The black-tailed jackrabbit (Lepus californicus), or desert hare, is the common hare of the western United States and Mexico. It is found at elevations from sea level to up to 9,843 feet (3000 m).
The black-tailed jackrabbit has unmistakable long ears, and the long powerful rear legs characteristic of hares. Its fur is dark buff peppered with black. Its ears are tipped with black, and it has a black stripe down its back. The tail is black above but white beneath. It is the third largest North American hare behind the Antelope jackrabbit and the white-tailed jackrabbit. It reaches a length of about 23.63 in (60 cm), and adults weigh between 3.31 and 8.81(1.5 and 4 kg).
The black-tailed jackrabbit is commonly seen on pasture and wasteland during the day. It is predominantly nocturnal in its habits. It feeds on cactus, sagebrush, mesquite, grasses, and crop plants such as clover and alfalfa. They drink little, deriving water from their food. Black-tailed jackrabbits do not use burrows, but rest during the day in a scrape in the pasture called a form. They rely on their acute hearing and speed to evade predators. They can reach speeds of up to 34 miles per hour (55 km/h), and can leap (6 m) in a single bound. Their predators include birds of prey and mammalian carnivores as coyotes, foxes, bobcats and weasels. They are largely solitary animals. The white underside of the tail of a fleeing jackrabbit probably serves as a warning signal to other members of the species. Jackrabbits will also thump the ground with their hind legs as an alarm signal.
Breeding can occur year-round in the south of the species’ range. Up to four litters may be produced in a year, with up to eight young in a litter. They are born in a form, above ground. Gestation is long (around 45 days) and the young are mature
Black-tailed Jackrabbit populations are characterized by extreme “boom-bust” cycles. These cycles can be very localized. Jackrabbits may be plentiful in one valley and almost absent from an adjacent valley. Population crashes are mostly due to disease (especially Tularemia), although environmental factors such as food availability can also play a part. The high birthrate of the Jackrabbit allows populations to recover quickly after a crash. These cycles also have a large effect on predator populations.