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Darwin's fox or Darwin's zorro (''Lycalopex fulvipes'') is an
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
canid Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...
from the genus '' Lycalopex''. It is also known as the ''zorro chilote'' or ''zorro de Darwin'' in Spanish and lives in Nahuelbuta National Park, the Cordillera de Oncol, Cordillera Pelada in mainland
Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...
and
Chiloé Island Chiloé Island (, , ), also known as Greater Island of Chiloé (''Isla Grande de Chiloé''), is the largest island of the Chiloé Archipelago off the west coast of Chile, in the Pacific Ocean. The island is located in southern Chile, in the Los L ...
. This small, dark canine weighs , has a head-and-body length of and a tail that is . Darwin's fox displays no key differences between male and female other than the fact that the male has a broader muzzle. Males display no territorial behavior and are not aggressive towards other males roaming around their territory. Darwin's fox was first collected from San Pedro Island off the coast of Chile by the naturalist
Charles Darwin Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English Natural history#Before 1900, naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all speci ...
, in 1834, hence, the name- Darwin's Fox. It was long held that Darwin's fox was a subspecies of the
South American gray fox The South American gray fox (''Lycalopex griseus''), also known as the Patagonian fox, the ''chilla'' or ''zorro gris'' (gray fox or gray zorro), is a South America, South American species of ''Lycalopex'' (the "false" or lesser foxes) in the Ca ...
(''L. griseus''); however, the discovery of a small population of Darwin's fox on the mainland in Nahuelbuta National Park, in 1990 and subsequent genetic analysis has clarified the fox's status as a unique species. In 2012 and 2013, the presence of the Darwin's fox at Oncol Park, Alerce Costero National Park and the Valdivian Coastal Reserve was confirmed through camera trapping.


Taxonomy and evolution

''Lycalopex'' is a
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...
n genus of canine, which is distantly related to wolves and is technically not a fox. When Charles Darwin collected a specimen from San Pedro Island in
Chiloé Archipelago The Chiloé Archipelago (, , ) is a group of islands lying off the coast of Chile, in the Los Lagos Region. It is separated from mainland Chile by the Chacao Channel in the north, the Sea of Chiloé in the east and the Gulf of Corcovado in the s ...
in December, 1834, during the ''Beagle'' survey expedition, he observed that this "fox (of Chiloe, a rare animal) sat on the point & was so absorbed in watching urvey work that he allowed me to walk behind him & actually kill him with my geological hammer." Keynes, R. D. ed. 2001. ''Charles Darwin's Beagle diary''. Cambridge: Cambridge University Press. pp
272–273
/ref> In the 1839, publication of his '' Journal and Remarks'', Darwin said "This fox, more curious or more scientific, but less wise, than the generality of his brethren, is now mounted in the museum of the Zoological Society." He said it was "an undescribed species,"Darwin, C. R. 1839. ''Narrative of the surveying voyages of His Majesty's Ships Adventure and Beagle between the years 1826 and 1836, Journal and Remarks 1832–1836''. London: Henry Colburn. p
341
/ref> indicating that it was distinct from the species ( ''L. culpaeus'' and ''L. griseus'') that occur on the mainland. Later, Darwin's fox was classified as a subspecies (''Lycalopex griseus fulvipes'') of the latter. Darwin's fox does not
interbreed In biology, a hybrid is the offspring resulting from combining the qualities of two organisms of different variety (botany), varieties, subspecies, species or genus, genera through sexual reproduction. Generally, it means that each cell has gene ...
with the other ''Lycalopex'' species, only lives in forests, and is smaller and darker-colored than the other species. In 1990, a small population of Darwin's fox was found on the mainland in the forested Nahuelbuta National Park, indicating that the fox was not endemic to the island. According to Yahnke et al., in their 1996 article, published in the Journal of the Society for Conservation Biology, analysis of mitochondrial DNA of Darwin's fox and the gray fox showed two patterns, indicating Darwin's fox was a new species, closely related to the Sechuran fox. Also according to Yahnke (1995; et al.1996) the present restricted range is a relic of a much wider former range. Zoologists noted the distinctiveness in the ecological niche, appearance, and behavior of this species. Darwin's fox is differentiated from the
gray fox The gray fox (''Urocyon cinereoargenteus''), or grey fox, is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. This species and its only congener (biology), congener, the diminutive island fox ...
in being darker; having shorter legs; a broader, shorter skull; smaller auditory bullae; a more robust dentition; and a different jaw shape and style of premolar occlusion. In the late
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
, Chiloé Island was connected to mainland Chile by a land bridge. The land bridge was severed about 15,000 years ago when the sea level rose following the last glaciation. This created two isolated populations of Darwin's fox.


