Lycalopex fulvipes
Darwin's fox

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, Jimenez, and Jaksic, 1990)

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)

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The following average measurements are from unpublished data from J. E. Jimenez of Chiloe Island and C. McMahon of Nahuelbuta National Park and Chiloe Island that were provided in their report for the IUCN/SSC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

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

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)

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.

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)

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.

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)

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)

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)

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)

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)