Da'rwin's fox or Darwin's zorro (Lycalopex fulvipes) is an endangered canine from the genus Lycalopex. It is also known as the zorro chilote or zorro de Darwin in Spanish and lives on Nahuelbuta National Park (Araucanía Region), the Valdivian Coastal Range (Los Ríos Region) in mainland Chile and Chiloé Island. This small, dark canine weighs 1.8 to 3.95 kg (4.0 to 8.7 lb), has a head-and-body length of 48 to 59 cm (19 to 23 in) and a tail that is 17.5 to 25.5 cm (7 to 10 in).
Darwin's fox was first collected from San Pedro Island off the coast of Chile by the naturalist Charles Darwin in 1834. It was long held that Darwin's fox was a subspecies of the South American gray fox (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.
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).
The following average measurements are from unpublished data from J. E. Jimenez of Chiloe Island and C. McMahon of Nahuelbuta National Park and Chiloe Island that were provided in their report for the IUCN/SSC Canid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.
Darwin's fox has a vast diet. In dense forests, where it exists, the foxes hunt for mammals, reptiles, beetles, and invertebrates. Sometimes it selects fruits and berries. Birds and amphibians 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.
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 subspopulation (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.
Range and Habitat
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. 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).
Some evidence suggests that Darwin's foxes are monogamous (Jimenez, 2006). Not much is known about the mating behaviors of this species. 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.