The common name antelope jackrabbit is derived from the white flashing behavior of American pronghorns (Antilocapra americana) when they run. Antelope jackrabbits also flash their white tails when they flee.
Lepus alleni is named after John Asaph Allen who was the Curator of the Department of Mammals and Birds at the American Museum of Natural History.
Common names include: Allen's hare, Allen's jackrabbit, blanket jack, burro jack, jackass rabbit, Mexican jackrabbit, saddle jack, and wandering jackrabbit.
Antelope jackrabbits uses their long ears to listen for predators and get a sense of their surroundings. Only in rare circumstances do antelope jackrabbits use sound as a form of communication. A pheromone may be used by this species in the form of a rectal gland that secretes a strong musky odor and may be used to scent mark a shelter form.
Communication Channels: visual ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Lepus alleni habitat in southern Arizona is threatened by Lehmann lovegrass (Eragrostis lehmanniana), a non-native grass species which is not edible for antelope jackrabbits. Conversion of wild land for agriculture will lead to a further decline in antelope jackrabbit populations. Human impacts on antelope jackrabbit habitat also include housing developments, livestock grazing, recreational trails, and canal building.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Through grazing, Lepus alleni is sometimes said to compete with domestic animals that graze on the same land. However, the impact may not be substantial as rabbits may graze in different ways and on different plants than domestic animals. In terms of quantity 15 antelope jackrabbits consume as much as 1 sheep, and 74 antelope jackrabbits consume as much as 1 domestic cow.
Antelope jackrabbits are valuable for food and their skin.
Positive Impacts: food ; body parts are source of valuable material
Through their grazing, antelope jackrabbits can force habitat succession in the direction of the climax stage on a range that is moderately deteriorated. On range that has more weeds than grasses (indicating worse deterioration), their grazing may further degrade the habitat. Antelope jackrabbits are important prey for medium to large terrestrial and avian predators. Their folivory influences the composition and health of their native habitats.
Mutualist Species:
Commensal/Parasitic Species:
Lepus alleni is a folivore (leaf-eater), gramnivore (grass-eater) and succulent plant eater (esp. cacti). They do not actively drink water, but derive it from their diet, especially from eating cacti stems. May and June are the most arid months in their range and the rainy season occurs in July and August. In the dry season they depend mostly on mesquite leaves and cacti, but during the wet season, they switch to grass. Some minerals are derived from geophagy, but this behavior is rare.
Plant Foods: leaves; wood, bark, or stems
Primary Diet: herbivore (Folivore )
Lepus alleni, the antelope jackrabbit, is found mostly along the western coast of Mexico, but also in southern Arizona in the United States. In Mexico, antelope jackrabbits inhabit the Mexican states adjacent to the Gulf of California and the Pacific Ocean: Sonora, Sinaloa, and northern Nayarit. In Arizona, antelope jackrabbits inhabit a small southern area, mostly in the Sonoran desert. Lepus alleni is also located on Tiburon, a small island off the coast of the Mexican state of Sonora.
Biogeographic Regions: nearctic (Native )
In Arizona, antelope jackrabbits inhabit grassy slopes at moderate elevations. They are most commonly found in areas where grass grows well under desert shrubs that are moderately high and open. They are less common in creosote bush desert and in the low parts of valleys with dense mesquite stands. In Mexico, antelope jackrabbits prefers grasslands that are open and low, as well as foothills with patchy, low bushes and grass. They are most common in the foothills near the coast.
Range elevation: 0 to 1,500 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral
Other Habitat Features: agricultural
Not much is known about the lifespan of antelope jackrabbits as they are hard to keep alive in captivity and they are difficult to capture and study in the wild.
Size is the most distinctive trait of Lepus alleni; it is a large Lepus species, with the head and ears being especially large. Their ears are tall (on average 162mm long) and mostly devoid of hair except for fringes of white hair along the edges and on the tips. The side of the body (limbs, hips, rump) are white haired with black tips. The ventral surface (chin, throat, stomach, insides of limbs) are all white haired as well as the tail. The rest of the body (upper part) is yellow/brown with some black.
Lepus alleni deals with seasonality by adjusting its basal metabolic rate. It increases by 15% during the winter compared to the summer.
Antelope jackrabbits have many ways of dealing with heat. The fur is highly reflective and insulated, which helps to eliminate heat gain from the environment. Antelope jackrabbits can reduce blood flow to their large ears, which reduces heat exchanger. When not able to find shelter, Lepus alleni can tolerate heat stress at high levels better and for a longer time than Lepus californicus.
Range mass: 2.7 to 4.73 kg.
Average mass: 3.8 kg.
Range length: 553 to 670 mm.
Average length: 622 mm.
Range basal metabolic rate: 8.34 to 10.06 cm3.O2/g/hr.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: sexes alike
Lepus alleni is precocial at birth and ready to flee if a predator finds the mother and young soon after birth. Young are more nocturnal, less likely to leave a shelter, and generally more wary of their surroundings than are adults. Once grown, there are many predator avoidance strategies. One is to sit in a shelter form that is open on three sides, but offers protection from birds of prey. If a terrestrial predator is detected, the antelope jackrabbit can run or conceal itself in a shelter form. If it stays concealed, it will back into the shelter form, lay its ears close to the body, and extend the forelimbs for a quick escape. If it decides to run, it will take to all fours and flash a white area on its rump towards the predator. As it runs away in a zig-zag pattern, it will keep a white area exposed towards the predator, in hopes of confusing it. The antelope jackrabbit will also hop like a kangaroo in tall grasses to be able to see where the predator is.
Known Predators:
Anti-predator Adaptations: cryptic
Only 2 copulations have been observed, so mating behavior is not well known for Lepus alleni. Both copulations were characterized by an aggressive female: one was aggressive afterwards, growling and chasing the male away and the other female growled and fought with the male before mating.
Antelope jackrabbit males will fight by boxing. They stand on their hind feet, using their forelimbs to strike each other repeatedly and rapidly for several seconds. This exchange is usually quiet and the fight ends when the winner chases the loser away. Fights can be serious enough to wound a jackrabbit badly, including torn ears, cuts, and even rare injuries such as one case where a male lost the paw of its forelimb. Male on male fighting is likely to be related to competition for females, but the mating system is not well known.
Mating System: polygynandrous (promiscuous)
The gestation period for a female is about 6 weeks, with an average of 2 young per litter. Litter sizes range from 1 to 5 young. Females can have 3 or 4 litters each year. Like most hares (Lepus), antelope jackrabbit young are born well-developed and are weaned and independent just a few days after birth, exact numbers are not given in the literature. By 5 days old the young have well-developed incisors and are covered in short fur. Young are not born with the characteristic white rump, but the rump flash can be displayed at as young as 19 days if the young antelope jackrabbit is alarmed.
Breeding interval: Females have 3 to 4 litters each year when conditions are good.
Breeding season: Breeding occurs from late December through September.
Range number of offspring: 1 to 5.
Average number of offspring: 2.
Average gestation period: 6 weeks.
Average age at sexual or reproductive maturity (female): 2 years.
Average age at sexual or reproductive maturity (male): 2 years.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
It is thought that female antelope jackrabbits scatter their young in different hiding places after birth, and return to feed the young at night. There are no indications of burrows made by mothers for their young, but there are a few instances of well concealed "nests." One nest was concealed under some beargrass, another under a mesquite near sacaton grass and one was even in a hollowed-out barrel cactus shell. Females invest heavily in the development of their young during gestation, giving birth to precocial young that are independent just a few days after their birth. Male antelope jackrabbits do not contribute to the care of their young.
Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)
