Lycalopex fulvipesDarwin's fox

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Geographic Range

Darwin's foxes, Lycalopex fulvipes, are endemic to Chile and were once thought only to inhabit Chiloe Island, which is located off the southern coast. The island is over 200 km long and about 30 km west of Chile. Darwin’s foxes are found on most of the island, except in areas to the north where the island is populated by humans. In the 1970’s a mainland population was discovered at Nahuelbuta National Park in Chile (Medel et al., 1990). The park is about 600 km north of Chiloe Island. (Medel, et al., 1990)

Habitat

Darwin’s foxes prefer secondary forest to old growth in areas typical to temperate rainforest vegetation. On Chiloe Island the forest is of Valdivian type. It contains conifer species, a few evergreen species, and fruit-bearing trees. The northern and eastern areas of the island are inhabited by humans and agriculture has had some impact on the landscape. On the west coast of the island, the fox actively uses an evergreen forest habitat fragmented by sand dunes. The mainland population is found in dense forest containing monkey-puzzle trees (Araucaria araucaria) and five species of beech (Jimenez and McMahon, 2004).

In Nahuelbuta National Park elevation ranges from 950 to 1462 meters (Jaksic et al., 1990). (Jaksic, et al., 1990; Jimenez and McMahon, 2004)

Physical Description

Darwin’s foxes are characterized by their short legs, elongated body, and short and bushy tails. Their pelage is a mixture of black and grey hair with rufescent markings on the ears and along the lower portion of the legs. White or light markings can be found under the chin and along the underbelly. There are no significant data supporting sexual dimorphism. However, in a comparison done by Jimenez (2006), males did have a larger separation between the upper canines leading to the appearance of a broader muzzle. Dental formula is 3/3-1/1-4/4-2/3 = 42 (Jimenez and McMahon, 2004). (Jimenez and McMahon, 2004; Jimenez, 2006)

The following average measurements are from unpublished data from J. E. Jimenez of Chiloe Island and C. McMahon of Nahuelbuta National Park and Chiloe Island that were provided in their report for the IUCN/SSC Canid Specialist Group (2004):

Head and Body Length: 528 mm Tail Length: 221 mm Hind Foot: 106 mm Ear Length: 260 mm Mass: 2.72 kg (Jimenez and McMahon, 2004)

  • Sexual Dimorphism
  • sexes alike
  • Average mass
    2.72 kg
    5.99 lb
  • Average length
    528 mm
    20.79 in

Reproduction

Some evidence suggests that Darwin's foxes are monogamous (Jimenez, 2006). Not much is known about the mating behaviors of this species. (Jimenez, 2006)

Breeding season begins in October and pups have been documented leaving the den in December. Based on observations of dens, estimated litter size is 2 to 3 individuals (Jimenez and McMahon, 2004). Weaning takes place in February. Most inferences concerning breeding time come from observations on lactating females caught during trapping of island and mainland populations. (Jimenez and McMahon, 2004)

  • Breeding interval
    Darwin's foxes breed once yearly.
  • Breeding season
    Breeding occurs in the austral spring.
  • Range number of offspring
    2 to 3

Darwin's foxes show biparental care and the offspring share their parent’s home range for an undetermined amount of time. Parents share their ranges with offspring from previous litters but no observations so far suggest that these offspring contribute as helpers. (Jimenez and McMahon, 2004)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female

Lifespan/Longevity

Several individuals monitored in ongoing research have estimated ages up to seven years. (Jimenez and McMahon, 2004)

  • Range lifespan
    Status: wild
    7 (high) years

Behavior

Individuals are active during the day and at night with no variation among the sexes. Individuals are solitary outside the breeding season. Darwin’s foxes appear to be non-territorial.

Home Range

Home range sizes vary widely among individuals with much overlap within the population. Variability was not attributed to gender (Jimenez, 2006). These foxes are non-territorial and often share their home and core ranges with other foxes. Parents share home ranges with their offspring. Dispersal of young may be hindered by availability of open range areas, therefore young may stay within their parents’ home range until an opportunity becomes available (Jimenez and McMahon, 2004). (Jimenez and McMahon, 2004; Jimenez, 2006)

Communication and Perception

No information on communication within this species has been published. Like other canids, however, they are likely to use olfactory cues, vocalizations, and postural communication extensively. Canids in general have keen senses of smell, hearing, and touch.

Food Habits

Darwin’s foxes are omnivorous and opportunistic. Their diet varies seasonally with food availability. Their diet contains a variety of food items including small mammals, birds, reptiles, insects, fruits, and seeds. Data from scat analysis show that insects are the most abundant food item but that small mammals make up the largest amount of biomass in the diet. Although Darwin’s foxes may congregate at the site of a carcass, they are mainly solitary hunters. In areas where South American gray foxes (Lycalopex griseus) are present, Darwin’s foxes are more active at night, when South American gray foxes are less active. (Jimenez and McMahon, 2004)

  • Animal Foods
  • birds
  • mammals
  • amphibians
  • insects
  • aquatic crustaceans
  • Plant Foods
  • seeds, grains, and nuts
  • fruit

Predation

Possible predators of the mainland population of Darwin foxes are pumas (Puma concolor). Large raptors may also prey on these foxes, especially young foxes. However, predation on Darwin foxes has not been described in the literature.

