Populations of Lepus californicus in what appears to be the same climate, vegetation, and other physical surroundings on the mainland exhibit no sign of melanism. The isolation of L. insularis on Espiritu Santo Island, combined with the virtual absence of predatory birds and mammals, has apparently removed selection pressure favoring cryptic coloration.
Lepus insularis is a close relative of L. californicus of the nearby peninsula of Baja California. The species-level status of L. insularis has been questioned. However, in a multivariate comparison, there was a distinct separation based upon cranial characters.
The genus name Lepus is derived from the Latin lepus, meaning hare. The specific epithet insularis comes from the Latin word insula indicating the island range. Additional names include black hare and Espiritu Santo jackrabbit (Thomas and Best, 1994).
Perception Channels: tactile ; chemical
The only predatory mammal on Espiritu Santo Island is Bassariscus astutus, which probably never hunts even young black jackrabbits. A few American kestrels and caracaras are the only birds of prey known on the island, thus the natural enemies of black jackrabbits are few. Since Espiritu Santo Island may never be inhabited by humans, black jackrabbits seem in no immediate danger and the population is stable. However, it may be wise to consider establishing another population on some nearby island (Thomas and Best, 1994).
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: near threatened
During the dry season when green vegetation is scarce, hares will gnaw on bark. As a result, orchards and plantations suffer at this time because the hares girdle young stems and cause plants to die (Bourne, 1997).
According to local fisherman, humans from nearby Pichilinque Island hunt black jackrabbits for food. Although its fur is not particularly valuable nor durable, it has been used to manufacture felt (Nowak, 1983).
Positive Impacts: food
Lepus insularis is an herbivore. Grasses are the preferred food choice of black jackrabbits, but these animals have also been known to consume tree bark when other food supplies are not readily available. Since Espiritu Santo Island is a virtually waterless island, all of the required water is obtained through ingested vegetation (Nowak, 1983).
Plant Foods: leaves; wood, bark, or stems
Primary Diet: herbivore (Folivore )
Lepus insularis is endemic to Espiritu Santo Island in the Gulf of California, Mexico, from sea level to 300 meters elevation. It has also been introduced to nearby Pichilinque Island (Thomas and Best, 1994).
Biogeographic Regions: nearctic (Native )
Other Geographic Terms: island endemic
This species, also known as black jackrabbits, is found all over Espiritu Santo Island but is most abundant in the valleys and adjoining lower slopes of the hills. Espiritu Santo Island is a waterless volcanic island characterized by rocky hills and low mountains. Black jackrabbits favor places scattered with arid tropical shrubs, cacti, and other plants since the upper slopes are rocky and barren (Thomas and Best, 1994).
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; chaparral
Black jackrabbits have a characteristic glossy black head, usually with a few white hairs on the middle of the crown and grayish hairs near the ears and eyes. The rest of the upper pelage, including the top of the tail, is glossy black with fine grizzling of dark cinnamon. The cinnamon color predominates ventrally. A black line extends along the inner sides of the hind feet from the toes to slightly above the heel. The soles of the feet are heavily padded. Average body size is 574 mm and average tail length is 96 mm. Like other hares, females are usually larger than males (Dixon et al., 1983).
Average length: 574 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Little is known about the reproductive patterns of black jackrabbits. Mating season is usually restricted to the milder seasons of the year. It typically lasts from January to August. Two or three litters are produced by each female during the spring and summer. Litter size is normally three to four. Gestation usually lasts 41 to 43 days. In contrast to rabbits, young black jack "rabbits" are precocial. They are well furred at birth, their eyes are open, and they can move about soon after birth. Weaning lasts only a few days, at which time the mother abandons the young (Nowak, 1983).
Breeding interval: These animals can breed up to three times per year.
Breeding season: Breeding occurs from January to August.
Average number of offspring: 3-4.
Range gestation period: 0.03 to 0.03 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Parental Investment: precocial
The black jackrabbit (Lepus insularis) is a species of mammal in the family Leporidae. Endemic to Mexico, its only known location is Espiritu Santo Island in the Gulf of California. The IUCN has listed this species as a "vulnerable species" because of its restricted range. This taxon is regarded by some authorities as being a subspecies of the black-tailed jackrabbit (L. californicus), found on the mainland of Mexico.[2]
The black jackrabbit grows to a length around 55 cm (22 in) including a tail of 9.5 cm (4 in). The top of the head, upper surface of the body, and upper side of the tail are glossy black sheened with brown. The sides of the head, body, and limbs are dark cinnamon or buffy-brown and the underparts and underside of the tail are usually some lighter shade of brown. The eyes are surrounded by a ring of grey and the insides of the ears are greyish-black and fringed with long, grey hairs.[3]
The black jackrabbit is endemic to the Island of Espiritu Santo just off the coast of Baja California in Mexico.[4] It is found on grassy and rocky slopes, plateaus, dunes, and valley bottoms, typically on bare slopes and among grasses, herbs, shrubs, and cacti.[4]
The black jackrabbit is very conspicuous as its black colouring stands out against the browns, greys, and greens of its surroundings. It is closely related to the black-tailed jackrabbit on the Mexican mainland, but the latter species is exposed to terrestrial predators and does not display melanism. On the island, large predators are absent. The black jackrabbit shares its habitat with the Espíritu Santo antelope squirrel (Ammospermophilus insularis), the spiny pocket mouse (Chaetodipus spinatus), the cactus mouse (Peromyscus eremicus), the desert woodrat (Neotoma lepida), and the ring-tailed cat (Bassariscus astutus). Also present are a number of species of lizards and snakes and two predatory birds, the crested caracara (Caracara cheriway) and the American kestrel (Falco sparverius).[3]
Since the black jackrabbit is only found on the island of Espiritu Santo, its total range covers only 95 km2 (37 sq mi), the area of the island.[4] However, it is common over much of the island and the population appears to be stable. The chief threats it faces are from the introduction of non-native species and the disturbance of its habitat by humans, and the IUCN has rated its conservation status as being "near threatened".[4] The island is uninhabited and is protected by the government of Mexico as part of the Área de Protección de Flora y Fauna: Islas del Golfo de California.[5] It is a favoured ecotourism destination and in 1995 was declared to be part of a Biosphere Reserve, Islas del Golfo de California, by UNESCO.[6]
The black jackrabbit (Lepus insularis) is a species of mammal in the family Leporidae. Endemic to Mexico, its only known location is Espiritu Santo Island in the Gulf of California. The IUCN has listed this species as a "vulnerable species" because of its restricted range. This taxon is regarded by some authorities as being a subspecies of the black-tailed jackrabbit (L. californicus), found on the mainland of Mexico.
