Antelope Jackrabbit, Lepus alleni
Antelope Jackrabbit, Lepus alleni. Photograph taken with the confines of the Arizona-Sonora Desert Museum, Tucson, Arizona, February, 2022.
The Antelope Jackrabbit, Lepus alleni, is a member of the Leporidae family of rabbits and hares. The Leporidae family has seventy species placed in thirteen genera. There are thirty species are in the genus Lepus. They are one of five jackrabbit species that inhabit North America. The Antelope Jackrabbit is known in Mexico as Liebre Antílope.
The Antelope Jackrabbit is named after the fast, leaping antelopes found in the plains of Africa. Their powerful legs allow the Antelope Jackrabbit to run at speeds of 72 km per hour (44 mph) and similar to the antelope, the jackrabbit displays flashes of their white underside as they run. They typically grow to be 50 cm (18 inches) to 60 cm (2 feet 0 inches) in length with their front legs growing 10 cm (3.9 inches) to 20 cm (7.9 inches) long and their hind legs growing 20 cm (7.9 cm) to 30 cm (11.8 inches) in length. They weigh between 2.7 kg (5.95 pounds to 4.73 kg (5 pounds 15 ounces) to 10.42 kg (22 pounds 15 ounces). When fully grown, the Antelope Jackrabbit’s ears grow to be 5.1 cm (2.0 inches) to 20.3 cm (8.0 inches) in length. Their ears are used not only to hear, but also to reduce and regulate their body heat for survival in the hot environment they live in. The sides of their body (limbs, hips, rump) have white hair with black tips while the ventral surface (chin, throat, stomach, insides of limbs) and tail have white hair. The rest of their body is yellow/brown with some black. Their fur is highly reflective and insulated which helps to reduce heat gain from the environment.
Like other jackrabbits, Antelope Jackrabbits are solitary. They are nocturnal and crepuscular (active during dawn and dusk) but may be active during the day when it is cloudy. They primarily spend their days in the hot season staying out of the sun in “shelter forms”. These are created by backing up under grass, weeds, or brush, or just by sitting in the shade of a cactus. Antelope Jackrabbits are herbivores, primarily consuming foliage, grass, and cacti. They do not actively drink water, but derive it from their diet, especially from consuming cacti stems. In the drier months, May and June, they primarily depend on mesquite leaves and cacti while during rainy season, July and August, they primarily consume grass. They are also coprophagic and consume their pellets.
Mating behavior is not well-known as only two copulations have been observed. However, both copulations were characterized by an aggressive female. Male Antelope Jackrabbits will fight by boxing. Standing on their hind feet, they use their forelimbs to strike each other quickly and repeatedly for several seconds. The exchange is usually quiet and ends when the winner chases the loser away. Fights can be aggressive enough to cause torn ears, cuts, and rarely severe injuries such as a lost paw. Male on male fighting is believed to be related to competition for females, however their mating system is not well-known. Breeding occurs from late December through September. The female gestation period is about six weeks with litter sizes ranging from one to five young. Females are iteroparous and have three or four litters each year when conditions are favorable. Like most hares, Antelope Jackrabbit young are precocial and are weaned just a few days after birth. At five days old, the young jackrabbits have well-developed incisors and are covered in short fur. Parental care is provided by the female who returns at night to nurse her young. However, the length of parental care is short and young become independent in a matter of days. The exact lifespan of the Antelope Jackrabbit is unknown, as they are difficult to keep in captivity, but on average they live between two and five years in the wild.
The Antelope Jackrabbit may commonly be confused with other species of hare including the Black-tailed Jackrabbit, Lepus californicus. The Antelope Jackrabbit can be identified by their large ears while the Black-tailed Jackrabbit can be distinguished by a black tail and ear-tips. From a conservation perspective, the Antelope Jackrabbit is currently considered to be of Least Concern. Current threats include increased predation, habitat fragmentation, animal competition (livestock), and exotic grasses. They are also hunted for sport and local subsistence. The greatest impact on the population of Antelope Jackrabbits found on Tiburon Island is the presence of predators such as coyotes and gray foxes.