Black-tailed jackrabbit

The black-tailed jackrabbit (Lepus californicus), also known as the American desert hare, is a common hare of the western United States and Mexico, where it is found at elevations from sea level up to 10,000 ft (3,000 m). Reaching a length around 2 ft (61 cm), and a weight from 3 to 6 lb (1.4 to 2.7 kg), the black-tailed jackrabbit is one of the largest North American hares. Black-tailed jackrabbits occupy mixed shrub-grassland terrains. Their breeding depends on the location; it typically peaks in spring, but may continue all year round in warm climates. Young are born fully furred with eyes open; they are well camouflaged and are mobile within minutes of birth, thus females do not protect or even stay with the young except during nursing. The average litter size is around four, but may be as low as two and as high as seven in warm regions.

The black-tailed jackrabbit does not migrate or hibernate during winter and uses the same habitat of 0.4–1.2 sq mi (1.0–3.1 km²) year-round. Its diet is composed of various shrubs, small trees, grasses, and forbs. Shrubs generally comprise the bulk of fall and winter diets, while grasses and forbs are used in spring and early summer, but the pattern and plant species vary with climate. The black-tailed jackrabbit is an important prey species for raptors and carnivorous mammals, such as eagles, hawks, owls, coyotes, foxes, and wild cats. The hares host many ectoparasites including fleas, ticks, lice, and mites; for this reason, hunters often avoid collecting them.

Like other jackrabbits, the black-tailed jackrabbit has distinctive long ears, and the long powerful rear legs characteristic of hares. Reaching a length about 2 ft (61 cm), and a weight from 3 to 6 lb (1.4 to 2.7 kg), the black-tailed jackrabbit is the third-largest North American jackrabbit, after the antelope jackrabbit and the white-tailed jackrabbit. Additionally, the much more northerly Arctic hare and Alaskan hare are somewhat larger than the jackrabbit members of the hare genus. The black-tailed jackrabbit's dorsal fur is agouti (dark buff peppered with black), and its undersides and the insides of its legs are creamy white. The ears are black-tipped on the outer surfaces, and unpigmented inside. The ventral surface of the tail is grey to white, and the black dorsal surface of the tail continues up the spine for a few inches to form a short, black stripe. The females are larger than males, with no other significant differences.

Although 17 subspecies are recognized, this number may be excessive. Using cluster analysis of anatomical characters, Dixon and others found that black-tailed jackrabbit subspecies separated into two distinct groups that are geographically separated west and east of the Colorado Rocky Mountains and the Colorado River. They suggested only two infrataxa are warranted: the western subspecies L. c. californicus and the eastern subspecies L. c. texianus.

The black-tailed jackrabbit is the most widely distributed jackrabbit (Lepus species) in North America. Native black-tailed jackrabbit populations occur from central Washington east to Missouri and south to Baja California Sur and Zacatecas. Black-tailed jackrabbit distribution is currently expanding eastward in the Great Plains at the expense of white-tailed jackrabbit. The black-tailed jackrabbit has been successfully introduced in southern Florida and along the coastline in Maryland, New Jersey, and Virginia.

Six subspecies of L. californicus are in the Baja California Peninsula, three of which are endemic to the surrounding islands. The current distribution is a result of sea-level rise about 21,000 years ago, after the last glacial maximum. Due to this geographic isolation, the current subspecies of L. californicus living on the peninsula can be separated into three subclades based on similar DNA structure and pelage color. The first clade is associated with subspecies L. c. xanti, and contains all subspecies found in the southernmost part of the Baja Peninsula; it has a yellowish color pattern. The second clade is associated with subspecies L. c. magdalenae, and includes all subspecies found between the La Paz isthmus and the southern Vixcaino Desert, including subspecies L. c. xanti, L. c. sheldoni, and L. c. martirensis. This clade has a coloration pattern range of light brown to yellow. The third clade is associated with subspecies L. c. martirensis, and includes all subspecies found from the Viscaino Desert to the northernmost part of the peninsula.

Distribution of subspecies occurring entirely or partially in the United States is:

The black-tailed jackrabbit occupies plant communities with a mixture of shrubs, grasses, and forbs. Shrubland-herb mosaics are preferred over pure stands of shrubs or herbs. Black-tailed jackrabbit populations are common in sagebrush (Artemisia spp.), creosotebush (Larrea tridentata), and other desert shrublands; palouse, shortgrass, and mixed-grass prairies; desert grassland; open-canopy chaparral; oak (Quercus spp.), and pinyon-juniper (Pinus-Juniperus spp.) woodlands; and early seral (succeeding each other), low- to mid-elevation coniferous forests. It is also common in and near croplands, especially alfalfa (Medicago sativa) fields.