Ecosystem Roles

The diet of Darwin's foxes includes a large portion of seeds. It has been suggested that these foxes may be seed dispersers for several plant species. (Jimenez and McMahon, 2004)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

No economic importance is proposed for this species. Trapping for fur is not reported. The uniqueness of these foxes may make them an ecotourism attraction. (Jimenez and McMahon, 2004)

Economic Importance for Humans: Negative

There are no known adverse effects of the Darwin's foxes on humans. They exhibit a lack of fear for humans in urban areas. On the island they inhabit these foxes have been accused of killing poultry . (Jimenez and McMahon, 2004)

Conservation Status

Most recent estimates place total population sizes at less than 100 individuals in the mainland population and approximately 500 individuals in the island population (Jimenez and McMahon, 2004). The size of the mainland population has been estimated to be on the rise, possibly due to a decrease in number of South American gray foxes (Lycalopex griseus) in the area (Jaksic et al., 1990). A study done by Jimenez (cited by Jimenez and McMahon, 2004) calculated the ecological density of a coastal population on Chiloe Island to be 0.92 foxes km2. This high density was attributed to the large overlap in the territories of these foxes. Agriculture plays a role in limiting the range of Darwin’s foxes in the island and mainland populations. Deforestation rates are limiting the range of these foxes, especially on the mainland where Nahuelbuta National Park is surrounded by agriculture and degraded habitat. On the island these foxes show little to no fear of humans and reports of foxes getting into houses to search for food are not uncommon. Domestic dogs may also present a problem in spreading disease to fox populations (Jimenez and McMahon, 2004). (Jaksic, et al., 1990; Jimenez and McMahon, 2004)

Other Comments

Charles Darwin collected the first specimen in 1834. He wrote, “he was so intently absorbed in watching the work of the officers, that I was able, by quietly walking up behind, to knock him on the head with my geological hammer” (Darwin, 1962, p. 281). (Darwin, 1962)

Lycalopex fulvipes was originally placed in the genus Vulpes by Martin in 1837. It was also placed in the genus Dusicyon. Until the discovery of the continental population, Darwin’s foxes were considered an island population of South American gray foxes (Pseudalopex griseus). Further study of the continental population revealed that Darwin's foxes lived in sympatry with South American gray foxes, leading to the elevation of Darwin’s foxes to its own species. A study based on mtDNA supported the separation from South American gray foxes (Yahnke, et al. 1996). The results also suggested that current populations are descended from a population that had a broad range in southern Chile before the split of Chiloe Island from the mainland in the late Pleistocene. It is thought that degradation of forest habitats has slowly limited the distribution of these foxes. A study by C. Vila et al. (2004) attempted to assess the possibility of other small populations in the forest areas between Naheulbuta National Park and Chiloe Island but no conclusive evidence was found to support this. (Vila, et al., 2004; Yahnke, et al., 1996)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Charlene Fortner (author), University of Alaska Fairbanks, Link Olson (editor, instructor), University of Alaska Fairbanks.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

fertilization

union of egg and spermatozoan

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

internal fertilization

fertilization takes place within the female's body

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

omnivore

an animal that mainly eats all kinds of things, including plants and animals

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

References

Darwin, C. 1962. The voyage of the Beagle. London: Doubleday.

Jaksic, F., J. Jimenez, R. Medel, P. Marquet. 1990. Habitat and diet of Darwin's fox (Pseudalopex fulvipes) on the Chilean mainland. Journal of Mammalogy, 71: 246-248.

Jimenez, J. 2006. Ecology of a coastal population of the critically endangered Darwin's fox (Pseudalopex fulvipes) on Chiloe Island, southern Chile. Journal of Zoology.

Jimenez, J., E. McMahon. 2004. Darwin’s fox Pseudalopex fulvipes (Martin, 1837). In Canids: foxes, wolves, jackals and dogs. Status survey and conservation action plan. IUCN/SSC Canid Specialist Group: 50-55. Gland and Oxford: IUCN/SSC Canid Specialist Group.

Medel, R., J. Jimenez, F. Jaksic. 1990. Discovery of a continental population of the rare Darwin's fox, Dusicyon fulvipes (Martin, 1837) in Chile. Biological Conservation, 51: 71-77.

Vila, C., J. Leonard, A. Iriarte, S. O'Brien, W. Johnson, R. Wayne. 2004. Detecting the vanishing populations of the highly endangered Darwin's fox, Pseudalopex fulvipes. Animal Conservation, 7: 147-153.

Yahnke, C., W. Johnson, E. Geffen, D. Smith, F. Hertel, M. Roy, C. Bonacic, T. Fuller, B. van Valkenburgh, R. Wayne. 1996. Darwin's fox: a distinct endangered species in a vanishing habitat. Conservation Biology, 10: 366-375.