN. p. 98.
- ^ a b c Robinson JA, Brown C, Kim BY, Lohmueller KE, Wayne RK. Purging of Strongly Deleterious Mutations Explains Long-Term Persistence and Absence of Inbreeding Depression in Island Foxes. Curr Biol. 2018 Nov 5;28(21):3487-3494.e4. doi: 10.1016/j.cub.2018.08.066. Epub 2018 Oct 25. PMID: 30415705; PMCID: PMC6462144
- ^ "Urocyon littoralis (Island gray fox)". Animal Diversity Web.
- ^ "Urocyon littoralis (Island gray fox)". Animal Diversity Web.
- ^ "Urocyon littoralis (Island gray fox)". Animal Diversity Web.
- ^ "Urocyon littoralis (Island gray fox)". Animal Diversity Web.
- ^ a b "Island Fox". Channel Islands National Park. National Park Services. Retrieved 18 January 2013.
- ^ Proposed Designation of Critical Habitat for the San Miguel Island Fox, Santa Rosa Island Fox, Santa Cruz Island Fox, and Santa Catalina Island Fox (Report). Endangered and Threatened Wildlife and Plants. U.S. Environmental Protection Agency. 2004.
- ^ Roemer, G. W.; Garcelon, D. K.; Coonan, T. J. & Schwemm, C. (1994). "The use of capture–recapture methods for estimating, monitoring, and conserving island fox populations" (PDF). In Halvorsen, W. L. & Maender, G. J. (eds.). The Fourth California Islands Symposium: Update on the Status of Resources. Santa Barbara, California: Santa Barbara Museum of Natural History. pp. 387–400.
- ^ a b Coonan, T. J.; et al. (2004). 2003 Annual Report (Report). Island fox recovery program. Channel Islands National Park, California: National Park Service.
- ^ PMID 11752396.
- ^ a b "Home Page". Nps.gov. Channel Islands National Park's Island Fox. 13 August 2010. Retrieved 16 September 2011.
- ^ Collins, P. W.; Latta, B. C. (2006). Nesting Season Diet of Golden Eagles on Santa Cruz and Santa Rosa Islands, Santa Barbara County, California (PDF) (Report). Technical Report. Vol. 3. Santa Barbara Museum of Natural History.
- S2CID 12119293.
- ^ Dawn, Karen (2008). Thanking the Monkey: Rethinking the way we treat animals (1st ed.). HarperCollins. p. 300.
- ^ Recovery of the Catalina Island Fox (Report). Avalon, California: Catalina Island Conservancy.
- ^ a b Armario, Christine (12 February 2016). "Feds: Remove 3 California Foxes from Endangered Species List". Los Angeles, CA. Associated Press. Retrieved 15 February 2016.
- ^ Sahagun, Louis (19 January 2012). "Catalina Island fox makes astounding comeback". Los Angeles Times. Retrieved 21 January 2012.
- ^ Chang, Alicia (21 September 2007). "Study: Catalina bison aren't purebred". USA Today. Associated Press. Retrieved 14 March 2008.
- ^ San Clemente Island Range Complex Environmental Impact Study (PDF) (Report). United States Navy. 2000. Archived from the original (PDF) on 6 February 2007.
San Clemente Loggerhead numbers on the increase
- ^ Flaccus, Gillian (20 May 2013). "Rare island fox on the rebound from near-extinction". Bakersfield Now. Archived from the original on 7 January 2014. Retrieved 1 July 2013.
- ^ Kohlmann, S. G.; et al. (2003). Island fox recovery efforts on Santa Catalina Island, California, October 2001 – October 2002. Ecological Restoration Department (Report). Annual Report. Avalon, California: Santa Catalina Island Conservancy.
- ^ Draft Recovery Plan for Four Subspecies of Island Fox (Urocyon littorialis) (PDF) (Report). U.S. Fish and Wildlife Service. Retrieved 17 January 2013.
- ^ "Catalina fox population stabilizes, still endangered". abc7.com. KABC-TV/DT. 25 March 2013. Archived from the original on 27 March 2013. Retrieved 3 April 2013.
- ^ Friends of the Island Fox, 2021 Island Fox Status Update accessed 2023
- S2CID 84017699.
External links
Urocyon littoralis
(Island fox).