Diet

Darwin's fox has a vast diet. In dense forests, where it exists, the foxes hunt for mammals,
reptile Reptiles, as commonly defined, are a group of tetrapods with an ectothermic metabolism and Amniotic egg, amniotic development. Living traditional reptiles comprise four Order (biology), orders: Testudines, Crocodilia, Squamata, and Rhynchocepha ...
s,
beetle Beetles are insects that form the Taxonomic rank, order Coleoptera (), in the superorder Holometabola. Their front pair of wings are hardened into wing-cases, elytra, distinguishing them from most other insects. The Coleoptera, with about 40 ...
s, and
invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...
s. Sometimes it selects
fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
s,
berries A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone fruit, stone or pit (fruit), pit although many wikt:pip#Etymology 2, pips or seeds may be p ...
, and
seed In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...
s.
Bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
s and
amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...
s to a lesser degree are also consumed. It sometimes eats carrion, but it mostly eats live animals and fruit. This makes it mostly an omnivore, sometimes a scavenger.


Ecology

Darwin's fox is generally believed to be a forest obligate species found only in southern temperate rainforests. They only occur in areas of primary forest on Chiloé and on the mainland. They are most active at twilight and before sunrise. In contrast to other ''Lycalopex'' species, Darwin's fox prefers open spaces. The population of Chiloé has about 200 individuals, and Nahuelbuta on the mainland contains about 50 individuals. The total population size is about 250 mature individuals with at least 90% of the population occurring in one subpopulation (Chiloé Island). Although the species is protected in Nahuelbuta National Park, substantial mortality sources exist when foxes move to lower, unprotected private areas in search of milder conditions during the winter. The population was considered as critically endangered because its main population occurred in one island and their habitat was declining due to human impact.


Conservation status

The species was previously classified as
Critically Endangered An IUCN Red List critically endangered (CR or sometimes CE) species is one that has been categorized by the International Union for Conservation of Nature as facing an extremely high risk of extinction in the wild. As of December 2023, of t ...
by the
IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...
, but in 2016 was downlisted to
Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...
, as its area occurrences is apparently substantially larger than originally believed. Current estimates of the total population are still low, with an estimated minimum 227 individuals on the mainland and 412 on Chiloé Island. Fragmentation of forest adjacent to the national park and on the island is a concern for their conservation, and feral dogs may pose the greatest threat to their survival by spreading disease or directly attacking. Persecution by people who think that the foxes attack domestic fowls, though they pose little threat, is also a potential problem.


Diseases

The species is often plagued by '' Mycoplasma haemocanis''. The already endangered fox is prone to this
infection An infection is the invasion of tissue (biology), tissues by pathogens, their multiplication, and the reaction of host (biology), host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmis ...
because the infection's bacteria attach themselves to surface red blood cells of many mammals, and although the species is believed to be no major threat to human life it can spread to humans, dogs, cats, and other wildlife species. The bacteria also seem to spike when located close to any major habitat inhabited by humans as well as where there is a large population of wild dogs present near the species. Researchers are testing RNA subunits of RNase P gene and out of 10 foxes, nine were infected. Even though they are considered "sick", they have no external symptoms (Cabello, 2013). Studies show that many foxes risk of catching the deadly bacteria inclines as they age leaving many older foxes vulnerable. Although the disease is prevalent in this species, little to nothing is known about this disease.


References

{{Taxonbar, from=Q631167 Darwin's fox Mammals of Chile Mammals of Patagonia Chiloé Archipelago Endangered animals Endangered biota of South America Darwin's fox Darwin's fox Endemic fauna of Chile Fauna of the Valdivian temperate forests